Does your speedo work? If not the pcm is not seeing the speed and od will never be engaged. If it does work i would see if you are getting a ground (at speed45+) from the pcm to engage them. To wire in a switch you may have to just hook it up to the ground terminals going into the trans and see if it works. If not the problem is in the trans since it's getting ground and power.

 

The speedo does work, but a handful of times, on a cold start, it has taken a minute to start working, so I do have reason to suspect the speed sensor is failing regardless .

 

Looks like this is the info I need from BBB.



So nominally, the orange/white wire is the OD, and the orange/black is "emcc solenoid", which I assume is a different term for the torque converter clutch?

 

ohkayyyyyy

I wired switches into the two wires coming off that plug, took the beast onto the interstate, took a deep breath, and threw the OD switch.

Good news: Nothing exploded.
Bad news: Nothing whatsoever happened.

Tried the TCC switch. Throwing it gives me a *minor* bump in engine noise - not even close to a shift, but would (to me) imply the TCC disengaging and fluid losses causing the engine to rev up slightly to maintain the same speed. Pushing the O/D button on the dash causes the same change in engine noise.

Just to be scientific, I went to an empty straight road, stopped, then accelerated up to 70 normally, and counted the shifts. It went 1-2-3 normally, popping into 3 around 40 mph, then just revved up as I brought it up to 70. When I set the cruise and let off the pedal, I heard the same tiny drop in revs as described above.

So it seems like the TCC solenoid works fine, but the OD solenoid isn't engaging. The location of the plug makes it impossible to get multimeter probes in there to check continuity so I can't be dead certain. However, pulling the plug causes a code, so there's apparently SOMETHING in there with continuity. I don't know what to make of any of this.

 

One thing, though - Throwing the TCC switch (and cutting power to it) caused the revving up - this would seem to indicate the solenoid function isn't "powered = off" like we were thinking. Is that logical?

 

You are on the right track.

The fact that your O/D switch did nothing points to an internal problem. Either the solenoid is bad, or something else in the trans is borked.

 

It's looking that way, but there's a couple things I want to chase down first.

I can't operate the multimeter and drive the van the same time, so I'm not sure if the overdrive solenoid is getting power at speed. It sounds like the computer is switching the lock up solenoid on and off, so it could be failing to energize the od solenoid somehow.

The only alternative test I can come up with is to attach the od switch directly to a known ground like the body and see if I get anything that way. Any reason I shouldn't do that?

 

Give it a shot, and see what happens. I don't think you can break anything that way. (aside from tripping the switch when you really don't want to.....)

Thing is though, if the PCM commands O/D, and doesn't see the RPM drop it would expect, it *should* set a code..... Which makes me wonder, IS the PCM commanding O/D at all???? I think you would need a pretty decent scanner to see that bit of data.....

 

This PCM has already taken at least one ****. Previous owner had to add a voltage regulator because the one on the PCM had failed. The computer didn't even notice it had been cut out of the voltage loop for MONTHS and is now permanently throwing a code 41 (charging circuit open) as a result.

I trust the solenoid further than I trust the computer, is my point. Though there's a lot of wishful thinking involved, as I have a long trip in two weeks and I cannot afford any sort of transmission work right now.

 

Depending on how far you are going, the repair might cost less than the gas it will cost you not having o/d......

Yes, I am just a ray of sunshine, ain't I?