OBD-II Code P1389: Auto Shutdown (ASD) Relay Circuit Malfunction

What Does P1389 Mean?

P1389 means the Powertrain Control Module (PCM) commanded the Auto Shutdown (ASD) relay to turn on, but detects no power on the confirmation circuit. The ASD relay is a master switch powering the fuel injectors, ignition coils, and fuel pump. When the PCM detects missing voltage, it logs the code and disables the engine to prevent damage.

Technical definition: No Auto Shutdown (ASD) Relay Output Voltage At PCM. The PCM energizes the ASD relay but senses zero voltage on the ASD relay output sense circuit. This check runs when battery voltage exceeds 10.4 volts.

Can I Drive With P1389?

No — Do Not Drive. The vehicle will likely not start. If it does start, the engine shuts off without warning at any time, including at highway speeds. This causes a sudden loss of power steering and brakes, creating a severe and immediate safety risk. Do not drive the vehicle.

Common Causes

• Faulty Auto Shutdown (ASD) Relay (Very Common) — The relay is a mechanical switch and a frequent failure point. Internal contacts burn, corrode, or wear out, and the internal coil breaks, preventing it from switching power on correctly.
• Blown ASD Fuse or Fusible Link (Common) — The ASD relay circuit is protected by a fuse. If this fuse blows due to a short or overload, the relay cannot send power to the engine components, instantly triggering the code.
• Damaged Wiring or Connectors (Common) — Wires between the PCM, the Power Distribution Center (PDC), and the ASD relay corrode, short, or break. This frequently occurs at the PCM connector, the relay socket, or where rodents chew through the harness.
• Faulty Powertrain Control Module (PCM) (Less Common) — The internal driver circuit within the PCM that controls or senses the ASD relay fails. On many Chrysler, Dodge, and Jeep vehicles, this known issue overheats and melts the C3 PCM connector (specifically pin 12).
• Faulty Crankshaft or Camshaft Position Sensor (Less Common) — The PCM only keeps the ASD relay energized if it receives a valid RPM signal from the crank and cam sensors. A sensor failure forces the PCM to shut down the ASD relay, logging P1389 as a secondary fault.
• Poor Grounds (Uncommon) — Corroded or loose ground straps for the engine block, chassis, or PCM create electrical voltage drops that force the PCM to incorrectly flag a P1389 code.
• Low Battery Voltage (Uncommon) — Battery voltage below 10.4 volts or a failing alternator disrupts the PCM's ability to monitor the ASD circuit. A healthy battery must measure 12.4-12.8V at rest.

Symptoms

• Engine cranks but will not start — The starter turns the engine over, but it will not fire because the ASD relay cuts power to the ignition coils and fuel injectors.
• Engine stalls unexpectedly — The vehicle starts and runs before suddenly shutting off without warning. This happens while driving or idling.
• Check Engine Light is on — The PCM illuminates the Malfunction Indicator Lamp (MIL) immediately upon detecting the fault.
• Rapidly clicking relays in the fuse box — When the fault is intermittent or caused by a failing sensor or bad ground, the ASD relay clicks rapidly as the PCM struggles to energize the circuit.
• No spark and no fuel injector pulse (also visible on scanner) — A fault results in zero spark from the ignition coils and no signal to the fuel injectors, verifiable with a noid light or spark tester.

Diagnostic Flowchart

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

Common Fixes & Costs

• Replace the ASD Relay — Parts: $10-$30, Labor: $0-$50, ~0.2 hr book time (DIY)
• Replace Blown ASD Fuse — Parts: $1-$5, Labor: $0, ~0.1 hr book time (DIY)
• Repair Wiring or Connectors — Parts: $5-$50, Labor: $150-$450, ~2.5 hr book time (Professional)
• Replace Powertrain Control Module (PCM) — Parts: $250-$800, Labor: $150-$300, ~1.5 hr book time (Professional)
• Repair PCM Connector Pin — Parts: $10-$30, Labor: $120-$250, ~1.5 hr book time (Professional)

DIY vs Professional

• Replace ASD Relay / Fuse — Beginner:
  Tools: None, or a fuse puller.
• Repair Wiring — Beginner:
  Tools: Multimeter, wire cutters/strippers, crimpers, heat shrink tubing.
• Replace PCM — Beginner:
  Tools: Basic socket set.

Used vs. New Parts: Buying Guide

When a used part is worth it: A used PCM from a salvage yard is a high-risk option. It makes sense only if the budget is extremely tight and the vehicle is old. A professionally remanufactured unit from a reputable supplier is the safest middle-ground.

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

Donor quality checklist:

• Verify the donor vehicle's VIN to ensure compatibility (engine, transmission, and emissions options).
• Avoid PCMs from vehicles with flood or fire damage.
• Demand a short-term warranty (30-90 days) even from a salvage yard.

Decision logic:

• If The original fault was a shorted wire that has now been fixed → A new or quality remanufactured PCM is the safest bet to avoid immediate failure.
• If The PCM requires programming to the vehicle's VIN and security system → Buy from a remanufacturer that offers pre-programming ('plug-and-play') service to avoid a trip to the dealer.

Warranty tradeoff: Used parts often have a 30-day warranty. Remanufactured PCMs typically come with a 1-year to limited lifetime warranty. New OEM parts carry a 1-2 year warranty but are the most expensive.

Worst-case if a used part fails: $600-$1800 if a faulty replacement PCM is installed on a vehicle with a pre-existing short. The short destroys the replacement PCM instantly.

What Happens If You Wait — Timeline

1. 0-1 month: Intermittent fault. The engine stalls once and runs fine for weeks, or has a single crank-no-start event. The Check Engine Light turns on and off. (MPG impact: 0-1% (Negligible impact, reliability is the main concern)% · Added cost: $0-$150 (Potential towing cost))
2. 1-4 months: Fault becomes frequent. Stalling or no-start events happen weekly. Repeated on/off power cycling stresses the PCM's internal components. (MPG impact: 1-3% (Slightly affected by rough running)% · Added cost: $150-$450 (Multiple towing events))
3. 4-8 months: A persistent short generates significant heat. The ASD relay socket or the wiring harness near the PCM feels hot. Insulation on the ASD sense wire breaks down. (MPG impact: N/A (Vehicle is likely too unreliable to drive)% · Added cost: $250-$750 (Cost of a wiring harness repair. Risk of PCM damage increases significantly.))
4. 8+ months: Catastrophic failure. The short circuit overheats and melts the PCM connector, destroying the internal driver circuit in the PCM. The vehicle is permanently disabled. (MPG impact: N/A (Vehicle is inoperable)% · Added cost: $800-$2000+ (Cost of a new PCM, programming, and labor to repair the melted connector.))

Cost of Not Fixing It

• Immediate: Vehicle is unreliable, will not start, or stalls at any time, creating a severe safety risk. (Added cost: $100-$300 (Towing costs))
• 1-3 months: Attempting to drive with an intermittent fault causes rapid on/off cycling of power to the PCM, generating voltage spikes that destroy the computer. (Added cost: $500-$1000 (Cost of a new PCM))
• 3+ months: A persistent short in the ASD circuit overheats wiring, melting the PCM connector harness. This requires de-pinning and replacing the connector. (Added cost: $250-$500 (Additional labor to repair a melted wiring harness))

Diagnosis Steps

1. Swap the ASD Relay (The 'Horn Trick')
   Find an identical relay in the fuse box that controls a non-essential system (like the horn). Swap this relay with the ASD relay. If the car starts, the original ASD relay is bad and requires replacement.
   Tools: None (Beginner)
2. Perform a Visual Inspection
   Locate the ASD relay and its fuse in the under-hood fuse box. Inspect the fuse to see if it is blown. Check the relay socket for scorching, melting, or corrosion. Inspect the surrounding wiring for chafing or rodent damage.
   Tools: Flashlight (Beginner)
3. Check for Power at the Relay Socket
   Remove the ASD relay. With the key 'ON', use a multimeter to check for battery voltage at the terminals in the socket. One terminal must have constant 12V+ power, and another gets 12V+ when the key turns on.
   Tools: Multimeter (Intermediate)
4. Check the PCM Control Signal (Ground)
   Identify the control terminal in the relay socket. Connect a test light to battery positive and probe this terminal. Have an assistant turn the key to 'ON'. The test light must illuminate for 2 seconds as the PCM primes the system.
   Tools: Multimeter or 12V test light, assistant, vehicle-specific wiring diagram (Intermediate)
5. Test the ASD Output Sense Circuit
   With the battery disconnected, use a multimeter set to Ohms to check continuity on the ASD output sense wire from the relay socket (often terminal 87) to the PCM connector (often pin 12 on Dodge/Jeep). Resistance must be under 5 ohms. If infinite (O.L.), find and repair the broken wire.
   Tools: Multimeter, vehicle-specific wiring diagram (Advanced)
6. PRO TIP: The 'Wiggle Test'
   If the problem is intermittent, start the engine and systematically wiggle the wiring harness between the fuse box and the PCM. Tap gently on the PCM. If wiggling causes a stall, you have pinpointed a loose connection.
   Tools: None (Intermediate)
7. Check for Voltage Drop
   Reconnect everything and backprobe the ASD output sense pin at the PCM connector. With the engine running or cranking, voltage must be within 0.5 volts of the battery voltage. A larger drop indicates high resistance.
   Tools: Multimeter with backprobe pins, vehicle-specific wiring diagram (Advanced)
8. Analyze Cam/Crank Sensor Signals
   If P1389 appears with P0320 (Crank Sensor) or P0340 (Cam Sensor), diagnose those first. A missing RPM signal forces the PCM to de-energize the ASD relay after the 2-second prime.
   Tools: Oscilloscope, vehicle-specific wiring diagram (Advanced)

When This Code Triggers (Freeze-Frame Conditions)

• Engine RPM: 0 RPM (During initial key-on or crank-no-start. The PCM primes the relay but detects no output voltage before the engine fires.)
• Vehicle Speed: 25-55 mph (Intermittent stall while driving. The fault occurs due to vibration or a thermal issue, causing the relay or wiring to fail mid-drive.)
• Engine Coolant Temp: 190-210°F (Fault occurs after the engine is fully warmed up, suggesting a component fails under heat stress (e.g., PCM or wiring with compromised insulation).)

Related Codes

• P1388 — Points to a fault in the control side of the circuit (the low-current ground signal from the PCM to the relay). P1389 points to the output side. If you have P1388, focus on the PCM's command signal.
• P0320 — Indicates a Crankshaft Position Sensor signal problem. A faulty crank sensor causes the PCM to shut down the ASD relay, triggering P1389 as a secondary effect. Diagnose P0320 first.
• P0688 — Another code for the 'ASD/Main Relay Sense Circuit'. It is functionally identical to P1389 and requires the exact same diagnostic path.

Climate & Environmental Factors

• High Humidity & Rain: Moisture seeps past aging seals and creates conductive paths that lead to shorts or high resistance in the fuse box, directly causing a P1389 fault.
• Winter Conditions / Road Salt: Road salt and de-icing chemicals create a highly corrosive environment, severely accelerating the degradation of wiring harnesses and ground connections.

How to Talk to a Mechanic About This Code

Say this: "I have a crank-no-start condition with a P1389 code. I swapped the ASD relay with no change. I need a technician to perform electrical diagnostics on the ASD circuit. Please test for power and ground at the relay socket, and check the continuity of the sense wire from the fuse box to the PCM before recommending a new computer."

This directs the mechanic to follow a logical diagnostic path (relay -> wiring -> PCM) instead of jumping to the most expensive conclusion. It establishes that you refuse to pay for a new computer unless the wiring is proven good.

Avoid saying:

• 'My car won't start, can you fix it?'
• 'My check engine light is on, I think it's the computer.'
• 'Just replace the parts until it works.'

Questions to ask before authorizing the repair:

• If you recommend a PCM, did you perform a continuity and voltage drop test on the ASD sense wire? What were the readings?
• If the wiring is bad, can you show me where the break or short is located?
• If the PCM requires replacement, is there a risk that a wiring problem caused the original to fail and will damage the new one?

Where to Take It: Dealer vs Independent vs Chain

• Dealer:
  Best for: Vehicles still under powertrain warranty., When a PCM replacement is confirmed and requires manufacturer-specific programming (flashing).
  Downsides: Highest labor rates, often $150-$250/hour., Defaults to replacing an entire assembly rather than repairing a specific wire or connector. (Typical cost: +50% vs. baseline)
• Independent Shop: Best fit. An experienced independent technician performs cost-effective wiring repairs and has extensive experience with this common Chrysler-family failure.
  Best for: Out-of-warranty vehicles, especially common domestic brands like Dodge, Jeep, and Chrysler., Electrical diagnostics and wiring repairs.
  Downsides: Shop quality and diagnostic skill vary greatly; look for ASE certifications for electrical work. (Typical cost: +0% vs. baseline)
• Chain Shop: AVOID for diagnosis. A chain shop may swap the ASD relay, but they are not the right choice for tracing the complex electrical fault that P1389 represents.
  Best for: Simple, clear-cut parts replacement like a battery or alternator.
  Downsides: Technicians are rarely equipped for in-depth electrical diagnosis., High pressure to sell parts leads to misdiagnosis, such as recommending a PCM when the real issue is a broken wire. (Typical cost: -10% vs. baseline)

When to Walk Away From the Repair

If the estimated repair cost for the P1389 fault exceeds 50% of your car's private-party market value, seriously consider selling the vehicle as-is.

• Car worth $3000, fix is $1800: Walk away. The repair cost is 60% of the vehicle's value. This is not a sound financial decision.
• Car worth $10000, fix is $1800: Fix it. The repair cost is 18% of the vehicle's value and restores its primary function.
• Car worth $4500, fix is $400: Fix it. A wiring repair at this price is well below the threshold and is a smart investment.

What Scan Tool You Need for This Code

Minimum: A scanner that reads codes, clears codes, and displays live data streams, specifically Engine RPM.

A basic $20 code reader only tells you the P1389 code exists. It cannot show live Engine RPM while cranking, which is essential to rule out a faulty crankshaft position sensor. Without live data, you are flying blind.

Budget: BlueDriver Pro (~$99) — Connects to your smartphone and provides live data graphing for Engine RPM to help differentiate a crank sensor issue from a true ASD circuit fault.

Mid-range: Foxwell NT510 Elite / Innova 5610 (~$150) — Offers live data and bidirectional controls. This allows you to command the ASD relay on and off directly from the scanner, providing definitive proof of whether the control circuit works.

Professional: Autel MaxiCOM MK808S (~$400) — Provides full bidirectional control of nearly all vehicle systems, including commanding the ASD relay. Supports advanced functions like FCA AutoAuth for secure gateway access on newer Chrysler/Jeep/Dodge vehicles.

Rent vs buy: You can borrow a basic code reader from AutoZone to confirm the code. However, to properly diagnose P1389 yourself, you need live data, making buying a budget pick like the BlueDriver a worthwhile investment.

How to Clear the Code After You Fix It

1. Reconnect battery if it was disconnected for the repair.
2. Use a quality OBD-II scan tool to clear the Diagnostic Trouble Codes (DTCs).
3. Perform a complete drive cycle to allow all readiness monitors to run.

Drive cycle (~20 minutes): Cold start the vehicle and let it idle for 2-3 minutes. Drive in mixed city/highway traffic for 15-20 minutes, including steady speeds between 40-60 mph for at least 8 minutes. Allow the vehicle to cool down completely.

Readiness monitors affected: Catalyst Monitor, Evaporative System Monitor, O2 Sensor Monitor, O2 Sensor Heater Monitor

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

Watch out for:

• Disconnecting the battery clears the code but resets all readiness monitors to 'Not Ready', causing an automatic emissions failure.
• The code returns immediately if the underlying electrical fault (bad relay, broken wire, faulty PCM) remains unfixed.

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. All required readiness monitors must be 'Ready'.
• Texas: In counties requiring emissions testing, an illuminated Check Engine Light is an automatic failure. You pass a safety-only inspection, but fail the emissions test.

Most Commonly Affected Vehicles

• Jeep Grand Cherokee (1999-2004) — Extremely common on WJ models with the 4.7L V8. Often caused by PCM failure which melts the C3 connector. Fuse #6 in the PDC getting hot is a key indicator.
• Dodge Ram 1500/2500 (1998-2003) — Frequently experience P1389 due to faulty PCMs, causing the wiring harness connector to melt. The issue is often intermittent at first.
• Jeep Cherokee (XJ) (1997-2001) — Often leads to a crank-no-start condition. Rodent damage to the harness is a known issue on XJs parked for extended periods.
• Dodge Dakota / Durango (1998-2004) — Shares electronics with the Ram and is highly susceptible to the same ASD relay and PCM circuit failures.
• Ford F-250/F-350 Super Duty (7.3L Diesel) (1999-2003) — On Ford diesels, P1389 means 'Glow Plug Circuit High Side Low Input'. Symptoms include hard starting in cold weather and white smoke.
• Volkswagen Jetta, Golf (MK4) (1999-2005) — Translates to 'Engine Control Module (ECM) 2 Defective', pointing directly to a failure of the main computer.
• BMW 3-Series, 5-Series (E46/E39) (1998-2005) — Manufacturer-specific code for 'Ignition Coil 5 - Ionization Current Malfunction', indicating a problem with a specific ignition coil.

Manufacturer-Specific Notes

• Chrysler/Dodge/Jeep: The voltage regulator is built into the PCM. A short circuit in the charging system or ASD circuit sends a voltage spike that destroys the PCM. A melting C3 connector at the PCM is a classic sign of this failure mode.
• Ford: P1389 means 'Variable Cam Timing (VCT) Solenoid B Circuit Malfunction' on gas engines or 'Glow Plug Circuit High Side Low Input' on diesels. It has nothing to do with an ASD relay.
• General: Refurbished PCMs frequently arrive faulty or fail quickly. Verify the integrity of the wiring before and after installing a replacement PCM to avoid destroying the new unit.

Real Owner Stories

2001 Dodge Ram 1500 5.9L with Intermittent No-Start

Truck intermittently cranked but would not start. After waiting 20 minutes, it started and ran fine, but with the Check Engine Light on for P1389.

What they tried:

1. Swapped the ASD relay with the wiper relay.
2. Inspected the PCM and found it was getting hot and melting the connector around pin 12.

Outcome: The root cause was a fried PCM that was also destroying replacement PCMs. This points to an underlying wiring short that must be fixed before replacing the computer.

Lesson: An intermittent no-start that resolves itself after a cool-down period indicates a failing PCM. If you find a melted PCM connector, you must fix the wiring short that caused it, or it will destroy the replacement PCM.

2000 Jeep Cherokee XJ with Crank-No-Start After Being Parked

Vehicle was parked for a month. It cranked but would not fire. It had fuel pressure but no spark, and code P1389 was present.

What they tried:

1. Replaced the Crankshaft Position Sensor (CPS).
2. Swapped the ASD relay and checked the ASD fuse.

Outcome: The owner traced the fault to a broken plastic clip in the fuse box (PDC) that allowed the ASD relay's female connector to become loose, breaking the circuit.

Lesson: Do not just swap relays; inspect the socket itself for damage. A physically broken relay socket or terminal creates the exact same symptoms as a bad relay.

1999 Dodge Ram 5.9L with P1389 After Alternator Replacement

The owner replaced a failed alternator. Three miles later, the charging system failed again, the Check Engine Light came on with P1389, and the truck would not restart.

What they tried:

1. Verified the ASD relay was good and getting power.
2. Cleaned all ground connections and the PCM connectors.

Outcome: The problem was a faulty Crankshaft Position Sensor. The failing alternator created voltage spikes that damaged the sensitive crank sensor.

Lesson: If P1389 appears immediately after an electrical repair (like an alternator), the events are related. Always diagnose related codes (like the crank sensor) before condemning the PCM.

How to Prevent This Code From Triggering

• Apply Dielectric Grease to Relay Terminals (Every 3-5 years or when replacing a relay.) — Dielectric grease seals electrical connections from moisture and salt. Applying a thin coat to the relay blades prevents corrosion, a primary cause of high resistance that triggers P1389.
• Inspect and Clean Main Ground Straps (Every 30,000 miles or annually.) — Corroded ground straps create voltage drops that cause the PCM to misinterpret sensor data or behave erratically, leading to clicking relays or false codes.
• Protect Wiring from Rodents (If parking outdoors or for long periods.) — Rodents chew on soy-based wire insulation. Wrap critical wiring harnesses in capsaicin-laced anti-rodent tape or install an ultrasonic repellent device in the engine bay.

Frequently Asked Questions

What is an ASD relay and what does it do?

The Auto Shutdown (ASD) relay is a master power switch that the engine computer (PCM) uses to control power to critical components like the ignition coils, fuel injectors, and fuel pump. It is a safety device designed to shut off fuel and spark when the engine is not running.

Can I just replace the ASD relay to fix P1389?

Replacing the ASD relay is an excellent first step because it is inexpensive and a very common cause. You can swap it with your horn relay to test it. If that fails, the problem lies in the wiring or the PCM.

Why won't my car start with code P1389?

Your car will not start because the ASD relay cuts power to the ignition system and fuel injectors. Without electricity to create a spark and deliver fuel, the engine only cranks.

Is it dangerous to drive with a P1389 code?

Yes, it is extremely dangerous. If the code is intermittent, the ASD relay shuts off randomly, causing the engine to stall while driving. This leads to a complete loss of power steering and power brakes.

My mechanic says I need a new PCM. Is that common for this code?

Yes, on many Dodge, Jeep, and Chrysler vehicles, a faulty PCM is a known cause for P1389. A short in the wiring damages the internal circuits of the PCM. However, all wiring, fuses, and the relay must be thoroughly tested before condemning the computer.

What are common misdiagnosis mistakes for P1389?

A major pitfall is replacing the PCM without confirming the wiring is intact. Wires chafe and break near the back of the engine or at the PCM connector, which is a much cheaper fix. Another mistake is ignoring crankshaft sensor codes (P0320), which actually cause the P1389.

I swapped the ASD relay and the car still won't start. What's next?

Use a multimeter to verify power at the relay socket and ensure the PCM sends a ground signal during cranking. If those are present, test the continuity of the output wire from the relay to the PCM. This methodical process isolates the exact fault location.

What does 'No ASD Relay Output Voltage at PCM' actually mean?

It means the Powertrain Control Module (PCM) commanded the ASD relay 'on', but detected no voltage on the confirmation wire. The PCM uses a 'sense' circuit to verify its commands. When this confirmation fails, it triggers P1389 and cuts engine power.

Key Takeaways

• Code P1389 primarily strikes 1998-2004 Chrysler, Dodge, and Jeep vehicles, triggering an immediate crank-no-start or sudden highway stalling condition.
• Fix this code 50% of the time for under $20 by swapping the ASD relay with the identical horn relay or replacing a blown 30A fuse.
• If a new relay fails to start the engine, test the continuity of the ASD output sense wire before spending $500+ on a replacement Powertrain Control Module (PCM).
• Never drive a vehicle with an intermittent P1389 code, as the engine will shut off without warning and instantly disable your power steering and brakes.
• Verify your manufacturer's specific definition, as P1389 means 'Glow Plug Circuit Low' on Ford diesels and 'ECM Defective' on Volkswagens.