TCM Power Relay Control Circuit Low
The P0886 code indicates that the Transmission Control Module (TCM) has detected a low voltage condition in the power relay control circuit. This circuit supplies power to the TCM and related transmission components. A low voltage reading suggests a fault in the relay, wiring, or the TCM itself, which can lead to transmission performance issues or failure to shift.
01. Most Common Causes
- Faulty TCM power relay
- Open or shorted wiring in the relay control circuit
- Blown fuse or poor electrical connection
- Failed TCM
02. Symptoms You Will Notice
- Transmission stuck in limp mode or fails to shift
- Check Engine Light illuminated
- Erratic shifting or transmission slipping
- No start condition (if TCM controls starter relay)
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and check freeze frame data.
Step 2: Inspect the TCM power relay and fuse; test for voltage at the relay coil and switch terminals.
Step 3: Check wiring and connectors for damage, corrosion, or loose connections.
Step 4: If relay and wiring are okay, test the TCM for proper ground and power supply; replace TCM if necessary.
04. Commonly Affected Makes
05. 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 and potential damage to the transmission.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on whether the issue is a relay, wiring repair, or fuse replacement. TCM replacement can cost significantly more.