OBD-II Code U1110: Lost Communication With ABS Control Module

What Does U1110 Mean?

Your car's main computer, the Powertrain Control Module (PCM), has lost its data connection with the Anti-Lock Brake System (ABS) module. These computers constantly talk to each other over a network called the Controller Area Network (CAN) bus. When the PCM stops receiving data from the ABS module, it loses the vehicle speed signal required to manage engine timing, transmission shifting, and cruise control.

Technical definition: The formal OBD-II definition for this code is "Lost Vehicle Speed Message." This means the Powertrain Control Module (PCM) did not receive the expected vehicle speed signal from the Anti-lock Brake (ABS) Module over the Controller Area Network (CAN) bus. This is a one-trip fault, meaning the code sets the first time the error is detected.

Can I Drive With U1110?

Yes, But With Caution. Yes, but with extreme caution and for short distances only. Your anti-lock brakes (ABS) and stability control are disabled, increasing braking distances and the risk of skidding. Your speedometer will likely stop working, forcing the automatic transmission into a harsh-shifting limp mode. Driving long-term without a speed signal causes unnecessary wear on transmission clutches, leading to premature failure.

Common Causes

• Low battery voltage or a failing alternator (Very Common) — Modern vehicle computer modules are highly sensitive to voltage drops. A weak battery or a failing alternator causes modules to shut down and stop communicating, triggering a U1110 code before any mechanical parts actually fail.
• Blown fuse for the ABS module (Very Common) — The ABS module relies on dedicated power fuses (often 30A or 40A). If a fuse blows due to a power surge or short, the module loses power and drops off the CAN bus network entirely.
• Damaged, corroded, or loose wiring/connectors (Common) — CAN bus wires and ABS connectors are exposed to moisture, road salt, and vibration. A corroded pin, a loose connector, or a wire severed by road debris breaks the communication link between the ABS module and the PCM.
• Failed Anti-Lock Brake (ABS) Module (Common) — The ABS module fails internally due to circuit board degradation, a burnt microprocessor, or water intrusion. When this happens, it stops sending the vehicle speed signal to the rest of the network.
• Faulty Wheel Speed Sensor (Less Common) — A wheel speed sensor that shorts out or sends wildly erratic data overloads the ABS module, causing it to stop communicating properly with the PCM and triggering a U1110 code alongside a 'C' series chassis code.
• Faulty Clockspring (Less Common) — The steering column clockspring is part of the vehicle's CAN network. Its failure disrupts bus communication, leading to U1110, often accompanied by U1120 (Lost Wheel Distance Message).
• Improperly Installed Aftermarket Electronics (Rare) — Aftermarket radios, alarms, or remote starters spliced incorrectly into the CAN bus create data collisions, blocking the ABS module's speed signal from reaching the PCM.
• Faulty Powertrain Control Module (PCM) (Rare) — The main computer (PCM) rarely fails in a way that isolates a single communication channel. This is the absolute last component to suspect after ruling out power, ground, wiring, and the ABS module.

Symptoms

• Check Engine Light is on — The PCM illuminates the Check Engine Light immediately upon losing the speed signal.
• ABS and Traction/Stability Control warning lights are on — Because the ABS module is offline, the dashboard warning lights for ABS, ESP, and Traction Control illuminate simultaneously.
• Speedometer does not work — The PCM relies on the ABS module for vehicle speed data. Without this signal, the speedometer drops to zero.
• Harsh or incorrect automatic transmission shifting — The transmission control module requires vehicle speed to calculate shift points. Without it, the transmission enters 'limp mode,' causing erratic, delayed, or violent shifts.
• Cruise control is disabled — Cruise control requires a steady vehicle speed signal. The system disables itself entirely when U1110 is active.
• Vehicle cranks but will not start — If the ABS module suffers a catastrophic internal short, it pulls down the entire CAN bus network, preventing the PCM from firing the spark plugs or fuel injectors.

Diagnostic Flowchart

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

Common Fixes & Costs

• Replacing a Blown ABS Fuse — Parts: $1-$5, Labor: $0, ~0.1 hr book time (DIY)
• Repairing Damaged Wiring or Connectors — Parts: $10-$50, Labor: $200-$800, ~2.5 hr book time (Intermediate)
• Replacing the ABS Module — Parts: $300-$800, Labor: $150-$400, ~2 hr book time (Professional)
• Updating or Reprogramming Module Software — Parts: $0, Labor: $100-$300, ~1 hr book time (Professional)
• Replacing the Powertrain Control Module (PCM) — Parts: $500-$1,500, Labor: $150-$500, ~1.5 hr book time (Professional)

DIY vs Professional

• Replacing a Blown ABS Fuse — Beginner:
  Tools: Owner's manual, fuse puller or pliers.
• Repairing Damaged Wiring or Connectors — Beginner:
  Tools: Multimeter, wiring diagram, wire cutters/strippers, soldering iron, heat shrink tubing, flashlight.
• Replacing the ABS Module — Beginner:
  Tools: Advanced OBD-II scanner, vehicle-specific software, socket set, torque wrench.
• Updating or Reprogramming Module Software — Beginner:
  Tools: Manufacturer-specific diagnostic tool and software subscription.

Used vs. New Parts: Buying Guide

When a used part is worth it: A used ABS module makes sense for vehicles over 10 years old where a new part is prohibitively expensive or discontinued, provided you can source one from a non-rust-belt state with a 30-day warranty.

Donor-vehicle mileage cap: roughly under 100000 miles for the part to have meaningful remaining life.

Donor quality checklist:

• Match the part number exactly. Do not rely on year/make/model alone.
• Avoid modules from vehicles in regions with heavy road salt use.
• Ensure the seller offers at least a 30-day warranty.

Decision logic:

• If You have your original module and the failure is internal → Send it to a specialized electronics rebuilder. This requires no programming upon return.
• If Vehicle is less than 10 years old and a new part is available → Buy a new or remanufactured part with a 1-year to lifetime warranty.
• If Vehicle is older and budget is the primary concern → Buy a used module, but factor in the $100-$150 cost of dealer programming.

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

Worst-case if a used part fails: $300-$600. If a used module fails, you pay for labor and programming a second time.

What Happens If You Wait — Timeline

1. Immediate: Check Engine, ABS, and Stability Control lights illuminate. Speedometer and cruise control stop working. (MPG impact: 0-5%% · Added cost: $0)
2. 1-4 weeks: The transmission shifts harshly as it operates in 'limp mode.' Fuel economy decreases as the PCM uses default values instead of actual speed. (MPG impact: 5-15%% · Added cost: $20-$80 in wasted fuel.)
3. 1-6 months: Constant high-pressure shifts cause accelerated wear on internal transmission clutches and solenoids. The vehicle fails state safety inspections. (MPG impact: 10-20%% · Added cost: $150-$500 in inspection failure fees and accumulating transmission wear.)
4. 6+ months: Severe internal transmission damage occurs, leading to complete failure where the vehicle will not move. (MPG impact: N/A% · Added cost: $2,500-$5,000+ for transmission replacement.)

Cost of Not Fixing It

• Immediate: Loss of ABS and stability control creates a significant safety risk. You will fail a state safety inspection. (Added cost: $50-$250 in traffic fines or inspection fees.)
• 0-3 months: Harsh shifting due to the lack of a speed signal causes premature wear on transmission clutches and solenoids. (Added cost: $0, but internal transmission wear is accumulating rapidly.)
• 3+ months: Severe wear leads to complete transmission failure. The lack of a speed signal forces the transmission into a high-pressure 'limp mode,' destroying internal components. (Added cost: $2,500-$5,000 for transmission rebuild or replacement.)

Diagnosis Steps

1. Check and Charge the Battery
   Test the battery's voltage with a multimeter; it must be above 12.4 volts with the engine off. A reading below 9.7 volts causes the ABS module to shut down. Charge the battery if it's low and test the alternator output (should be 13.5V-14.5V running).
   Tools: Multimeter, Battery Charger (Beginner)
2. Inspect All ABS Fuses
   Locate the fuse box using your owner's manual. Find all fuses powering the ABS module (often multiple 30A or 40A fuses). Visually inspect them for breaks. Replace any blown fuse with the exact same amperage.
   Tools: Owner's Manual, Fuse Puller or Pliers (Beginner)
3. Scan All Vehicle Modules
   Use a full-system OBD-II scanner to read codes from the ABS, TCM, and BCM. Code U0121 frequently accompanies U1110 and confirms the ABS module is completely offline. 'C' codes indicate a specific wheel speed sensor fault that must be fixed first.
   Tools: OBD-II Scanner (multi-system capable) (Beginner)
4. Visually Inspect Wiring and Connectors
   Trace the wiring harness from the ABS module. Look for corroded connectors (green crust), chewed wires, or loose connections. Disconnect the main ABS module plug and inspect for bent pins or water intrusion.
   Tools: Flashlight (Intermediate)
5. Verify Power and Ground at the ABS Module
   Unplug the ABS module. Using a multimeter and wiring diagram, check the power supply pins with the key on; you must see 12V+. Check the ground pins for resistance to the chassis; it must be less than 1 ohm. Missing power or ground is the primary cause of module offline status.
   Tools: Multimeter, Vehicle-specific Wiring Diagram (Advanced)
6. Test CAN Bus Resistance
   Disconnect the battery. Measure resistance between CAN High (Pin 6) and CAN Low (Pin 14) at the OBD-II port. It must read exactly 60 ohms. A reading of 120 ohms means a terminating resistor (often inside the ABS module) is offline or the circuit is open. A reading of 0 ohms means the CAN wires are shorted together.
   Tools: Multimeter (Advanced)
7. [PRO TIP] Isolate the ABS Module
   If you suspect the ABS module is shorting the network (especially in a no-start scenario), unplug its main connector. Re-test the CAN bus resistance at the OBD-II port or try starting the car. If resistance returns to normal or the car starts, the ABS module has an internal short and requires replacement.
   Tools: Basic hand tools to access ABS module (Advanced)
8. [PRO TIP] Load Test the Power Circuit
   A corroded wire shows 12V on a multimeter but fails under load. Connect an old headlight bulb to the ABS module's power and ground pins on the harness side. If the bulb lights up brightly, the circuit handles current properly. If it is dim, trace the wire for high resistance.
   Tools: Old headlight bulb with wires, Multimeter, Wiring Diagram (Professional)

When This Code Triggers (Freeze-Frame Conditions)

• Vehicle Speed: 0 mph or an erratic value (The freeze frame logs a vehicle speed of 0 mph or a nonsensical value at the exact moment the fault occurs, confirming the lost data.)
• System Voltage: 13.5-14.5V (or <11V) (Voltage in the normal charging range indicates a wiring/module fault. Voltage below 11V points directly to a battery or alternator issue.)
• Engine Coolant Temp: 180-200°F (The fault often occurs when the vehicle is fully warmed up, as heat expansion exacerbates loose connections or failing circuit boards.)

Related Codes

• U0121 — "Lost Communication With Anti-Lock Brake System (ABS) Control Module." U0121 indicates the ABS module is completely offline, while U1110 specifies the vehicle speed message is missing. If both are present, diagnose U0121 first by checking ABS power and ground.
• U1120 — "Lost Wheel Distance Message." Frequently appears with U1110 in Chrysler/Dodge/Jeep vehicles. Seeing both confirms the fault lies with the ABS module or its network connection.
• P0500 — "Vehicle Speed Sensor 'A' Malfunction." Set by the PCM when it determines the vehicle speed signal is missing. It appears as a direct consequence of the U1110 code.
• C-Series Codes (e.g., C1020) — Any 'C' code indicates a specific fault within the chassis system. A shorted wheel speed sensor causes the entire ABS module to stop communicating, triggering U1110. Always fix 'C' codes first.

Climate & Environmental Factors

• High Humidity and Rain: Moisture penetrates weathered connector seals, leading to corrosion and short circuits. This is a primary cause of communication failures over time.
• Winter Conditions (Snow, Ice, Road Salt): Road salt and de-icing brines accelerate the deterioration of copper wires and connector pins, especially on frame-mounted ABS modules.
• Extreme Cold: Cold weather lowers battery voltage, making it insufficient to power all modules correctly, which triggers communication codes.

How to Talk to a Mechanic About This Code

Say this: "I have a U1110 code with the ABS and Check Engine lights on. I'd like to schedule a diagnostic for a CAN bus communication failure. Please verify power, ground, and network wiring to the ABS module before recommending a module replacement."

This directs the technician to perform a proper electrical diagnosis to find the root cause (often wiring or fuses) instead of immediately suggesting a $1,000 ABS module replacement.

Avoid saying:

• 'My ABS light is on, can you fix it?'
• 'Just replace the ABS computer.'
• 'I have a U-code, I don't know what it means.'

Questions to ask before authorizing the repair:

• Did you find the failure in the wiring, or is the module itself bad?
• What were the voltage and ground readings at the ABS module connector?
• What was the resistance on the CAN bus, and did you isolate the module to find the fault?
• Does the new module require programming, and is that included in the estimate?

Where to Take It: Dealer vs Independent vs Chain

• Dealer:
  Best for: Vehicles under warranty, Confirmed software issues or TSBs (like Toyota models), Programming a brand new ABS module
  Downsides: Highest labor rates., Quick to replace entire modules rather than perform detailed wiring repairs. (Typical cost: +50% vs. baseline)
• Independent Shop: Best fit for most scenarios. A good independent diagnostic shop handles wiring faults effectively and more affordably than a dealer.
  Best for: Out-of-warranty vehicles where the cause is likely wiring, a fuse, or a module swap., Shops with strong electrical and diagnostic reputations (ASE certified).
  Downsides: May lack access to the latest manufacturer software for programming new modules. (Typical cost: +0% vs. baseline)
• Chain Shop: AVOID. Complex electrical diagnosis is beyond the scope of most chain shops.
  Best for: Simple, pre-diagnosed fixes like replacing a wheel speed sensor.
  Downsides: Not equipped for in-depth network diagnostics., High risk of misdiagnosis and unnecessary parts replacement. (Typical cost: -10% vs. baseline)

When to Walk Away From the Repair

If the estimated repair cost exceeds 40-50% of the car's private-party value, sell or trade in the vehicle instead of repairing it.

• Car worth $4000, fix is $1800: Walk away. The repair cost is 45% of the car's value.
• Car worth $15000, fix is $1800: Fix it. The repair cost is 12% of the vehicle's value and is a worthwhile investment in safety.
• Car worth $2500, fix is $1500: Walk away. The repair cost is 60% of the car's value.

What Scan Tool You Need for This Code

Minimum: A scanner that reads codes from all vehicle modules, specifically the Anti-Lock Brake (ABS) system (advertised as 'ABS/SRS' or 'All System').

A basic $20 code reader only communicates with the PCM. It sees U1110 but cannot read the critical codes stored inside the ABS module (like U0121 or C-codes) required for diagnosis.

Budget: BlueDriver Pro (~$100) — Reads and clears codes from all modules, including ABS, showing the full picture of network faults.

Mid-range: Foxwell NT630 Plus (~$150) — Provides full ABS system diagnostics and shows live data from wheel speed sensors.

Professional: Autel MaxiCOM MK808S (~$500) — Offers full-system diagnostics and bidirectional controls to actively test components and isolate faulty modules.

Rent vs buy: For a one-time diagnosis, borrow a free ABS-capable scanner from an auto parts store. If their tool is too basic, buying the BlueDriver is cheaper than a shop's diagnostic fee.

How to Clear the Code After You Fix It

1. Reconnect the battery if it was disconnected.
2. Use a full-system OBD-II scan tool to erase U1110 from the PCM and related codes (U0121, C-codes) from the ABS module.
3. Perform a standard drive cycle to verify the repair.

Drive cycle (~20 minutes): Start the vehicle cold and idle for 3 minutes. Drive in stop-and-go traffic for 10 minutes, including complete stops. Drive at a steady highway speed (55 mph) for 10 minutes. The warning lights remain off if the repair is successful.

Readiness monitors affected: Clearing the code resets all emissions monitors to 'Not Ready' status, though the network fault itself does not directly block emissions components.

Before emissions retest: drive at least 50 miles to fully set monitors.

Watch out for:

• Disconnecting the battery clears the PCM but does not erase codes stored in the ABS module memory on many modern vehicles.
• Using a basic $20 code reader fails to clear the root fault stored in the ABS module.

Will This Fail Emissions / State Inspection?

Yes — this code typically fails an OBD-II emissions inspection.

• California: An illuminated Check Engine Light is an automatic failure for a smog check. The U1110 code must be resolved and monitors set to 'Ready'.
• New York: The NYS safety inspection checks for illuminated ABS and Check Engine lights. Either light causes an automatic failure.
• Texas: In emissions counties, the Check Engine Light causes failure. In all counties, an illuminated ABS light fails the safety inspection.

Most Commonly Affected Vehicles

• Dodge Grand Caravan (2009-2016) — Prone to wiring harness issues near the ABS module and TIPM (fuse box) failures that cause communication codes. Connector C335 is a common point of corrosion.
• Ram 1500 (2008-2018) — Frequently experiences this code due to corroded wiring to the ABS module, especially the harness section near the driver's side front wheel well which is susceptible to road debris.
• Jeep Liberty (2007-2012) — Often sees this code combination when a wheel speed sensor fails or wiring is damaged. Owners report tachometer failure in addition to the speedometer.
• Chrysler 300 (2006-2010) — Wiring harness problems and internal ABS module failures are common culprits. Often appears with U0121.
• Jeep Patriot (2014-2017) — Appears after battery-related events like jump-starts, or due to underlying ABS module faults. A full system scan is crucial.
• Toyota Corolla (2016-2019) — U1110 is commonly caused by a software glitch in the Entune infotainment system, not the ABS. The fix is a dealer-installed software update per TSB T-SB-0024-20.
• Chevrolet Silverado 1500 (2007-2014) — Known for premature failure of the frame-mounted ABS control module due to water and salt exposure.
• Volkswagen Routan (2009-2014) — As a rebadged Dodge Grand Caravan, it suffers the exact same TIPM fuse box and ABS wiring harness failures. Check the ABS power fuses first.

Manufacturer-Specific Notes

• Chrysler/Dodge/Jeep/Ram: Highly susceptible to this code due to faulty TIPMs (fuse boxes), wiring harness corrosion, or internal ABS module failures. Multiple recalls exist for ABS module software malfunctions, such as 24V-653 for 2019-2024 Ram 1500s.
• Toyota: On 2016-2019 Corollas and 2016-2017 Camrys, U1110 is a manufacturer-specific code for "Lost Communication with Multimedia/Radio Head Unit." It is fixed via a radio software update (TSB T-SB-0024-20), not brake repairs.
• Ford: Often defined as "SCP (J1850) Invalid or Missing Data for Primary Id." It points to a communication network failure requiring visual inspection of the ABS module connections and CAN bus wiring.
• General Motors (GM): A failing ABS module is the most common cause. The module is mounted to the frame rail under the driver's side, exposing it to water and salt that corrodes the internal circuit board.

Real Owner Stories

2010 Dodge Grand Caravan at 130K miles - The Easy Fix

ABS, ESP, and Brake lights came on suddenly, followed by the Check Engine light. Codes U1110, U0121, and U1120 were present.

Outcome: Found a blown 30A fuse for the ABS module. Replacing the $3 fuse cleared all lights and codes.

Lesson: Always check the simple solutions first. A single blown fuse mimics a catastrophic module failure. Chrysler/Dodge vehicles utilize multiple fuses for the ABS system.

2007 Ram 1500 - The Misdiagnosis Story

ABS light on and speedometer dead. Codes U1110 and U0121 appeared.

Outcome: A visual inspection revealed road debris had smashed the wiring connector leading to the ABS module in the wheel well. Splicing in a $30 pigtail connector fixed the issue.

Lesson: Do not assume the most expensive part failed. Physical damage to wiring is highly common on trucks. A thorough visual inspection saves hundreds of dollars.

2015 Jeep Patriot at 174K miles - The No-Start Nightmare

Engine cranked but would not start. Codes U1110 and U1120 were present. Fuses and fuel pump were good.

Outcome: The ABS module suffered an internal short, pulling down the entire CAN bus network and preventing the PCM from firing the spark plugs. Unplugging the ABS module restored network communication and allowed the vehicle to start, confirming the module was bad.

Lesson: A shorted ABS module prevents your car from starting. If you have a no-start condition with communication codes, unplug the suspect module to see if the engine starts.

How to Prevent This Code From Triggering

• Clean and Protect Electrical Connectors (Every 2-3 years) — Unplugging critical connectors, cleaning them with contact cleaner, and applying dielectric grease seals out moisture and prevents corrosion-induced communication failures.
• Maintain Battery Health (Annually) — Low voltage causes modules to malfunction. Clean battery terminals and test the battery annually after it reaches 3 years of age.
• Apply Undercarriage Protectant in Salt-Belt Regions (Annually before winter) — Road salt destroys electrical components. Applying a wax-based undercoating protects frame-mounted modules and wiring from corrosive brines.

Frequently Asked Questions

What is the first thing I should check for a U1110 code?

Start by testing your battery's voltage and inspecting all fuses related to the ABS module. A weak battery or a single blown fuse are the most common, easy-to-fix causes.

Can a bad wheel speed sensor cause a U1110 code?

Yes. If a wheel speed sensor shorts out, it overloads the ABS module and stops it from communicating with the PCM, triggering the U1110 code. If you have a wheel-speed-sensor-specific 'C' code, fix that first.

Is it safe to drive my car with the U1110 code?

It is not recommended for anything other than a short trip to a repair shop. Your anti-lock brakes and stability control are disabled, and the lack of a speedometer forces the transmission into a damaging limp mode.

Why did my speedometer and tachometer stop working with this code?

The Powertrain Control Module (PCM) gets the vehicle speed reading from the ABS module. When U1110 sets, the PCM loses that connection and cannot operate the speedometer. In some Jeeps, this network failure also kills the tachometer signal.

What are the most common misdiagnosis mistakes for a U1110?

A common mistake is immediately replacing the ABS module without performing a full electrical diagnosis. The true cause is often a simple wiring, connector, or power supply issue. Always check for TSBs and diagnose power, ground, and network wiring before condemning a $500+ module.

Can I just clear the code?

You can clear it, but the code returns instantly as soon as the PCM detects the missing communication again.

How much will it cost to fix the U1110 code?

A simple fuse replacement is under $5, while a wiring repair costs $200-$800. If the ABS module requires replacement and programming, the total cost ranges from $450 to over $1,200 depending on the vehicle.

What does it mean if my car won't start and I have a U1110 code?

If the U1110 code is present along with a no-start condition, the faulty ABS module or its wiring has shorted out the entire CAN bus network. This prevents essential modules like the PCM from communicating, stopping the engine from cranking. Unplug the ABS module; if the car starts, the module is the culprit.

Key Takeaways

• Code U1110 triggers when the Powertrain Control Module (PCM) loses the vehicle speed signal from the Anti-Lock Brake System (ABS) module over the CAN bus.
• Always test the battery (must be >12.4V) and inspect the 30A/40A ABS fuses before replacing expensive parts, as low voltage causes 30% of communication errors.
• Expect an illuminated Check Engine Light, disabled ABS/traction control, and a dead speedometer, which forces the transmission into a harsh-shifting limp mode.
• Do not drive the vehicle long distances; the lack of a speed signal causes harsh transmission shifts that result in a $2,500+ transmission failure within months.
• Check for Technical Service Bulletins (TSBs) before diagnosing the brakes; on 2016-2019 Toyotas, U1110 actually indicates a radio software glitch requiring a $100-$300 dealer update.