95 Caravan TCM Wiring

dodge
caravan

#1

I’ve been searching and can’t seem to find a wiring diagram for my '95 Caravan trans control module. Anyone have any good websites for that? (Its the 3.8L, A604 transmission; about 80K on a rebuild. Autozone’s online stuff just gives basic engine & body circuits).



At the moment I’m really just trying to check its ground circuit & power supply.



Back story - a while back it started occasionally being in what I assume is limp mode - 2nd gear only and no shifts, bumps into reverse or forward gears, no check engine light tho there may be hidden trans codes. This never happened while driving. Only on first starting it up. I could shut it back down, start it back up and everything was normal - never any problems while driving and it never went into limp mode while driving. The vehicle’s been sitting a couple of months & now is just stuck in this mode.



So I’m just wanting to chase what I assume to be a hard fault - bad ground or something.



So far I’ve just verified that the grounding strap to the transmission (a common problem on these) is intact & at least has continuity w/ the negative battery terminal; cleaned connectors @ the transmission; and swapped the TCM relay with a known good one with no change.



I just want to verify power to the TCM, but would rather operate with a wiring diagram is anyone knows where I can find one. Thanks.


#2

Well, now every time I try a new internet search my own post pops up at me - so I thought I’d bump it.

I was actually thinking of throwing in for an Alldata subscription (though for the $27 I thin I should get lifetime on the vehicle, not 1 yr) - can anybody say whether it would be worth it - good diagrams? Trustworthy diagrams? Any testing specs?

I’m going to call the local Dodge service dept in the AM to see if they’ll lay a copy on me.


#3

Cig, did you have it scanned yet?? A high end scanner is needed to tap into the TCM on these. They give 2 digit trouble codes.

Have you tried ATSG for the 604 manual?? There are two manuals, one of them the general overhaul manual and there is a diagnostic manual with the connectors, trouble codes, and diagrams in it. Check with ATSG.com

transman


#4

I haven’t had it scanned yet b/c I was just trying to get it back out of my driveway & on the road w/ 4 gears (its currently not inspected either). Its 2nd stop is a shop (the first one being the dump as it is full of trash).

I just wanted to at least verify that the TCM has power before I do anything else - I believe it should have more than one ground wire, maybe a 12V always hot, another switched to ignition, a 5V reference circuit, and then the PCM-TCM connection/s. Apparently problems in the harnesses for these are pretty common, so I was going to start by just checking simple things - voltages, continuity. (It doesn’t help that the only shop I know of that probably has the equipment I don’t trust as far as I can throw it.)

Thanks for that link - I’ll check it out.