TCM Power Relay Control Circuit High
The P0887 code indicates that the Transmission Control Module (TCM) has detected a high voltage condition in the power relay control circuit. This circuit supplies power to the TCM and related transmission components. A high voltage reading can be caused by a faulty relay, wiring issues, or a short to voltage. This can lead to erratic transmission behavior or failure to shift.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Transmission shifting erratically or stuck in gear
- Transmission may not shift at all
- Reduced fuel economy
2. Most Common Causes
- Faulty TCM power relay
- Short to voltage in the relay control circuit
- Damaged wiring or connectors in the relay circuit
- Corroded or loose relay socket terminals
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all codes and freeze frame data.
Step 2: Inspect the TCM power relay and its socket for corrosion or damage.
Step 3: Test the relay control circuit for voltage with a multimeter; compare to manufacturer specs.
Step 4: Check wiring and connectors for shorts, opens, or damage; repair as needed.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The transmission may fail to shift properly, leading to loss of vehicle control or transmission damage.
How much does it cost to fix?▼
Typically $50-$150 for relay replacement or wiring repair, but costs can vary based on labor rates and parts.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.