Today I had my Rancho RS9000xl 4x shocks installed on my truck, tonight at least 3 times, the OD light came on, solid. It wasn't flashing, it just came on- each time that I noticed it was on as we were exiting a parking lot. I was able to simply 'turn the light off' by pushing the OD toggle on the shifter.

As well, I was slightly low (but still within spec) on coolant from an intake changeover a few weeks ago that required changing the line- I added the RP coolant additive today...

When it was in the shop this AM for the shocks, I went ahead and had them change the differential fluid to the Royal Purple w/ LS additive. 3 qts was what was added- is it possible there's not enough- and it's causing a false 'load' - I'm not sure if there IS an OD sensor or not that turns the OD off when the trans is working too hard...

Recently, I should note, I also changed my O2 sensors and it took some tugging on the upstream plug on the passenger side; granted, it's probably not related- but worth mentioning.


Thoughts?

 

Did it again one time today; it wasn't on when I cranked the engine- but the second I went from reverse to drive quickly, (while at a stop, though) it turned on right when I applied the gas. I couldn't replicate it; and always seems to happen right from a cold start and involved shifting and/or hitting a bump.


I'm curious if the Royal Purple additive is enough, or if I just need to add more to the differential.

 

I don't want it to sound insulting but if I remember right aren't those OD off buttons right on the shifter? If you're like me you keep your hand on the shifter most of the time, habit from driving a 5 speed i guess.. Is there any way when you're shifting or hitting bumps you're accidentally hitting the OD off button with your thumb? If not, Usually when the OD off light comes on by itself it's because there is a transmission fault. If you have your truck scanned for transmission codes there might be some stored from whatever is going on.

 

Nope, not hitting the shifter at all, LOL! But I had the same thought, I've driven it for a few months now and never once hit it--- but today I made a conscious effort to avoid manhandling that button, in case it WAS just a coincidence.

As for the light, usually when it throws a trans code it flashes--- it's not flashing... I'll go out there with the SCT now and check it for any codes. It's almost certainly related to the differential change, as it happened RIGHT after this change.


*update;
just checked, no DTC codes logged.

 

Alright, just had to check first. You'd be surprised how often we see overdrive lights in the dealership from people hitting the button.. I don't believe there is an automatic overdrive cancel feature. My opinion is that it's an electrical issue with the overdrive switch. Try to move the shifter head around, twist it and shake it and stuff and see if you can get the light to come on without hitting the button.

 

Do you happen to know if that circuit runs anywhere near the passenger side upstream O2 sensor? I yanked the snot out of that connector to get it out of there... If anything went it was there- Unfortunately up behind the cat has zero visibility.

 

No, the wire runs from the switch to the pcm and the instrument cluster. The wires will break at points where they move or pins can come loose in connectors near there. Whether you have the floor shifter or the column shifter try to move the shifter around or better yet get to the harness and try and wiggle and tug it. I say that because you said the light comes on when accelerating hard and turning or shifting fast and that's when the harness and connectors will be stressed more.

 

Went out and checked the differential, the fluid was a 'little' low- so I added some more RP, dipping my finger in i felt it just below the hole now.

As well, I verified all of the harness connections and felt something 'click' as if it was snapping back 'in'. This morning I gave it hell on the way to work and the OD light didn't come on once.

Thanks for the help.

 

No problem. Someone might have had the connector off before and didn't quite get it back on, or I've even seen them from factory and maybe it just finally got loose enough to give you an intermittent light. I hope it's cleared up for you though.