does any one have the electrical digaram tor this truck or does it eaven exist ?
Trying to figure out if i`m losing ground or + to spedo and overdrive, & cruse , seems like when one works they all work and when one doesnt they all dont. where is the common connection there????????
Trying to use logic to track down the problem.

tried hooking up pot,in place of TPS didnt do anything,cleaned all connections on trans and on Tps
in 40 mile trip spedo worked iradically for 6 mi and OD hooked up 6 or so times , Have to be losing ground or + for this to happen .
today i`m going to run new ground from motor to cowell,already replaced ground from engine to battery.

This thing is driving me nuts!!!!!!!!!!!!!!!
NEED TO GET IT FIXED ,HAVE TO RUN 7 OR 8 HRS EACH WAY WITH CAR TRAYLOR TO PICK UP A CAR , CANT IMAGINE DOING THAT WITH NO OD ,OR SPEDO !!!!!!!!!
Claude

 

OK i added a ground wire from cowell to engine , re cleaned wire connections!!!!!!
driving 20 mi showes 11 on spedo now so made some progress and OD worked off and on . WHAT AM I MISSING ????????????????????????????
CLAUDE

 

Have you replaced the speed sensor?

 

Yes , in the last 2 yrs 2 times , spedo is working more all the time ,since ive been cleaning connections and moving wires eaven under dash.

 

Sorry I didn't see this earlier. You have a speed sensor problem, that is the only thing that will cause all your symptoms. It may not be electrical, though. It's pretty common for the adapter between the speed sensor and the trans to strip out. Check that out thoroughly.

The wiring is pretty simple, is yours a 2wd or a 4wd?

 

2 wheel .
? should end of sensor be able to turn ?
May sound goofy but seems to be some connection between spedo running properly and OD working.

When spedo is floping around like a fish out of watter Od jumps in and out ------ some times locking in longer than others, however when spedo is laying there like dead fish ,
OD doesnt eaven try to work!!!!!!!!!!!!!!!

Dont know if ther is a connection but cruse doesn`t work eather.
10:00 i`m still working on it , wanted to get outof here some time tonight ,from up here to Indinapolis is about 7 hrs and i`m going about 40 mi farther south to Blumington,pulling car trailor to pick up car to bring back.

This week has been a real panick ,trying to get this figured out.
Well changed my mind not taking off until Sat morning ,need to get these gliches worked out!

 

Probably too late to help, but here goes. The computer runs the OD and the cruise, and it needs the signal from the speed sensor to do it. The speedo also runs off the speed sensor, but does not need the computer. You have a sensor or wiring problem. If you pull the sensor off the trans you should be able to spin it easily with your fingers. Most trucks have an adapter between the sensor and the trans, and it is pretty common for that to get stripped out and cause the problems you are seeing, so check the mechanical end of it closely.

A 2wd auto has 3 wires going to the sensor. Tan/yellow should be 8 volt supply from the computer (pin 7 on the big connector), black/light blue should be a good ground, and white/orange is signal to the speedo and the computer (pin 47).

 

OK, now i`m totally cunfused they told me 3 wire plug on side of tranny was d/n/r sensor , and the two wire above it was to tps. this did make me scratch my head because tps has 3 wires , although 3 wire could go some where else in harnis.
Two late for this road trip ,However OLD DOG handled it like the true champ he is, about 475 mi and under 35 gal of fuel hauling car trailor and about the same loaded on way back.
THis being said i stil need to get this sorted out.
This is why ive been trying to find wire in diagram so i could trace down problem.
you say end of speed sensor should turn freely ,how freely, mine turns like a bolt that is almost to the end of being finger tight.
WHEN SPEDO DROPES OUT, OD MAKES NO EFFORT TO ENGAGE/ONLY ENGAGES OR MAKES EFFORT WHEN SPEDO IS FLOPING AROUND LIKE FISH OUT OF WATTER.
Thanks
Claude

 

OD won't work unless there is a constant clean signal from the speed sensor. Period. Your speedo flopping around could be the speedo head or a bad signal. Speedo can work and be steady and the OD will still drop in and out because the signal is not steady enough for the SBEC but it is for the speedo.

Yes, there should be some resistance to turning the speed sensor, about what you described. The next thing you might check is whether the gear in the trans is good and the holder is lined up correctly. I have seen the gear go bad and not turn consistently. Pull the speedometer piece out of the trans and verify you have a good gear and that the end of the speedo gear has not gotten rounded and is slipping. It sounds like you have problems at the trans with the speed sensor drive.

If that checks out good start by checking your fusible links. The power to the trans for the OD is run from those. The 2 wire flat connector on the top side is the OD connector. The neutral safety switch is the round one closer to the pan rail. TPS has three wires: power, ground, and signal. The signal wire tells the SBEC when to ground the wire from the OD solenoid to apply OD. Trans only needs 2 wires, one for power source and one for ground.

 

checking and working on it
Thanks <ill let you know here how i come out.
CAME BACK IN SIDE TO WARM UP HANDS,(MAN ITS ONLY 16 DEGREES OUT THERE THIS MORNING!
Thanks
Claude