A4LD - no torque converter lock up

Hi,
Looking for advice. I have a '94 Ford Explorer Sport. Has about 176k miles & A4LD tranny. About a month ago the tranny has been acting up after it gets warm (5-10min). Took it to a transmission shop to see what was up. They said the torque converter lock up was not working properly. It shifts just fine until about 45mph then it can't seem to decide what gear it wants to stay in. (3-4 or OD). If i barely accelerate, it'll jump back to 3rd & if i hold the throttle, just barely letting it decelerate, it'll shift back into 4th followed by sometimes OD.

At the moment, my explorer is torn apart in my garage, as it was needing front and rear suspension replaced. (My husband is a mechanic, but doesn't deal with transmissions. I just do simple maintenance stuff.) I have acquired a junk explorer to swap parts with.

Now my question is this, after doing some reading, i am wondering if my tranny troubles could be fixed by replacing the 3-4 & tcc solenoid or maybe it is something electrical? OR should i just swap my tranny for the junk explorer's one instead? (I do not know the state it was in before the engine went caput.)

Thanks in advance.

I'd probably start by getting the front and rear suspension back together and see if you can pick out where the problem is at.

Because the 3-4 shift and TCC lockup are electronically controlled, I'd probably start by pulling codes to see if there is anything stored that would indicate if there's a problem in engine management that could be contributing to the issue.

Then hook up a voltmeter across either solenoid. Then use the output state test to see if the computer can communicate with the transmission solenoids (see my notes on pulling EEC-IV codes for how to enter the output state test mode). You should be able to see the voltage drop across the solenoid change from 12 V to 0 V as the PCM changes states.

If the PCM appears able to talk to the solenoids, a test drive would allow you to see if the computer is choosing to command the shifts (voltmeter still measuring voltage drop across the solenoids). If the PCM is commanding the shifts but the transmission is not responding appropriately, then the problem is inside the transmission. If the PCM is intermittently or otherwise not commanding the shifts as it should, then further inspection of the wiring/engine management is in order.

Intermentant DTC 214

Don't know if this would be related, but months prior, i would get a check engine light that would come on for a few minutes. Took it by autozone to find out the error codes. I got this- "Diagnostic Trouble Code (DTC) 214 indicates an error has been detected in the Cylinder Identification (CID) input signal. Possible causes:
• Open or shorted harness.
• Damaged Camshaft Position (CMP) sensor.
• Damaged Crankshaft Position (CKP) sensor.
• Damaged Ignition Control Module (ICM).
• Damaged Powertrain Control Module (PCM)."

I find it interesting that a possible damaged PCM was on the list. But what I'm wanting advice on is, do you think it's more trouble to track down my tranny's trouble or just put the spare one in? (not entirely sure of the spare one's state.) If i put the spare tranny & the trouble is in the PCM would this make the spare tranny act up as well? My husband wants to put the spare tranny in cuz he says with the suspension out of the way, it would be easier, but i think we should rule out any possible electrical issues first. Why remove my tranny if it may not be necessary?

If i put the spare tranny & the trouble is in the PCM would this make the spare tranny act up as well?

Click to expand...

Yes.

How certain are you that the spare tranny is as in as good a shape as the existing tranny? One concern I would have with swapping another tranny in is the fear of swapping in something with different/worse problems (it is an A4LD after all).