P0890high severityPowertrain
TCM Power Relay Sense Circuit Signal Stuck On
on 2007 Mercedes-Benz S65 AMG 6.0L V12 BiTurbo M275 · RWD
What this code means
The transmission control module sees the power relay sense signal stuck in the on state. The relay is not de-energizing when commanded off.
Symptoms
- Transmission warning light on
- Relay stays powered after key off
- Shifting problems
Common causes
- Stuck TCM power relay
- Wiring short to power
- Corroded relay contacts
- Faulty transmission control module
Diagnostic steps
- Scan for related transmission codes
- Test relay for stuck contacts
- Measure sense voltage during key off
- Inspect wiring for short to power
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