OBD-II Code C1597: Manufacturer-Specific Fault Guide

What Does C1597 Mean?

C1597 is a manufacturer-specific code with three completely different meanings. For General Motors (GM) trucks and SUVs, it signals a critical power loss to the electric power steering system, causing a complete loss of steering assist. For Dodge, Ram, Chrysler, and Jeep vehicles, it indicates the Tire Pressure Monitoring System (TPMS) entered 'Winter Mode' because it cannot detect any tire sensors. A rare definition exists for some Toyota/Lexus models relating to a communication failure within the Variable Gear Ratio Steering (VGRS) system.

Technical definition: The Society of Automotive Engineers (SAE) lists C-codes as chassis-related, but C1597 lacks a universal definition. Manufacturer-specific definitions include: General Motors: "Power Steering Control Module Malfunction Level 1." Dodge/Ram/Chrysler/Jeep: "TPM System Deactivated-Winter Mode." Toyota/Lexus: "Lost Communication Between VGRS And EPS" or "Communication problem with the DRS ECU."

Can I Drive With C1597?

No — Do Not Drive. For GM vehicles, absolutely not. Sudden loss of power steering makes driving extremely dangerous and difficult to control. For Dodge/Ram/Jeep vehicles, the vehicle is mechanically safe to drive, but you lose low tire pressure warnings, increasing the risk of a blowout.

Common Causes

• Poor or Corroded Main Ground Straps (GM) (Very Common) — On affected GM trucks, the most frequent cause is a bad connection at the main engine or frame ground straps (G132, G133). Corrosion or looseness interrupts the sensitive voltage supply to the electric power steering module, causing it to shut down. This is documented in GM TSB PIT6088.
• Sensorless Winter/Aftermarket Wheels (Dodge/Ram/Jeep) (Very Common) — This is the intended function of the code on these vehicles. When you swap to wheels that lack TPMS sensors (common for winter tires), the system deactivates after failing to find any sensors and logs this informational code.
• Dead TPMS Sensor Batteries (Dodge/Ram/Jeep) (Common) — TPMS sensor batteries have a finite life, typically 5-10 years. If all four fail around the same time, the system behaves as if there are no sensors present, triggering the 'Winter Mode' code.
• Damaged PSCM Wiring Harness (GM) (Common) — The wiring harness leading to the Power Steering Control Module (PSCM) chafes, corrodes, or sustains damage from road debris. This causes an intermittent loss of power and communication that triggers the C1597 code, even if the grounds are good.
• Faulty Radio Frequency Hub (RFH) (Dodge/Ram/Jeep) (Less Common) — The RFH module receives signals from the TPMS sensors. If this module fails, it cannot detect any sensors and incorrectly puts the system into 'Winter Mode', setting the C1597 code even with good sensors installed.
• Faulty Power Steering Control Module (GM) (Rare) — While less common than a ground or wiring issue, the power steering control module itself fails internally due to software glitches or hardware failure. Consider this only after exhaustively ruling out all power and ground issues.
• Local CAN Communication Failure (Toyota/Lexus) (Rare) — On vehicles with VGRS, this code indicates the steering control ECU lost communication with the power steering ECU. This indicates a wiring issue in the local CAN bus, a faulty VGRS ECU, or a faulty power steering ECU.

Symptoms

• Complete Loss of Power Steering (GM) — The steering becomes very heavy and difficult to turn, especially at low speeds. A 'Service Power Steering' message appears on the dash.
• TPMS Light Off, Dashes on Display (Dodge/Ram/Jeep) — After an initial warning, the TPMS light turns off on subsequent startups. The digital display in the instrument cluster shows dashes (--) instead of numbers, indicating the system is in 'Winter Mode'.
• Initial TPMS Light Flashes, Then Stays On (Dodge/Ram/Jeep) — When wheels with no sensors are first installed, the TPMS warning light flashes for about 60-90 seconds and then stays on. A 'SERVICE TPM SYSTEM' message appears before the system fully enters Winter Mode.
• Flickering Lights or Other Electrical Issues (GM) — Because the root cause is often a bad main ground, you notice dimming or flickering headlights, erratic gauges, or other strange electrical behavior pointing to a systemic voltage problem.
• VGRS Warning Light On (Toyota/Lexus) — The instrument cluster displays a warning light specific to the Variable Gear Ratio Steering system, indicating a malfunction.
• PSCM Voltage PID Low (GM) (scan-tool only — no driver-felt sign) — When viewed with a scan tool, the live data for the Power Steering Control Module shows a voltage reading below the minimum threshold (e.g., <9.0V), confirming the module is not receiving adequate power.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this code.

Common Fixes & Costs

• Clean and Repair Main Ground Straps (GM) — Parts: $10-$50, Labor: $150-$250, ~1.5 hr book time (Intermediate)
• Reinstall Original Wheels with TPMS Sensors (Dodge/Ram/Jeep) — Parts: $0, Labor: $40-$120, ~0.8 hr book time (DIY)
• Install Four New TPMS Sensors (Dodge/Ram/Jeep) — Parts: $120-$250, Labor: $100-$225, ~1.8 hr book time (Professional)
• Replace Power Steering Control Module (GM) — Parts: $400-$900, Labor: $200-$400, ~3.5 hr book time (Professional)
• Replace Radio Frequency Hub (RFH) Module (Dodge/Ram/Jeep) — Parts: $350-$450, Labor: $75-$150, ~1.2 hr book time (Professional)

Used vs. New Parts: Buying Guide

When a used part is worth it: For expensive electronic modules like a Power Steering Control Module (PSCM), a used part from a low-mileage, accident-damaged vehicle is a cost-effective option, BUT ONLY if you confirm it does not require VIN programming or have access to tools that can do it.

Donor-vehicle mileage cap: roughly under 60000 miles for the part to have meaningful remaining life.

Donor quality checklist:

• Verify the exact part number matches; superseded numbers are often incompatible.
• Avoid parts from flood-damaged or high-corrosion (rust belt) vehicles.
• For a Radio Frequency Hub (RFH), a used part is NEVER a viable option as they are security components permanently programmed to the original vehicle's VIN.

Decision logic:

• If The part is a security component like an RF Hub or Immobilizer → Buy new from the dealer or a specialist that pre-programs to your VIN. A used part will not work.
• If The part is a GM PSCM and requires programming to the vehicle → Buy new, unless you have a confirmed professional who programs used modules. The labor cost of a failed used part install outweighs the savings.
• If The part is a simple ground strap → Always buy new. The cost is minimal ($10-$50) and a used part carries the same risk of corrosion.

Warranty tradeoff: Used parts typically have a 30-90 day warranty at best. New aftermarket parts offer 1-year to limited lifetime warranties. New OEM parts carry a 1-2 year warranty.

Worst-case if a used part fails: $500-$1000 if a used electronic module fails after installation, requiring repeat labor costs for removal, re-installation, and programming of a new part.

What Happens If You Wait — Timeline

1. Stage 1: Intermittent Failure (First Occurrence to 1 Month): The 'Service Power Steering' light appears, and steering assist is lost, often during a low-speed turn. The issue resolves itself after a key cycle. This is caused by a borderline ground connection with high resistance. (MPG impact: 0%% · Added cost: $0)
2. Stage 2: Frequent Failure (1-3 Months): Power steering failures become frequent and unpredictable, creating a significant safety hazard. The ground strap is severely corroded and close to breaking. (MPG impact: 0%% · Added cost: $0 - $1500+ (Cost of an accident due to unexpected loss of steering control).)
3. Stage 3: Permanent Failure (3+ Months): The ground strap breaks completely. Power steering assist is permanently lost. The vehicle is extremely difficult and unsafe to drive. Continued driving without assist puts severe strain on mechanical steering components. (MPG impact: 0%% · Added cost: $1200-$2500 (Premature wear on the steering rack requiring replacement).)
4. Stage 1: TPMS Disabled (Immediate): After installing wheels without sensors and driving for 10-20 minutes, the C1597 code sets and the TPMS system is disabled. There is no warning for low tire pressure. (MPG impact: 0%% · Added cost: $0)
5. Stage 2: Undetected Slow Leak (1-6 Months): A tire develops a slow leak, but the driver is not alerted. Driving on the underinflated tire reduces fuel economy by up to 3-5% and causes accelerated, uneven tread wear. (MPG impact: 3-5%% · Added cost: $50 (wasted fuel) to $300 (premature replacement of one tire).)
6. Stage 3: Catastrophic Failure (6+ Months): Continuously driving on a severely underinflated tire leads to overheating of the tire's sidewall and a catastrophic blowout at highway speeds. This causes a complete loss of vehicle control. (MPG impact: 5-10%% · Added cost: $250 (new tire) to $5,000+ (Cost of accident repairs, including potential damage to the wheel, fender, and suspension components).)

Cost of Not Fixing It

• Immediate (GM): Sudden loss of power steering assist creates a major safety hazard, making the vehicle extremely difficult to control, especially at low speeds or in emergencies. This causes accidents. (Added cost: $0 to Total Loss of Vehicle)
• Immediate (Dodge/Ram/Jeep): The TPMS system is disabled, providing no warning for a low tire. An undetected slow leak leads to a catastrophic tire failure (blowout) at highway speeds, causing loss of control. (Added cost: $250 (new tire) to $10,000+ (accident repairs))
• 1-6 Months (GM): Continuously operating with an intermittent power steering failure places severe stress on the steering rack and motor. Driving the vehicle without assist strains steering components not designed for manual effort. (Added cost: $1200-$2500 (potential steering rack replacement))
• 1-6 Months (Dodge/Ram/Jeep): Driving on underinflated tires causes accelerated and uneven tire wear, and reduces fuel economy by up to 3%. This requires premature tire replacement. (Added cost: $250-$1200 (premature tire replacement))

Diagnosis Steps

1. Identify Your Vehicle Manufacturer
   The first and most important step is to know if you are driving a GM vehicle (like a Silverado/Sierra), a Stellantis vehicle (Dodge/Ram/Chrysler/Jeep), or a Toyota/Lexus. The diagnosis for C1597 is completely different for each.
   Tools: None (Beginner)
2. GM Diagnosis: Inspect and Voltage Drop Test Main Grounds
   Visually inspect main ground connections G132 and G133 (behind the front passenger-side wheel well liner) for corrosion or breakage. Then, with the vehicle running, set a multimeter to DC Volts. Place the positive lead on the negative battery terminal and the negative lead on the Power Steering Control Module (PSCM) casing. A reading above 100mV (0.1V) confirms a bad ground connection that needs repair, even if it looks clean.
   Tools: Flashlight, Multimeter (Intermediate)
3. Dodge/Ram/Jeep Diagnosis: Verify Wheel and Sensor Setup
   Determine if you recently swapped your wheels or tires. If you installed winter tires or aftermarket wheels, they likely lack TPMS sensors, which is the expected reason for this code. No repair is needed unless you want TPMS functionality.
   Tools: None (Beginner)
4. GM Diagnosis: Clean and Tighten Grounds
   If a ground fails the visual or voltage drop test, disconnect the negative battery terminal. Remove the ground bolt, clean the contact surfaces of the strap, eyelet, and frame/engine block to bare metal using a wire brush. Re-secure the connection tightly and apply dielectric grease to prevent future corrosion.
   Tools: Socket set, Wire brush, Dielectric grease, Safety glasses (Intermediate)
5. Dodge/Ram/Jeep Diagnosis: Scan TPMS Sensors
   If you have not changed your wheels, all four sensors likely failed. A tire shop or dealership uses a TPMS diagnostic tool to scan each wheel and verify if the sensors transmit a signal. If none respond, they failed due to dead batteries or incompatibility.
   Tools: TPMS Diagnostic Tool (Professional)
6. GM Diagnosis: Check PSCM Live Data
   If cleaning grounds fails, use an advanced scan tool to access the Power Steering Control Module live data. Monitor the 'PSCM Voltage' PID. With the engine running, this must match battery voltage (13.5V - 14.8V). A reading below 9.0V causes the module to shut down. Check the wiring harness for continuity before condemning the module.
   Tools: Advanced Scan Tool, Multimeter (Advanced)
7. Toyota/Lexus Diagnosis: Check CAN Bus Resistance
   For the VGRS fault, test the local CAN bus. Turn the ignition off and disconnect the VGRS ECU connector. Measure the resistance between the CAN High and CAN Low terminals. A healthy CAN bus reads between 100 and 140 ohms. A reading outside this range indicates a wiring problem or a failed terminating resistor.
   Tools: Multimeter, Vehicle-specific wiring diagram (Professional)

When This Code Triggers (Freeze-Frame Conditions)

• PSCM Voltage (GM): < 9.0 Volts (The code triggers the moment the Power Steering Control Module voltage drops below the operational threshold, often during high electrical load or when a poor ground connection is disturbed.)
• Vehicle Speed: > 15 mph (For Dodge/Ram/Jeep, the system must see the vehicle driving at a speed greater than 15 mph for a cumulative period (10-20 minutes) to confirm no TPMS sensors are responding before setting the C1597 'Winter Mode' code.)
• Engine State: Running (The vehicle's engine must be running for the fault to be detected. For GM, the power steering system is active; for Dodge/Ram, the RFH module is actively searching for sensor signals.)
• Time Since Start: 10-20 minutes (For the Dodge/Ram TPMS issue, the code does not set immediately. It requires drive time to verify all four sensors are truly absent.)

Related Codes

• C1599 — On GM vehicles, C1599 is often set along with C1597. Both point to a fault in the power steering control module circuit. If you have both codes, check power and grounds to the PSCM first.
• P25A2 — This is a powertrain code for 'Brake System Control Module Requested MIL Illumination'. It sets in the ECM when the power steering module goes offline due to the same ground issue that sets C1597. Seeing P25A2 alongside C1597 strongly points towards the known GM ground strap problem.
• U0420 — This is a network code for 'Invalid Data Received From Power Steering Control Module'. It sets in other modules when they can no longer communicate with the PSCM. If you have U0420 along with C1597, it confirms the PSCM is offline.
• C0569 — On GM vehicles, this code for 'System Configuration Malfunction' sometimes appears with TPMS-related issues. For Dodge/Ram/Jeep, if C1597 is present because of incompatible sensors, you may also see codes indicating a sensor is not programmed correctly.

Climate & Environmental Factors

• Cold Weather: For GM vehicles, cold temperatures exacerbate poor electrical connections, making the ground issue more prominent. For Dodge/Ram/Jeep vehicles, cold weather reduces the battery voltage in aging TPMS sensors, causing them to stop transmitting.
• High Humidity / Road Salt: This is a major contributing factor for the GM C1597 issue. States in the 'Salt Belt' see significantly higher rates of corrosion on frame grounds and electrical connections, making this failure much more common.
• High Temperatures: Extreme heat accelerates the chemical degradation of TPMS sensor batteries, shortening their overall lifespan from the typical 5-10 years. This leads to premature failure of all four sensors.

How to Talk to a Mechanic About This Code

Say this: "For a GM vehicle: 'I have a C1597 code and a 'Service Power Steering' message. Based on TSB PIT6088, I'd like to schedule a diagnosis focusing on a voltage drop test of the power steering module's ground circuit before any parts are replaced.' For a Dodge/Ram: 'I have a C1597 code after installing wheels without TPMS sensors. I believe it's in 'Winter Mode.' Can you confirm this is informational and not a system fault?'"

For GM, this immediately directs the technician to the most likely, and cheapest, cause, preventing a premature quote for a $2,500 steering rack. For Dodge/Ram, it shows you've done your research and prevents you from being charged a diagnostic fee for normal vehicle behavior.

Avoid saying:

• 'My steering feels heavy, just fix it.'
• 'My tire light is on, can you check it out?'
• 'The internet said it's a ground wire.' (Let them perform the test you requested)

Questions to ask before authorizing the repair:

• For GM: 'What was the exact voltage drop reading on the PSCM ground? Is it over 100 millivolts?'
• For GM: 'If the ground is bad, does the quote include cleaning the contact points to bare metal and applying a corrosion inhibitor?'
• For Dodge/Ram (if getting new sensors): 'Does your quote include mounting, balancing, and the sensor relearn procedure?'
• What is the warranty on the parts and labor for this repair?

Where to Take It: Dealer vs Independent vs Chain

• Dealer: A good option for the GM issue if you want to be certain the TSB is followed, or if a module replacement is truly necessary. Overkill and overpriced for the Dodge/Ram TPMS issue unless the RFH module is faulty.
  Best for: Vehicles under warranty., Confirming TSBs (like GM's PIT6088)., Programming new security-related modules like a PSCM or RFH.
  Downsides: Highest labor rates, often 1.5-2x an independent shop., Quick to recommend a full module/rack replacement if initial checks are inconclusive. (Typical cost: +50% vs. baseline)
• Independent Shop: Best fit for the GM power steering fault. An experienced independent technician performs a voltage drop test and replaces a ground strap far more cheaply than a dealer. Also a good choice for the Dodge/Ram TPMS sensor replacement.
  Best for: Out-of-warranty vehicles., Diagnosing the GM ground strap issue, which is a straightforward electrical test., Cost-effective diagnosis and repair.
  Downsides: Quality and experience with modern vehicle electronics varies widely., Lacks the expensive tools to program a new module if one is needed. (Typical cost: +0% vs. baseline)
• Chain Shop: AVOID for the GM power steering diagnosis. Recommended for the Dodge/Ram issue ONLY if you need new TPMS sensors installed; tire shops are specialists at this and offer competitive pricing.
  Best for: Tire sales and installation., Simple, defined jobs like battery replacement or oil changes.
  Downsides: Technician skill varies dramatically., Ill-equipped for complex electrical diagnostics., High pressure to upsell. (Typical cost: -10% vs. baseline)

When to Walk Away From the Repair

If an estimated repair cost exceeds 40-50% of the car's Kelley Blue Book (KBB) private-party value, pause and consider alternatives like selling the vehicle as-is.

• Car worth $10000, fix is $2500: Borderline. This is a 25% repair-to-value ratio. The fix is likely worth it, but only after getting a second opinion to confirm the expensive part (e.g., steering rack) is truly the point of failure.
• Car worth $22000, fix is $250: Fix it. This is the typical cost for the GM ground strap repair. It is a tiny fraction of the vehicle's value and a clear-cut decision.
• Car worth $18000, fix is $450: Fix it. This is the typical cost to replace all four TPMS sensors on the Dodge/Ram. It is well below the threshold and restores a key safety feature.

What Scan Tool You Need for This Code

Minimum: For GM, a tool that reads live data from the Power Steering Control Module (PSCM) is required. For Dodge/Ram, a basic code reader is sufficient to see the code, but a dedicated TPMS tool is needed to test sensors.

A basic $20 code reader only shows the C1597 code. It cannot show the live PSCM voltage on a GM to confirm a power drop, nor can it test or relearn TPMS sensors on a Dodge/Ram. For this code, a multimeter is more important for the most common GM fix than a scanner.

Budget: BlueDriver Pro (~$100) — Connects to your smartphone and displays live data streams, allowing you to monitor the PSCM voltage on a GM vehicle to see if it drops out. It reads enhanced codes from other modules.

Mid-range: FOXWELL NT530/NT710 for GM (~$180) — Provides manufacturer-specific diagnostics for GM vehicles. It accesses the PSCM for deep analysis and offers bidirectional controls. Some Foxwell models have TPMS relearn functions.

Professional: Autel MaxiCOM MK808S / Launch X431 Elite 2.0 Pro (~$450-600) — Offers full bidirectional control to test modules and components directly. These tools have comprehensive TPMS functions to diagnose, program, and relearn sensors for the Dodge/Ram scenario, and provide full access to all modules on the GM.

Rent vs buy: For a one-time diagnosis, most auto parts stores do not rent scanners with the required live data or TPMS capabilities. For the GM issue, buying a quality multimeter ($30) is a better investment than a scanner. For the Dodge TPMS issue, the diagnosis and repair is best left to a tire shop with specialized tools. Buy a scanner only if you plan to perform regular DIY maintenance on modern cars.

How to Clear the Code After You Fix It

1. For GM: After cleaning/replacing grounds, reconnect the battery. The fault clears on its own after a key cycle. If not, use an OBD-II scanner to clear codes from the PSCM.
2. For Dodge/Ram: After reinstalling wheels with working TPMS sensors, simply drive the vehicle. The code clears itself automatically.
3. A hard reset can be performed by disconnecting the negative battery terminal for 15-20 minutes, though this clears other learned settings.

Drive cycle (~20 minutes): For GM, no specific drive cycle is required; the fix is electrical. For Dodge/Ram, to clear the code after reinstalling TPMS wheels, drive the vehicle for 10-20 minutes at speeds above 15 MPH. The TPMS light flashes and then goes out as the system relearns the sensor IDs.

Readiness monitors affected: This is a 'C' (Chassis) code and does not affect emissions readiness monitors like the Catalyst or O2 sensor monitors., However, disconnecting the battery resets all readiness monitors to 'Not Ready'.

Before emissions retest: drive at least 100 miles to fully set monitors.

Watch out for:

• For GM, clearing the code without fixing the bad ground is pointless; the code returns immediately.
• For Dodge/Ram, the code is informational. There is no need to clear it unless you reinstalled TPMS sensors.
• Disconnecting the battery to clear codes erases radio presets and learned transmission/engine parameters.

Will This Fail Emissions / State Inspection?

No — by itself this code doesn't fail OBD inspection (but it can keep readiness monitors from setting, which causes a separate fail).

• General: As a 'C' (Chassis) code, C1597 does not cause a failure of an emissions-only test (smog check). However, any illuminated warning light on the dashboard is grounds for failure in states with comprehensive safety inspections.
• California: This code does not fail the OBD-II emissions portion of the smog check. However, if a related powertrain code like P25A2 is also present, that causes a failure.
• New York: NYS safety inspections fail a vehicle for any illuminated malfunction indicator lamp related to safety, including the 'Service Power Steering' message (GM) or a flashing TPMS light (Dodge/Ram).
• Texas: The Texas safety inspection explicitly checks the power steering system. Low fluid or other malfunctions are cause for rejection. A GM vehicle with an active C1597 and no power assist fails.

Most Commonly Affected Vehicles

• Chevrolet Silverado 1500 (2019-2022) — Prone to power steering failure due to poor ground connections as outlined in GM TSB PIT6088. The 2019-2021 models and the 2022 LTD models are specifically mentioned.
• GMC Sierra 1500 (2019-2022) — Shares the same platform and electrical issues as the Silverado 1500, as noted in GM TSB PIT6088.
• Ram 1500 / 2500 / 3500 (2010-2024) — These trucks have the 'Winter Mode' feature that sets C1597 when wheels without TPMS sensors are used. Most models from 2011+ use a 433MHz sensor.
• Dodge Grand Caravan / Durango (2011-2024) — Models built for the Canadian or export (BUX) markets set C1597 when TPMS sensors are not detected.
• GMC Yukon / Yukon XL (2019-2022) — Shares the same chassis and electrical architecture as the Silverado/Sierra and is susceptible to the same ground strap issues causing power steering failure.
• Chevrolet Tahoe / Suburban (2019-2022) — Also built on the T1 platform, these SUVs experience the same C1597 power steering fault due to bad grounds.
• Jeep Grand Cherokee / Wrangler (2011-2024) — Like other Stellantis vehicles, enables 'Winter Mode' and sets C1597 if no TPMS sensors are detected. 2008 and newer models use 433MHz.
• Toyota / Lexus GS / LS with VGRS (2006-2017) — On models equipped with Variable Gear Ratio Steering, C1597 indicates a communication problem between steering ECUs, a completely different and rare issue.

Manufacturer-Specific Notes

• General Motors: On 2019-2022 T1 platform trucks and SUVs, C1597 almost always points to a poor ground connection causing a loss of power steering, not a faulty module itself. This is documented in TSB PIT6088.
• Dodge / Ram / Chrysler / Jeep: The C1597 code is an intentional feature called 'Winter Mode'. It is designed to deactivate the TPMS warnings when it detects no sensors are present, a common scenario for owners with a second set of winter wheels. It is not considered a fault.
• Toyota / Lexus: The C1597 code is used for a highly specific communication error between the front (VGRS) and rear (DRS) steering control modules. Diagnosis requires checking a dedicated local CAN bus, not the main vehicle CAN network.
• Stellantis (Formerly FCA): The 'Winter Mode' feature is primarily enabled on vehicles intended for the Canadian and export (BUX) markets where TPMS was not mandated as strictly as in the US. Some US models may not have this feature.

Real Owner Stories

2019 Chevrolet Silverado 1500 with 43,000 miles in a 'Salt Belt' state has intermittent, then total, power steering loss.

While driving, the 'Service Power Steering' and 'Service Brake Controller' messages appeared, and the steering became extremely heavy. The issue was intermittent at first, then became permanent.

Outcome: The braided body-to-frame ground strap (near the passenger front wheel) had completely corroded and broken. The owner replaced the strap with a new, sealed automotive wire for under $20. This immediately restored power steering function and cleared all related codes.

Lesson: On a 2019-2022 GM truck/SUV, a sudden loss of power steering with code C1597 is almost certainly a failed ground strap, as documented in TSB PIT6088. Do not replace the expensive power steering rack or module until this simple, cheap fix is ruled out.

2018 Ram 1500 owner swaps to winter tires and gets a C1597 code and 'Service TPM System' message.

Shortly after installing a set of aftermarket wheels with winter tires, the TPMS warning light flashed and then stayed on. On the next startup, the light was off, but the tire pressure display showed dashes '---' and a C1597 code was stored.

Outcome: Forum research revealed this is normal operation. The aftermarket winter wheels did not have TPMS sensors, so the truck entered 'Winter Mode' and set the informational C1597 code. When the original wheels with sensors were reinstalled in the spring, the code cleared itself after driving for 15 minutes above 15 mph, and the TPMS system began working normally again.

Lesson: On many Dodge/Ram/Jeep vehicles, C1597 is not a fault. It is an intentional feature to prevent annoying warnings when using wheels without TPMS sensors. No repair is needed unless you want TPMS functionality with your second set of wheels.

2020 GMC Sierra owner experiences intermittent power steering loss, but the ground straps appear visually intact.

Power steering fails randomly, sometimes multiple times on a single trip, making the truck feel unsafe. A visual check of the ground straps showed no obvious green corrosion or breakage.

Outcome: The multimeter showed a voltage drop of over 300mV (0.3V), well above the acceptable limit of 100mV (0.1V). Even though the ground strap looked okay, high resistance had built up internally and at the connection points. Cleaning the contact points to bare metal and replacing the strap resolved the voltage drop and fixed the power steering issue permanently.

Lesson: Corrosion creates high resistance that isn't always visible. A voltage drop test is the definitive way to confirm a bad ground. A reading over 0.1V on a ground circuit indicates a problem that must be fixed.

How to Prevent This Code From Triggering

• Apply Corrosion Inhibitor to Ground Connections (GM) (Once, or every 2-3 years in Salt Belt regions.) — After cleaning a ground connection to bare metal, applying a coating of dielectric grease or a dedicated corrosion inhibitor spray (like Boeshield T-9 or Fluid Film) seals the metal from moisture and oxygen. This prevents the galvanic corrosion that causes high resistance and leads to the C1597 power steering failure.
• Upgrade Braided Ground Straps (GM) (When replacing a failed strap.) — The original equipment braided straps are uninsulated and highly susceptible to corrosion. Replacing a failed strap with a sealed, insulated automotive wire of the same gauge offers significantly better protection from road salt and moisture, greatly extending the life of the repair.
• Replace All TPMS Sensors Proactively (Dodge/Ram/Jeep) (Every 7-10 years or 100,000 miles.) — TPMS sensor batteries have a finite lifespan of 5-10 years. Replacing all four sensors when you get new tires around the 7-10 year mark prevents the scenario where they fail one by one, saving you multiple trips to the tire shop. This also prevents them all from dying at once and triggering the C1597 code.
• Maintain Proper Tire Inflation Manually (Monthly.) — For Dodge/Ram/Jeep owners who use winter wheels without sensors, the TPMS system is disabled. Manually checking tire pressure monthly with a quality gauge is critical to catch slow leaks, ensure proper tire wear, maintain fuel economy, and prevent a dangerous blowout.
• Ensure Negative-Post Grounding (During any battery or electrical work.) — Modern vehicles use a negative ground system where the car's chassis connects to the battery's negative terminal. This provides a source of free electrons that acts as cathodic protection, slowing the natural rusting (oxidation) of the steel frame. Ensuring all grounds go to the chassis/negative path is critical for long-term corrosion prevention.

Frequently Asked Questions

Why did my power steering suddenly stop working on my 2020 Silverado?

On 2019-2022 models, a corroded or loose main ground strap interrupts power to the electric power steering module. This causes the module to shut down and set code C1597. Refer to GM TSB PIT6088 for the exact ground locations.

I put my winter tires on my Ram truck and now I have a C1597 code. Is something broken?

No, nothing is broken. Your truck entered 'Winter Mode' because your winter wheels lack TPMS sensors. The system reactivates automatically after you drive for 15 minutes above 15 mph with the original sensor-equipped wheels.

What is the biggest mistake when diagnosing C1597 on a GM truck?

The most costly mistake is replacing the Power Steering Control Module (PSCM) without testing the main ground straps (G132, G133). The root cause is almost always a simple ground connection with high resistance. Always perform a voltage drop test before condemning the module.

Why didn't my TPMS light come on right away after putting on my winter wheels?

On Dodge/Ram/Jeep vehicles, the system must confirm all four sensors are missing before entering 'Winter Mode'. This requires driving over 15 mph for 10-20 minutes. Once the criteria are met, the system deactivates and the light stays off on subsequent key cycles.

Is it safe to drive with code C1597?

If you have a GM truck, it is not safe because sudden loss of power steering causes severe control issues. If you have a Dodge/Ram/Jeep, the vehicle is mechanically safe to drive. However, you lose low tire pressure warnings, increasing blowout risks.

How much does it cost to fix a C1597 code?

For a GM truck, fixing a bad ground costs $150-$250 at a shop or $20 DIY. For a Dodge/Ram/Jeep, installing four new TPMS sensors costs between $220 and $475. Replacing a faulty RFH module on a Ram costs $425-$600.

Can I fix a bad ground wire myself?

Yes, if you are comfortable with basic auto repair. Locate the ground strap, disconnect the battery, clean all connection points to bare metal, and re-secure it tightly. Apply dielectric grease to prevent future corrosion.

Will clearing the C1597 code fix my power steering?

No. On a GM vehicle, C1597 is a hard fault caused by a physical loss of power. The code returns instantly until the underlying electrical problem is repaired.

Key Takeaways

• Code C1597 means one of three things: a critical power steering failure on GM trucks, a harmless TPMS 'Winter Mode' on Dodge/Ram/Jeep, or a rare VGRS error on Toyota/Lexus.
• On 2019-2022 GM trucks, C1597 is almost always a corroded ground strap (TSB PIT6088), requiring a $20 fix rather than a $2,500 steering rack replacement.
• On Dodge, Ram, and Jeep vehicles, C1597 intentionally disables the TPMS system when you install winter wheels without sensors, requiring no repair.
• Perform a voltage drop test on the GM Power Steering Control Module ground circuit; a reading above 0.1V confirms a bad ground strap.
• Do not drive a GM truck with an active C1597 code, as sudden loss of power steering at low speeds causes severe accident risks.