Intermittant shifting problem--'95 GC

[4breezes]

1995 Grand Caravan, 3.3 engine, auto transmission (A604?).

We replaced the transmission about two years ago with a factory remanufactured unit, for all the normal reasons. A couple times since then, it has refused to shift upward to a higher gear.

Yesterday was a good example. We were on our way to Costco, and I realized I was crusing at 4000 rpm. I stopped, then started again, paying more attention. The transmission wasn't shifting. We turned around, came home, and changed cars. When I took it for a test drive this morning all was well. It shifted just as I would expect it to.

Whats happening here? Am I looking at another problem with the transmission, a problem with sensors not telling the transmission to shift, perhaps a loose connection on some wiring, what?

This is really irritating in that it is so intermittant. It may not happen again for a month or more. How can I find the problem other than waiting for it to become more critical?

[RIP]

Sounds like the van went into what's called limp mode because a problem was detected in the transmission or it's sensors. It won't shift above second gear. This helps prevent serious damage to the transmission. Hopefully your service engine light came on meaning you have a stored fault code. Even if it didn't you need to read the codes. I think 95s still used the old OBDI fault detection system so a scanner won't help. OBDI scanners are a rarity. You'll have to do it manually by cycling the ignition key from off to on (not start) leaving it on. Now count the number of flashes of the service engine light. All codes are two digits. For example code 21 would be flash, flash, pause, flash. Muliple codes are divided by a longer pause. A code 55 means the test is complete.

Besides that you can inspect all the sensor connections for security and corrosion. You could try resetting the tranny by disconnecting the battery. Just remeber when you do that any codes will disappear.

[4breezes]

Thanks for the good reply.

Yes, it acted as though it went into limp-home mode. It acted just about the same way it did before we replaced the transmission. But this time it has come out of it and runs as normal again. Prior to replacing the transmission it would not recover from limp mode. Now it is intermittant at worst, hitting only rarely.

I ran the codes this morning, cycling the key. There are no stored codes. I get only 5-5. When it went into limp-home mode the other day I got no "check engine" light. So, I'm getting a problem with no indication of the cause, beyond the symptoms.

I'll check the ground strap today, and start looking for sensors. What sensors am I looking for, how many, and where? An actual list, with locations, would be a great help.

Thanks.

[RIP]

Input and output speed sensors on the front of the 4 speed tranny. Look down past the air ducts on the drivers side front. If it comes to it these sensors cost around $20. Check the Transmission Control Module (TCM) connector too. It's on the passenger side fender wall. If you ever see the service engine light, check the codes right away.

Best diagram I could find: http://geekswithblogs.net/lorint/arc.../21/63765.aspx Disregard the narrative. The engine is on the left and the battery is at upper right. Sensors are below. Hope it's simular.

[4breezes]

I think I may have found a problem, perhaps the root of this shifting problem. I've read about a transmission (I think) ground by the starter. Its been mentioned rather prominently in other posts. I believe I found it. It wasn't attached under the bolt, but just wedged on top of it, above it in the picture (if I can get the picture into this post), and apparently held there simply by the tension of the wire. In the picture below I moved the grounding ring away from the bolt for clarity.

I'm going to assume that this is a ground wire which should be under a nearby bolt. I'm going to further assume that it is the transmission ground wire.

The transmission was replaced in Maine a year and a half ago. Following that the car was driven very little for the first year because my wife and I were in California. Last Octorer, four months ago, we drove the car from Maine to California, a distance of 3500 miles. All that time the ground wire was apparently held in place by the tension of the wire and the wind pressure of the car as we drove. Does this really seem possible? Are we really that lucky?

I'll try to post a picture here.





If my assumptions are correct, have we done any damage to the transmission? This is of course, a very important question. Is this the root of the problem? But, most importantly, have we damaged the transmission in any way?

Should I simply support the transmission, undo the bolt to the right of the ground ring, install the ground ring on the bolt, and be done with it? Is the fix going to be that simple? How does all this work into the warentee on that transmission? Will it affect the warentee?

Thanks for all your help and opinions.

[tempfixit]

Yes I would remove the bolt clean it up with a wire brush and clean the wire connector and insert bolt thru connector and bolt to transmission. I am not a transmission expert by any means but I would not suspect this would cause damage to transmission. I assume you took pictures of the wire not being attached in the correct manner before moving it for picture on this post. I would think pictures should be sufficent evidence of improper installtion by shop that did the work, IMHO the shop needs to cover damages if any occur to transmission.

Good Luck