Transmission and COMBI Help

[bmdubya1198]

ECU B-26 --> TCU B-15 should read zero ohms

ECU B-26 --> TCU B-30 should not read zero ohms. I can't say with any certainty what it should read since the modules are schematically a black box but TCU B-30 is ground.

What this suggests is that the wire between ECU B-26 and TCU B-15 is cut and shorted to ground. It could be another wire that it is shorted to or it could be something on the case but likely the former since the ECU cage is plastic.

Can you post up a picture of the ECU / TCU cage? I'm trying to visualize the extent of the collision damage that would tear up the wiring inside the cage.

Have you removed the case from around the ECU / TCU modules? Doing so will reveal wiring under the connectors and some things may become very obvious when you see the wiring bundle there. If you do have it removed post up pictures of that as well.

The -117 Ohm thing suggests that there is still battery voltage present since there really is no such thing as negative resistance. ECU B-23 goes to the temp gauge, not the ECT sensor.

...Lee

When I said there was no response from ECU B26 to TCU B15, I mean that the multimeter stayed at 1, not 0. Which is why I was wondering about that.
I had removed the cage and everything the other day, and again today. I did find a broken wire just a little while ago that had one end coming from the ground point underneath the pass. side headlight, and the other coming from the loom, possibly to the battery? I repaired that wire, and there was no change with the car. There aren't any obvious wire breaks on the bottom of the connectors. Like I mentioned before, the only wire connecting the two modules is a red wire, traveling from ECU B26 to TCU B30. On B30, there is another red wire connecting that appears to run along the main loom out of the front of the box.
I'll post picture of the cage later. The back bracket is broken, but the cage itself doesn't look like it could have cut into anything.
That reading was +117 ohms, NOT -117. The battery was disconnected, so I don't think there could have been any voltage. If the B23 wire doesn't go to the coolant temp. sensor, that seems strange that I even got a reading there.
I had the car running for a while this morning, and I noticed that the ECU was warm, as expected. My TCU, on the other hand, was still cool. Is it possible that it may just not be getting power? And how to I test if the TCU is getting power?

[Ozark Lee]

Are you sure of your pinouts? I can't recall if the sockets have the pin numbers molded into them or not. On a Volvo P80 the ground wire is never a red wire and it is almost always a black wire.

The ECU pinout in the mobisx post is from the ECU itself perspective, not the socket. The pins flip left to right on the socket.

...Lee

[bmdubya1198]

Are you sure of your pinouts? I can't recall if the sockets have the pin numbers molded into them or not. On a Volvo P80 the ground wire is never a red wire and it is almost always a black wire.

The ECU pinout in the mobisx post is from the ECU itself perspective, not the socket. The pins flip left to right on the socket.

...Lee

I'm not at all sure about the pinouts. I was just doing what I could with what I had... which is very little. Thank you for throwing in that detail... either I wasn't reading through the document, or they need to be a little clearer. The sockets DO have numbers on them (on the edge(s)), but not all of the pins. And those numbers don't seem to correlate to the pins they're next to. This is also why the TCM pinout is so important to me right now. The "diagram" (if I can even call it that) that I've been referring to is the least descriptive diagram I've ever seen.
I probably should have cleared up that detail about the red wire a little... the red wire connects the TCM to the ECM. The ground wire I repaired was a black wire. Neither had anything to do with the other, as far as I know.
I'm apologize if anything here comes off a little snippy (or disorganized), my mind is a little scattered. This car is killing me... I woke up this morning positive and hoping to get to the bottom of this, and discovering that broken black wire got me even more excited, and now I am straight up pissed.
Thank you for your help so far!

[bmdubya1198]

I'm VERY happy to say that I have fixed my transmission! It turns out that the wires at the ECU box were not the problem. There is a square connector on the driver's side of the cooling fan that had a pin/wire not in all the way. I just messed around with it a little to put it back in, and it turns out that was the problem! I got in the car, turn on the ignition, and the up arrow light was on, as well as the orange light on the W button. I started it up, pushed the W button, and the light went off. I drove it around the block, and the transmission works great! It shifts smooth as butter, and the car has got some nice low end power compared to my cousin's T5!
THANK YOU for your help!