Overdrive with a mind of its own
 

O/D is turning off an on by itself. Hoping that someone has experienced something like this and may have pointers...

Details:

Car: 2006 Sentra 1.8S (B15) with auto (obviously, but not sure which trans)
Miles: 170k

Symptom:

O/D (light) flips on or off occasionally (not every day). Sometimes won't respond to O/D button for a few minutes. O/D is actually being turned on and off, not just the light. It may switch on and off a dozen times, randomly, for 5-10 minutes and then everything goes back to normal.

I don't want to ignore it because of the potential for massive transmission wear from the extra shifting.

Troubleshooting:

1) TCM diagnostic mode: No faults
2) OBD: no faults
3) Pulled apart shifter, no wire damage, switch works.
4) Disconnected switch harness (by cig lighter), problem still happened (it's not the switch).
5) Traced wire to Combination Meter pin 22, continuity good, unaffected by moving wires around, does not go to ground when moving.

My next steps:

1) Cut the wire at Combination Meter (or remove from harness) to see if it still happens
2) Replace Combination Meter.

Anyone think I'm being an idiot?


Many thanks.

For the record, the Combination Meter (instrument cluster) was the cause. Bought a used one on Ebay, reprogrammed the odometer to match my car, no more overdrive issues. My write-up on odometer reprogramming:Odometer Reprogramming - Nissan Sentra - Akom's Tech Ruminations

If I had to guess why this happened, I'd say I was using the O/D switch too much, so keep that in mind.