Okay, I’m about to pull my hair out. I have a '94 Eclipse GS with an AT (fwd). Mine’s stuck in limp mode (2nd gear) which I originally assumed was a solenoid (previous owner took it to a shop that said that, but they didn’t check wiring). All four valve body solenoids returned proper spec resistance (~20 ohms for shift, ~3 for pressure reg, and ~13 ohms for damper clutch ctrl). So I moved to wiring and found that between the TCM and the connector for the solenoids right above the transmission had zero continuity whatsoever. Plus, the wires inputting the TCM are a different color than the ones coming out of the connector in the engine bay. so there’s gotta be another connector somewhere but I can’t for the life of me find it. Am I even on the right track here? I’ve gotten a decent chunk of the way into removing the dashboard totally to try and see about maybe getting all the AC equipment out of the way, but this feel just a little too extreme, so I’m just gonna ask y’all. Any help at all would be spectacular, thanks.
Start at the transmission… the hot area… and work backwards, not forward from the TCM. Wires fail when they get hot and flex. The TCM side is inside the car where it is cool and doesn’t move around. There is likely a connector at or near the firewall.
Here’s the image for the electrical diagram, if that helps. I’ve checked the connector outside in the engine bay (B-24) and it is fine. The only other possible connector that we could think of is C-28, but we’re unable to locate that or even know for sure if it’s in the solenoid wiring.
Re read my post.
I have never worked on this type of car plus you didn’t say if it was a turbo or how many miles on it.
Start pulling things out of the way in the engine compartment so you can trace the wires. Look for damaged wires. The engine is installed at the factory with the complete powertrain harness connected. Most of the time there will be a junction in the harness near or at the firewall.
If you keep stripping the dash out of the car, you very likely will be disappointed.
C-28 appears to be the data link connector (diagnostic connector)
C-55 and C-56 are the TCM connectors.
It’s a GS, no turbo. it’s got 115k on the odo, so it’s not too high. We’re almost certain the connector is on the interior directly after the wiring harness enters from the firewall (hence the dash disassembly) I can trace the wires direct from the tranny to the exterior engine bay firewall, and the only connector is the verified B-24. I just don’t know for sure that there’s a connector there. That’s the only reasonable explanation we can come up with at this point.
Intermediate connectors should be shown on the wiring diagram, but none are shown for the transmission solenoid wiring. Are you looking at the correct wire cavities of connector C-55 for blue, orange and yellow/blue wires?
An example of an intermediate connector is C-62, the dotted line and cavity numbers are listed.
Explain more clearly which two points in the diagram above which two points your believe should show continuity, and don’t. For example it appears there should be a yellow wire from c56-15 to B24-4. Have you measured the continuity for that path? Is the connector you think is B24 a simple 4 pin connector?
I expect the 4 pins for the 4 solenoids are outputs from the TCM, not inputs to the TCM. It’s possible a wire color change for the harness was made by the production line when you car was being built.
If the transmission was shifting ok, then one day stopped working, unless somebody fiddled w/the wiring harness, it is unlikely the problem is an incorrect wire color.
+1
I have to wonder how many times over the past 29 years the transmission has been serviced. If it is less than… let’s say… 7 times, then it is very likely that the transmission is now toast.
In any event, a 29 year old automatic transmission is now well past its design life.
Are you looking at the correct wire cavities of connector C-55 for blue, orange and yellow/blue wires?
Yep, we checked the wire colors against the Alldata listed colors and they matched perfectly on the solenoid side. We tested cavities 1, 2, 14, and 15.
Explain more clearly which two points in the diagram above which two points your believe should show continuity, and don’t.
We found no continuity between the corresponding four pins (or any combination of the four, for that matter) on B-24, which is only a four-pin connector, and C-55. The wire colors on the TCM connector, C-55, aren’t the same as the colors for B-24. We take that to mean there’s a connector somewhere in between that just isn’t listed by Alldata, which would explain the change. There’s no connector on the engine side, save for B-24, so our current best guess is a connector on the interior of the firewall, hidden behind the dash and air handling unit.
If the transmission was shifting ok, then one day stopped working, unless somebody fiddled w/the wiring harness, it is unlikely the problem is an incorrect wire color.
Car was bought with it in limp mode, so I don’t know if it was a matter of just one day not working or after a couple years of sitting starting in limp mode.
The diagram above is not perfectly clear, but it looks to me that the B-24 harness is connected to C56, not C55.
The cavity numbers don’t correspond between the two. Does that matter? If not, how do I know which pins on C-56 correspond to the B-24 wires?
The above diagram suggests it is C56: 1,2,14,15
I’m not sure if I’m reading it right but to me it looks like C-56 contains pins 31-49. Are you meaning C-45?
I see what you mean. hmm … seems it is hard to tell from the diagram which connector is connected to B24 . The folks who make the wiring diagrams have conventions the use to try to make the drawing less cluttered. The conventions also tend to be manufacturer specific. In this case the less-clutter is also causing some ambiguity. Suggest to look at the other possible connectors, see if one of them has wire colors which match up to pins 1,2,14,15.
My olds went into limp mode on the highway. Towed it to a trans shop where they replaced the solenoid pack. No problems after that.
I dunno on wire colors. I was running a new injector wire on my Buick. Factory manual said the black wire. Opened the loom up and three black wires. Picked the wrong one. Shop corrected it.
So just sayin think I would have a shop look at it especially if you can slowly drive it there.
Make sure ALL your grounds are good and no corrosion anywhere…
Dealing with a 09 Cobalt that would not shift after doing some work on it and then letting it sit for 5 years (stupid long story)… Ran a jumper wire from the TCM case to a good ground and now it shifts normal… Not 100% sure why or what happened and at this point, I don’t care, it drives again… lol… I will look into it more later…
Would a lack of proper grounding from the TCU result in the lost continuity in the harness? I’m not at all the most knowledgeable in electrical principles, but I think that even if there was no ground, the harness should still have continuity between the two points. (connector plugging into the TCU and connector attached to the solenoids). We’ve tried every pin combination possible to make sure we’re not misreading the diagram, but we’ve got nothing from any of the TCU pin outs and any of the pins on the connector to the solenoids.
This is what I’m seeing for a 94 Eclipse 1.8L configuration
From the TCM located behind center of IP, looks to be a 46 pin connector, pin 1 is red wire, pin 46 is white wire.
pin 1 , red wire, to pin 2 of valve unit (torque converter clutch)
pin 2, orange wire to pin 3 of valve unit (shift control, non-turbo)
pin 15, yellow wire to pin 4 of valve unit (shift control)
pin 14, blue wire to pin 1 of valve unit (oil pressure control)