TCM Power Relay Sense Circuit Range/Performance
The P0889 code indicates that the Transmission Control Module (TCM) has detected an unexpected voltage or resistance in the power relay sense circuit. This circuit monitors the voltage supplied to the TCM from the transmission control relay. When the voltage is out of the expected range or the relay does not operate correctly, the code is set. This can lead to erratic transmission behavior or no start conditions.
01. Most Common Causes
- Faulty transmission control relay
- Blown fuse or wiring issues in the relay circuit
- Corroded or loose connectors at the TCM or relay
- Failed TCM (less common)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Transmission shifting erratically or stuck in gear
- Vehicle may not start or stall
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for other codes and note freeze frame data.
Step 2: Inspect the transmission control relay and its fuse; test relay operation.
Step 3: Check wiring and connectors for damage, corrosion, or looseness.
Step 4: Measure voltage at the TCM power relay sense pin; compare to specifications.
Step 5: If all else is fine, test the TCM for internal faults.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended as the transmission may fail to shift properly or the vehicle may stall, posing a safety risk.
How much does it cost to fix?▼
Typically $50-$150 for relay or fuse replacement; more if wiring repair or TCM replacement is needed.