Lost Overdrive

[CMichel]

I have a 94 4x4 that I had the transmission rebuilt 1 year ago. At the time I had it rebuilt I had them put in a DTT vb/tc. Last week I adjusted the bands and after that I haven't had overdrive, everything else about the transmission works fine. I'd called Bill K. and he told me how to check for electrical problems, and if I understood how to do the check, the electrical was ok. Bill is currently moveing and is hard to get on the phone. My question is, do you have any ideas what could be wrong, and would anyone recommend a transmission shop in the south central Missouri area?



Thanks, Clint

 

[inarush76]

OD MIA

Clint, what checks did you make? It is possible that if the trans was working fine before the service and lock up still works that the signal wire to the OD solenoid got caught between the filter and valve body and got damaged. Or if neither lockup or OD works the supply wire got pinched and blew a fuse. The center wire on the case connector is 12v feed, the front and rear wires are OD and TCC. Using a voltmeter or some LED's you can drive it to check for ground signals to the solenoids. The speed sensors on those trucks are infamous for sudden departure from the functional as well. Let me know what and how you checked it and I'll try to help.

James Northum

DTT dealer/installer/builder

near Dallas,TX

 

[HoleshotHolset]

James is right... .

My truck will every so often come out of OD while going down the highway... ... . Yeah, talk about scaring the crap out of you! The problem happens so seldom that I haven't done anything about it. Some folks have even tried to trace the problem to the OD lockout switch/it's wiring... . no dice.



Another possibility is the temp sensor/or its wiring..... if you want to eliminate the sensor from the equation..... wire in 7. 5k-Ohms of resistance between the two wires that go to the sensor. I cut up my OEM sensor and soldered the resistors to the little wires inside the sensor, then gooped it up with RTV and a little plastic cap for a watertight seal. So far, so good.



Now I have OD all the time... . even when it's cold... . which I didn't have before. Darn engineers at Chrysler thought they'd be cool (pun intended) and disallow OD at temperatures below 60°F to prevent damage to the OD section from improper lubrication.



Hope this helps in addition to James' comments.....



Matt

 

[CMichel]

James,



I attached a wire to the front (brown) wire and ran it to a switch, from the switch to chassis ground, and flipped it on at 55 mph. I understood Bill K. to say this would by-pass the electronics. Nothing changed when i did that. Could some debris have gotten knocked loose when i tightened the bands and ended up in the valve body?



Thanks for your reply,

Clint

 

[Roger rodbolt]

Originally posted by CMichel

I have a 94 4x4 that I had the transmission rebuilt 1 year ago. At the time I had it rebuilt I had them put in a DTT vb/tc. Last week I adjusted the bands and after that I haven't had overdrive, everything else about the transmission works fine. I'd called Bill K. and he told me how to check for electrical problems, and if I understood how to do the check, the electrical was ok. Bill is currently moveing and is hard to get on the phone. My question is, do you have any ideas what could be wrong, and would anyone recommend a transmission shop in the south central Missouri area?



Thanks, Clint

Clint,

I can recommend two shops in cental Missouri but not south central. I've seen problems steming from the front band being too tight after adjustment, it's easy to let the adjustment thread in while securing the locknut. This should affect more then just overdrive though... ... If I can be of assitance let me know. LC in the Show Me state.

 

[inarush76]

OD

Clint, do you have 12v to the center wire at the trans? If so, try unplugging the trans and connect an ohmmeter across the center and front pins and then the center and rear pins. The ohms should be about the same. Also after you have confirmed 12v, you can, with key on-engine off, trans plug connected, have someone flip the switch you installed while you listen for a click at the pan from the solenoid. I believe solenoids should ohm about 31 ohms. Did you pull the pan and check the solenoid wires under the filter? HTH

James

 

[CMichel]

James, I have 12v at the center wire. I have 36 ohms at the pins. The wires inside the pan look good.



Roger, I was careful not to let the adjusting screw go in when securing the lock nut. Later I even backed it out a turn and drove it for several miles to insure the front band wasn't to tight.



Thanks, Clint

 

[CMichel]

I ran some more test today. When i flip the switch between the 12v and front wire i don't here the solenoid click.

With the engine on i have 13v at the front wire till i get to 40 mph then it drops to 1v, the rear wire drops to . 2v.



I also checked my line pressures. The middle line is 70 psi at idle in drive and goes on up to 100psi @ 60 mph or about 2200 rpm.

The governor port is 0 till about 25 mph then it jumps to 50 psi, at that point the psi goes up relative to speed and tops out at 100 psi at 60 mph.



I also had an extra tps, which the previous owner had left in the truck. It appeared to be new, but there was no change from the tps that was in to begin with.



Thanks for any help you can give, Clint

 

[Strick-9]

Does the torque converter lock when you turn off OD and cruise?



How is the rest of the shifting? What rpm are the shifts (light throttle/WOT)

The governor pressure hanging at 0psi until 25mph should create some shifting problems?

 

[CMichel]

The tc locks with cruise and od off.

On the shifting, light throttle is quick and firm, wot is firm but the shift points are a little high at 2700 rpm.



Clint

 

[inarush76]

OD?

I am a bit concerned about the voltage at the signal wires when the solenoids are on. The readings you posted indicate a marginal ground on the TC solenoid and a bad ground on the OD solenoid circuit. There should be no more than . 1v on the ground side of a circuit when on. Check the wire from the trans to the computer for high resistance as well as the grounds on the vehicle. What is the voltage on the signal wire when using the toggle? It is possible you have simply had a solenoid give up. You can put your pressure gauge on the OD port (opposite side from Governor port) and see if pressure shows up when the OD signal is given. That would tell you that the solenoid is working, the valve is stroking and fluid is going to the OD piston. Let us know.

James

 

[CMichel]

I don't know what you mean to check resistance from the computer to the trans. The voltage when using the toggle is 13. 5 which is the same as the middle wire. The pressure on the od port reads 0 till about 45mph then a steady 34 psi.



thanks, Clint

 

[CMichel]

Inarush76, What do you think is the source of the problem?



Clint

 

[WaynesWorld]

OD GONE

CM,



I'm not sure about the 94 trans but my 96 had the lost OD awhile back. It turned out to be the throttle position sensor. I was putting the linkage back on when I must have hit the clip. The TPS registered not working during a trans scan. By the way did you do a trans scan? It only cost me $20. I reached under the linkage where I found the clip just sitting there. I just replaced it & everything was beautiful again in----



WAYNES WORLD

 

[CMichel]

Thanks Wayne's World, I'm scheduled monday to have the electronics checked out at dodge. I'll post if they find anything.

Clint

 

[WaynesWorld]

check out time

CMichel,

I went to a trans. place because it was only $20. Check the cost first, it could cost a bundle at the stealer.

Good Luck.



WAYNES WORLD

 

[Extreme1]

You can check for trouble codes yourself. key on, key off 3 times and leave it on. Count the flashes. The codes are in the service manual.

 

[CMichel]

Thanks for the replies. I took it to the dealer and he didn't find anything wrong with the electronics, so I called Bill K. to recommend a shop as close as possible. He recommended a place a couple of hours away, so I called and got an appointment for next monday the 20th. I'll let you know what happens.



Clint