fitzydog

Not sure. 94 47rh dually. New trans within last 10k miles? Aaron

infidel

Only thing I can think of that would cause both problems at the same time is a bad brake light switch.
Brake lights can still work fine as there are three sets of contacts on the switch.
New one is $11 at Napa.

fitzydog

I appreciate the reply. I work at advance auto and replaced the switch about 6 months ago but who knows it may be bad? I was thinking the sensor in the overdrive but that is the Vehicle speed sensor right? The speedometer and odometer are in perfect working condition. Thanks for the reply.

thegoat86

Really? A bad brake light switch? Is this really a cause of no OD and lost cruise control? I have a 91.5 with identicle problems. I ran a jumper to the control module to force OD, but am not getting lock up. Lost two trannys to the problem because I cant find the originator problem. Fitzydog, did you fix the problem?

fitzydog

Thanks for asking sorry been away for a while. I did adjust the brake light switch and wha lah. I used the method of pulling up the brake pedal while driving and the overdrive kicked in and cruise right away. Thanks so much.

thegoat86

can the same apply for a 91?

Lil Dog

If you don't have a tach, the engine speed sensor would be the next culprit to check on a 91..

thegoat86

where would that engine speed sensor be located? Also I am hearing the scraping from my steering column which I suspect is the cruise spring thing. Would this also cause the OD to not work? My speed sensor on my trans works good. No pulsing or anything wierd.

96cumin

my 96 12v does the same thing no O/D or cruise.. how do i fix it? and wen i push O/D off button it seems like the tranny is in a higher gear for the speed im going. also wen i hook up trailer lights dont seem to work quit right, would any of this have anything to do with brake light switch? any other ideas would be great thanks!

Lil Dog

The ESS is located at the front of the engine, up near the water pump facing the balancer. Sometimes the sensor goes bad or the wires rub through along the way .

96,

If the brake switch is at all out of adjustment, it will cause the OD/cruise not to function. Basically it thinks you are hitting the brakes and unlocks the torque converter. Does yours have the Tow package or did you add your own harness?

96cumin

how do you adjust the brake light switch? also the brake light comes on. it has a tow package and wen i hook up my trailor the trailor lights and lights on truck go really dim and other weird things happen and wen i hook it up to the boat the running lights come on with brake lights really weird.

96cumin

i also have trailor braks, i never had any of these problems about 6 months ago

Lil Dog

Sounds like a bad ground connection to your trailer. I would check the plug for a broken wire and break out the volt meter to check for proper output to each pin on the hitch plug. Then I would check the plug on the trailer for the same or corroded wires.

Now as far as the brake switch, there was a quick writeup on that on here for setting the clearance on the brake switch.. Something about turning the pin on the switch to let it out and then installing it. If its just worn out, its pretty cheap to replace. IIRC the switch has 2 circuits in it for the PCM and brake lites on separate wires.

thegoat86

OK, wouldnt the speed sensor code out? I got the obd1 cable and hooked up my scan tool. Got no codes, and it shows the rpm. So I am assuming it works ok. Anything else cause loss of od and cruise at same time?

Lil Dog

Well if you have rpm then that takes out the ESS.. Hmm.. All fuses are good? I will have to do some digging. Search the Gen1 forum too..