Hello guys,
I just registered on this site to become a memeber. I am 600 miles from home and my overdrive just quit working. I have a 92 cummins 2 wheel drive with 79,000 miles on it.
I have done the following:
trans fluid is full
the button on my dash to turn the overdrive off wont light up.
the fuse that controls the overdrive module is good.
** Is there a relay or module taht I can check?
My cell is 214-315-6070 My name is Todd
Thanks!!!

 

Check the wires that run to the speed sensor. See if has a bare spot right where the shifter rod comes down for the auto tranny.

 

See if there is a group of wires coming on on the driver's side about the middle of the trans. Unplug them, carefully tweak the pins and reinstall. If those pins lose contact the OD won't work.

 

i had the same thing happen when i had my 92,
the throttle position sensor is bad

 

I don't know if this will apply to you (TPS??) but on my '95 when the TPS sensor finally died totally I had no OD and no lockup. I don't know if its the same system on the '92 but maybe someone else can confirm.

 

engine speed sensor and crankshaft sensor are thesame part located beneath fan blade and above harmonic balancer at about 11 o'clock position. If it is bad you will will also lose tach, alt, a/c and overdrive. if the tach reads 0 this tells the comp that the engine is not running and it wont turn on these functions. the tps is located at the front of the motor on the drivers side- you can take it off and clean it this will work sometimes. check with a cummins dealer the tps is $166 and the ess or css is around $75.

 

Not sure if the gear drive is affected/controlled the same as Lock up , Overdrive & cruse control , but if the brake sw. is bad or out of adjustment they will not work in a stock truck , push peddle with one hand and pull sw button out with other hand , do not lift peddle , as this will set adjustment too high .

 

OK, here is an update...my buddy is the one with the truck and he has been chasing his tail all day since he has no tools, the kids are with him, etc. He did buy a new TPS but it made no difference. He has checked all the wiring for any cuts, etc. but says it all looks good. Reseated the plug on the tranny as advised above.
One thing he did tell me is that he is only getting 12.5 volts out of the alternator (took it off at the auto parts store but it tested good). He says the needle on the voltmeter guage on the dash is definately lower than usual. Also, the cruise no longer works or the a/c! Its like he has most of his electrical accesories!

Now looking at "tonystruck"'s post above, it sounds like exactly what he has described. Possible bad ESS or CSS???

I called my friend to let him now, he is calling the parts store right now to see if that have one in stock....will update asap.

Thanks for the help guys!