TCM Power Relay Control Circuit/Open
The P0885 code indicates that the Transmission Control Module (TCM) has detected an open or malfunction in the power relay control circuit. This relay supplies voltage to the TCM, and when the circuit is open, the TCM may lose power or operate intermittently, leading to transmission performance issues.
1. Symptoms You Will Notice
- Transmission shifting erratically or stuck in gear
- Check Engine Light illuminated
- Transmission may go into limp mode
- No start condition if TCM loses power
2. Most Common Causes
- Blown fuse in the TCM power circuit
- Faulty TCM power relay
- Open or shorted wiring in the relay control circuit
- Corroded or loose relay socket connections
3. Step-by-Step Diagnosis
Step 1: Check for blown fuses related to the TCM power circuit and replace if necessary.
Step 2: Locate the TCM power relay and test it for proper operation using a multimeter.
Step 3: Inspect wiring and connectors for damage, corrosion, or loose connections.
Step 4: Verify voltage at the TCM power input pin with the relay energized.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The transmission may fail to shift properly or go into limp mode, which can cause unsafe driving conditions.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on whether a relay or fuse needs replacement.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.