P0885 — TCM Power Relay Control Circuit/Open #

Note: The code label may differ depending on the vehicle manufacturer.

• P0885 — Transmission Control Module Power Relay Control Circuit/Open (Generic/Chrysler)
• P0885 — TCM Power Relay Control Circuit Open (Ford)
• P0885 — TCM Power Relay Control Circuit/Open (GM/Chevrolet)

Summary of DTC P0885 #

The diagnostic trouble code P0885 indicates an issue within the Transmission Control Module (TCM) Power Relay Control Circuit. The TCM is the electronic brain that manages your vehicle’s automatic transmission functions for optimal performance and efficiency. The power relay is an electronically controlled switch that supplies power to the TCM whenever necessary. When the Engine Control Module (ECM) or Powertrain Control Module (PCM) detects an open or malfunction in the relay control circuit—meaning an interruption or break in the circuit—it triggers P0885. This can lead to communication problems between the TCM and other critical systems, potentially impacting drivability and shifting quality. The code’s presence should prompt timely investigation to avoid further complications.

Common Symptoms for DTC P0885 #

When P0885 appears, your vehicle might display several noticeable and less-obvious symptoms. Some drivers experience abrupt shifting, while others might only see the check engine light illuminated. Ignoring these signs is like turning up the radio to drown out a strange noise—problems won’t go away, and may worsen. Here’s what you’re likely to notice:

• Check Engine Light illuminated
• Transmission stuck in limp mode (only one or two gears available)
• Harsh or erratic shifting
• Delayed engagement when shifting into drive or reverse
• No start condition (rare, but possible if TCM power is lost)

Probable Causes for DTC P0885 #

The causes behind P0885 range from simple electrical issues to more complex module failures. Think of the circuit as a postal system—if any part of the delivery route breaks down, the message (power) won’t reach its destination. Here are the most common culprits, ranked by frequency:

1. Faulty or failed TCM power relay
2. Open or damaged wiring in the relay control circuit (e.g., broken wires, poor connections)
3. Corroded, loose, or damaged relay terminals
4. Defective Transmission Control Module (TCM)
5. Blown fuse in the TCM circuit
6. Issues with the Powertrain Control Module (PCM) or Engine Control Module (ECM)

Step-by-Step Diagnosis for DTC P0885 #

Properly diagnosing P0885 requires a systematic approach—like following a treasure map, each clue leading you closer to the root cause. Rushing through or skipping steps can result in wasted time and unnecessary parts replacement. Here’s a proven sequence:

• Scan for additional trouble codes that may offer related clues.
• Visually inspect TCM power relay, related wiring, and connectors for damage, corrosion, or loose connections.
• Test the TCM power relay per the OEM (Original Equipment Manufacturer) procedure with a multimeter; replace if faulty.
• Check for blown fuses in the TCM circuit and replace as needed.
• Use a wiring diagram to check continuity and voltage in the relay control circuit; repair any open or damaged wires.
• Consult OEM technical service bulletins (TSBs) for known issues or updated diagnostic steps.
• If all else checks out, test the TCM or have it evaluated by a professional, as module failure is less common but possible.

Possible Repairs for DTC P0885 #

Depending on what the diagnostic process uncovers, repairs for P0885 can be straightforward or involve more advanced work. Each repair targets a specific weak link in the chain, restoring reliable communication and power delivery to the TCM:

• Replace a faulty TCM power relay
• Repair or replace damaged wiring or connectors in the relay control circuit
• Clean or replace corroded relay terminals
• Replace blown fuses in the TCM power circuit
• Replace or reprogram the TCM if it’s confirmed to have failed
• Address any issues with the PCM/ECM as indicated by further diagnostics

Is It Safe to Drive With Code P0885? #

Short answer: No, or only with great caution. While some vehicles may remain drivable with P0885, transmission performance is often compromised—think of it as running a marathon with a sprained ankle. Limp mode may limit your speed and gear selection, increasing the risk of sudden loss of power or further transmission damage. If you see this code, it’s wise to minimize driving and arrange for diagnostics and repairs as soon as possible.

Vehicles Most Commonly Affected by DTC P0885 #

While P0885 is a generic OBD-II code, it’s most frequently reported on certain makes and models—often due to design similarities or relay placement. If your vehicle is listed below, stay especially alert for transmission issues:

• Chrysler, Dodge, and Jeep vehicles (multiple model years)
• Ford trucks and SUVs (various models)
• General Motors (Chevrolet, GMC, Buick) cars and trucks
• Some Mitsubishi and Hyundai models

Common Mistakes and Best Practices for DTC P0885 #

Misdiagnosis is a common pitfall with P0885, especially when skipping systematic troubleshooting. It’s easy to swap out the relay and assume the problem will vanish, only to discover that underlying wiring or module issues persist. Here’s how to avoid common errors:

• Don’t replace the TCM or relay without confirming actual failure.
• Avoid overlooking simple issues like blown fuses or corroded connectors.
• Always use the correct wiring diagram for your vehicle’s year and model.
• Document all steps taken and parts checked for future reference.
• Double-check for related codes that could point to a root cause elsewhere.

Fast FAQ for DTC P0885 #

Got questions about P0885? Here are quick answers to the most common concerns:

• Q: Can a dead battery trigger P0885?
  A: Yes, a severely discharged or disconnected battery can temporarily interrupt power to the TCM, potentially setting the code. However, if the issue persists after restoring battery power, further diagnosis is required.
• Q: Do I need special tools to fix P0885?
  A: Basic tools like a digital multimeter, wiring diagram, and scan tool are usually sufficient for diagnosis. However, programming or replacing the TCM often requires OEM-level scan tools and software.