I mentioned this in another thread. HeyYou posted a pic showing where the O/D light is. I checked a little while ago and I have no OD light at all, even at KOEO bulb check when you first turn the key. While driving if I hit the O/D switch on the gear selector, I don't really notice any difference in RPM/driving condition at all.

I don't drive the truck much, so I figure I may as well do some work on it while it's sitting. It's mostly for hauling materials for the house.

 

You need to be over 45 mph before the od will kick in. I believe the only time the od light comes on is when the od is off.

 

It should still come on during the bulb check, shouldn't it? When I hit the O/D off button on the gear select I don't notice any difference in RPM or driving, be it 45 or 70MPH.

 

You can test the switch. All it does is send a voltage signal to the PCM, to tell it you don't want overdrive. PCM takes it from there. (dropping to third, and turning on the lite.)

 

Do you know of a good quick n dirty test for the switch off the top of your head? It's obv a momentary switch. Maybe the scan tool has a switch status? I noticed it does for my speed control switches in my caravan. I haven't hooked it up to the truck yet.

 

That's interesting.... If it can test the cruise switches, it would make sense (yeah, I know.....) that you could test to O/D switch as well.

Either that, or just backprobe the output wire at the pcm.

Oops, looking at the wiring diagram.... the switch grounds a circuit..... check and see if you are getting any voltage on the Black/Light Green wire at Ground 200. (down at the base of the steering column.)

 

I'll try and give it a poke this weekend. Taking the truck about 10 miles down the road to snag a chicken coop. Have I mentioned how rad having the 8ft bed is?