TCM Power Relay Sense Circuit
What it means
P0888 refers to the transmission control module's power-relay sense circuit — the feedback line the TCM uses to confirm its relay is supplying power. When that sense signal isn't what the TCM expects, it can't be sure it has stable power, which may leave the transmission unable to shift normally or stuck in a limp-mode gear. Note that some raw databases mislabel this as "Traction Control Module"; the standard defines it as the Transmission Control Module. The engine itself still starts and runs.
Can I keep driving? Driveable, but if the TCM loses power the transmission may be stuck in limp mode or one gear; repair it promptly.
Common symptoms
What you'll notice
- Check-engine light on
- Transmission not shifting properly
- Stuck in one gear / limp mode
- Reduced acceleration
Common causes
Most likely first
- Failed TCM power relayLikely
- Wiring fault in the relay sense circuitCommon
- Loose or corroded connector or groundCommon
- Faulty transmission control moduleLess often
How to diagnose & fix
Work through it in order
- Check the TCM power relay and its fuse.
- Verify power and ground at the TCM relay sense circuit.
- Inspect wiring and connectors for corrosion or looseness.
- Replace the relay if it fails to switch cleanly; test the TCM last.
- Clear the code and retest.
FAQ
Quick answers
Is it safe to drive with P0888?+
Can I just clear P0888?+
Related codes
Often seen with P0888
Read & clear P0888 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.