mikey2183

I have a 94 GC we just put a new 5.2 motor in. Runs great. Car used to belong to my son. He had the tranny rebuilt and it shifts great except there is no overdrive. The OD light does not come on when pushed. No shifting into OD. While we were changing engine, found the a/c evaporator was leaking so we had to take the dash out to replace the evap.

The od light is not working and thought maybe we left something unplugged. Checked all connections and all ok. My son does not remember if the OD light worked after the tranny was rebuilt.

We have checked the tranny fuse under the hood and it is okay, verified by meter.

Some one mentioned you can get tranny codes like the engine codes by turning the ignition on & off 3 times and reading the number of flashes of the OD light. Howver, since the OD light is not working, can't read codes.

Not sure if the OD switch is bad. My son did say the guy that rebuilt the tranny said something about may need to get a new computer as he could not clear some tranny codes. Not sure if he meant the tranny TCM or the engine PCM..

My questions are:

1. How can I read the PCM codes.
2. How can I determine if the OD switch is bad and how probable is that?
3. Would a bad PCM cause the OD light & the OD itself not to work yet, allow the tranny to shift perfectly in gears 1-3?
4. Any suggestions on what to do next?

Thanks for any help out there,

Mike...

ol"blue

1. Here's how you can read your codes. >>->Jeep Horizons :: View topic - Jeep Computer codes (OBDI & OBDII)
2. ?
3. I doubt it. It has little if anything to do with the trans. That is the job of the TCM,
4. ?,
Does the torque converter still lock up as it should?
Are you sure the harness was reconnected to the trans and isn't damaged?

whowey

Well... My light only comes on when the OD is switched off.. and its just the little orange light right above the button.

94 GC 5.2 Laredo... A Limited might be different.

ol"blue

On my '97 GC Limited w/5.2L, the OD button lights up green when pressed to turn off the OD.

mikey2183

I am assuming the torque convertor is locking up. It runs great and shifts great. The orange OD light does not come on anytime I push the OD button and there is not any shift into overdrive. It acts as if the button does not have power to it. However, I am not sure. I have checked all the harnesses I can see and do not see anything loose. Since the wiring harness fitting that plugs into the OD button also controls the rear window defrost and the rear windshield wiper, I do not know which wires would control the OD button.

I have read that the OD selenoid could be bad or the TCM. However, I am not sure if they were bad that it would cause the OD button light to not work. Not sure had to check power to the OD button. I know there is power in this harness plug as the wiper and defrost works fine.

Anytime you remove an entire dash and entire engine and reinstall, there are sure to be a few problems. However, I am not sure that the OD was working prior. My son cannot remember if the OD was working before the rebuild. Also, the comments made to him by the mechanic said he may need to replace the computer as there were some tranny code errors he could not clear off the computer...?

Thanks,
Mike...

ol"blue

The manual mentions the transmission control module in the diagram. Circuit K22, and again in ground circuit K4. I don't know what that means though.

ol"blue

It doesn't have a diagram for the TCM itself though.

mikey2183

I appreciate the engine codes. I have already checked the codes through the engine light and their are not any errors. I understand you can check the tranny codes through the TCM the same way but since the OD light is not working, I cannot see it flashing any error codes. I cannot confirm that you can check the TCM codes separately. However, the tranny rebuilder told my son there were a couple of error codes in the computer and we still don't know which computer he was referring to. I do not see any engine code errors.

As to the OD light not coming on, I cannot figure out which wires to check. Or, if the OD switch itself is defective. I am afraid I will end up doing "replacement diagnotics" which will cost a small fortune..(grin) ...

Thanks,
Mike..

ol"blue

If you send Cherokee 4.0 a PM asking for what you need, he can send you (via e-mail) any wiring diagrams you need. (Here's the thread where he started doing that. >>->https://www.cherokeeforum.com/f2/wiring-diagrams-22194/)

ol"blue

Or storm101 can do it too.>>->https://www.cherokeeforum.com/f2/wir...-22194/index5/