Hello. I have a 1993 Dakota with the 5.2 2wd and Auto tranny. I have an intermittent problem with the truck shifting into OD. When I first start the truck and run it for a while, it will not shift into overdrive. Sometimes when I stop and turn off the ignition for a few minutes, then restart and drive off it will shift into overdrive. Also sometimes I will hit a bump in the road, or make a sharp turn and it will start working. Once the overdrive starts working, the switch in the dash seems to work as it should. I can turn the OD on and off with no problems. I have checked some of the electrical connections at the computer, the firewall, the transmission speed sensor and the neutral back-up switch. Everything looks okay. I have a chilton manual, but it's not very helpful. Does anybody know where I can get a detailed wiring diagram for the OD circuit? Is there a relay somewhere that controls the OD. From what I understand about the OD in these trucks is that it is controled by the computer. Does anybody know what wire it is and where it goes into the transmission. Is there a solenoid in the transmission that could be bad, or a temp switch somewhere? Is there another sensor that controls the OD? On the right side of the firewall there is a connection with what looks like a relay would go, but there is nothing there. I don't know what that is for and I don't think it is related to my problem, just wondering what that empty connector harness is for. Thanks for any help. This is driving me crazy [&:]

Chris

 

OK, there is a relay for the system. It is located in the Power Distribution Center (to the rear of the battery box). It's called the Electronic Transmission Relay (but, on the underside of the PDC cover, is shows it as the Radiator Fan Relay," don't be alarmed, the 2.5L I-4 uses this spot for it's fan relay, and the V-6 and V-8 use this spot for the transmission relay).
I doubt its the relay, but, to test this, you can exchage it with a known good relay (the fuel pump relay or automatic shutdown relay would be a good one to exhange with, since if during starting of the engine or during engine operation, the relay should malfunction, you would know right away because the truck would die).

Most likely, it sounds like a faulty connection or a faulty part. Since wire tracking is cheaper, I would start with that.
I have attached wiring diagrams (which, are a little fuzzy... camera is acting weird today).
If you need assistance, feel free to post back. (FYI, when you see Powertrain Control Module, C174 [a.k.a. connecer B, thus "B30" and "B11" like you see on the bottom of the first picture] and C175 [aka connector C], I believe connector C is the one that is furthest rear. There are three big connectors on the PCM).

There is a connector or two on the right side of the firewall (passenger side) that are for "plant use only." If you could provide a picture of the connector and the area it is in, that would be best.

 

Thanks so much for the reply dodgerules86. I am going to check the relay and then try to trace the wires back. How do I download the attached wiring diagram? I don't see it. I will report back with my findings. Thanks again, Chris

 

Here is a picture of the connector on the rightside firewall.

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[IMG]local://upfiles/42302/40F619571E3245908040D6372FFC7AFF.jpg[/IMG]

 

Okay, went to check the relay. There is no relay in the spot marked Radiator fan relay. No wiring in that spot at all to put a relay, so not sure?? Could the relay be somewhere else?
Thanks

 

The pictured connector is the on-board diagnostic connector.
Regards,
Greg

 

It appears that I forgot to attach it. Well, I will attach it this time.

The connecter is a "factory use only" diagnostics connector.

[IMG]local://upfiles/948/0B63E77126C74B3E80750E8ABDC7715F.jpg[/IMG]

[IMG]local://upfiles/948/5AE0DB64710942CAA07806AAC6FCE6B8.jpg[/IMG]

[IMG]local://upfiles/948/9711302A5E8C4BB2863646C7B8B172CD.jpg[/IMG]

 

Thanks for the wiring Diagram. I'm still tracing wires back to the transmission connector. I did find that. Still don't see a relay though, even though it shows it in the diagram. [&:] Thanks

 

Progress update: Well, I checked all the wires and connectors going to the transmission. Everything looked good and I had continuity from the 3 prong OD connector (all three wires, orange/green, blue, orange/black) to the PCM. I retaped all the wires and reinstalled, still no overdrive. I guess I'm going to change the solenoid and go ahead and change the fluid and filter while I have the transmission pan off. From what I have found online, the blue wire has 12V and the PCM grounds the orange/green for OD and the orange/black to TCC lockup. My TCC lockup works fine. Hopefully the OD solenoid is bad, but as I said in my first post, sometimes the OD works. I think the two solenoids are made together, but not sure about that. If anybody has any more info on the solenoid, please let me know.
Thanks

 

Second update: Well, I dropped the pan to install the solenoid pack (the OD solenoid and TCC solenoid are on the same mounting bracket). I had to remove what I think is the 3-4 accumulator on the side of the valvebody to remove the plug connector that the outside connector goes to. Upon inspection of the 3-4 accumulator, I just happened to take the bottom plate off of it. The spring inside was broken in two pieces. The small piston was okay. I called my local transmission parts source and the lady said the broken spring is a common problem with these transmissions. I thought for sure I had found my problem, but no luck. I installed the new solenoid pack, the new spring, new filter and filled with ATF+4. Test drove the truck for about 25 minutes with no OD. Then I came to a stop sign, turned right, got back up to about 45mph, and bam, the OD starts working. Worked all the way home. Got up this morning, no OD. Started out on the interstate to work for about 25 minutes, and slowed down to merge into traffic, back up to speed, OD starts working again. Worked fine all the way to work. I even pushed the OD several times and it works perfectly. So, I'm at a loss pretty much at this point. I may change the vehicle speed sensor in the tailshaft of the transmission to see what happens. Oh, on a side note, the factory radio stopped working in the truck last night to. Checked the fuses, none blown. Who knows. If anybody has any suggestions, please post them. Thanks