Transmission rebuilt, torque converter doesn't lock | Ford Explorer Forums - Serious Explorations

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Transmission rebuilt, torque converter doesn't lock


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April 14, 2008
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I just rebuilt my first A4LD, and it seems to work just great. Thank you Glacier for all the info. I coupled your thread with the factory manual and everything went very well.
Then came the test drive, going down the road it went through all the gears shifting great till it come time for the torque converter to lock, then I noticed it wasn't locking. It was replaced with a rebuilt one on installation, so I was wondering what to do for trouble shooting to make sure I didn't overlook something during the rebuild. Thanks in advance.

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Is your brake pedal properly adjusted? You aren't riding the brake, are you?

Next step for me would be to get the factory manual and start my pinpoint tests. Try and determine if it's a trans problem or converter problem. Where did you get your converter? Reputable place?

Good point, at last I know the brake lights aren't staying on. Right now I'm away from home to double check that. I'll let you know for sure Saturday.

Hey Don, there are a few things that have to happen for the converter to lock. Do a search and you'll see that others have had this problem as well.

The engine has to be up to a certain temp (could be a bad temp sensor), the VSS has to see a certain speed, throttle position sensor may be malfunctioning, your wiring to the solenoid may be the problem, did you replace the solenoid? Were you having this problem before you did the work?

Thanks for the ideas. I finally got to get to it today breaking out the EVTM and the VOM checking the solenoids. Both checked out at about 30 Ohms. So next was checking out the circuit as the car was going down the road and no voltage was being applied to the solenoid for converter lockup when we was cruising at 55 MPH (I had a friend with me for safety). Then I had him short the white wire for the solenoid to ground and that confirmed that the mechanical part of the transmission was working and locked the converter.
Before doing all this I did verify that the brakes weren't the culprit by checking them and there was no brake lights on. So I think we are good here.
The vehicle speed sensor checks out good.
As for the answer to the question of having this problem previous if I remember right three years ago when the car was parked it seemed it did this before the tranny started to malfunction. Then the foundation collapsed in our house, and we had to rebuild our home. I spent those years finishing out the inside.
Now I want to fix this POS for a work car, living out in the country and driving 17 miles to work, I kind of need a 4WD to get to work.
So tomorrow I'll do the pin out tests on the temperature sensor and throttle position sensor.
I performed the KOEO self test and come up with 111 system pass.
Any other suggestions would be greatly appreciated. Thanks again.


As for doing a search on the subject I come up with only one other incident that didn't get anywhere, unless I'm overlooking something.:rolleyes:

Sucks about the house. I guess if you have the ford manual you're reading the same pages I am so good luck!

At least it's electrical and not a problem with the converter or transmission.

Your right about the tranny or converter, but going through the EVTM I noticed some miss prints on the brake switch schematics, if your books are old enough you will see how the circuit between the speed control references between the EEC and the brake switch there are some discrepancies in particular to pin 2 and pin 8 on the EEC.
I couldn't spend time today with it but what was pondering in my head as to why the EEC isn't allowing the circuit to complete which would be as mentioned before, the brake circuit, and maybe WOT relay stuck. Everything else to me would flag the check engine light(MIL). I'll try to keep everyone posted as this goes. Please let me know if anyone has some info on how this part of the system works. Don

As for the house, I think it was a God send for how that come out. The house that was here was built in the early 1900's and needed remodeling bad, so in the end everything come out good. Thanks for your concern though.

I don't have the EVTM, I have the A4LD reference manual. If there is anything that I can help you look up specifically let me know.

Thanks Wood, but I think things are deeper than expected. Tonight I went through the one known circuit that directly affects the torque converter unlock, the brake circuit. As said earlier the brake lights work only when the brake peddle is depressed. So I double checked pin 2 the light green wire on the EEC IV, and verified that it energized only when the peddle was depressed. Then here is where everything went haywire. I turned the key to the on position, and boom the meter went to 9.5 volts then I depressed the brake peddle and the voltage jumped even higher. Then I read the manual even more to locate the other systems that shared the same circuit and started unplugging ABS module, triple function switch shorting block, cruise control module, removing the fuse for the turn signals, even the center rear brake light. And still the meter read 9.5 volts with key in run position.
So right now I'm gathering more thoughts on what to do next. I think tomorrow its time to go for the splice if you can locate it for me that would be very helpful, it's splice# S212 in the EVTM. If I can find it and cut all the wires coming into it I think we can isolate which circuit its coming from. My next guess is we have two wires rubbed together. Thanks for helping.


Sounds like you are on the right track. I looked through the diagnosis section of the transmission manual but you have already gone deeper than it does. I don't have any info on where the splices are, the only info that I have is something that may or may not be of any use but I'll give it to you anyway.

This is the list of the possible component faults that are in the A4LD manual.

- Electrical inputs/outputs
- Powertrain Control Module
- Vehicle wiring harness 3/4 shift solenoid
- Torque converter solenoid
- Engine coolant temperature Sensor

Hope it ends up being something simple and cheap...

I think your right about going in deeper than the manual. The EVTM says splice S212 is 40mm before the interior fuse block take out on the main harness, which puts it clear up in the dash behind some kind of plastic conduit, very difficult to get to. So, I took a short cut by cutting the wire to the EEC, and went for a test drive. Still no lock up, that leads me to believe that the 9.5 volts could be some sort of reference volt, maybe.
This could lead to your possible causes list. The EEC test I performed was the KOEO test. I didn't do the KOER test. So I think it's time to step back and do this.

Interesting, I was kind of leaning towards the engine sensors , I don't think you checked then yet did you? TPS and ECT (Engine Coolant Sensor)

I'm guessing the ABS is working?

Sensors are a good point, but one other thing I failed to mention is I exchanged the motor with another one I have when the transmission was installed. So if memory serves me well (at times I wonder though) the three years ago when I parked it after the other transmission give out the torque converter did the same thing. But this weekend I'll go through the sensors better for you.

And the answer to the ABS question is no, it isn't working either as well as the cruise control. Didn't care about those things I guess.

I'm still curious about the rouge voltage to the EEC though and still working on it. I went through the wiring diagram(I have that too besides the EVTM) and I see no reason for the 9.5 volts in that circuit.

Since I need this car for work now I'll have to save this more in depth work for the weekend.

The rear wheel/4 wheel antilock sensor in the rear-end is one of the sensor inputs needed by the transmission. The vehicle speed sensor at the end of the speedo cable is used for the cruise as well as the transmission too.

The VSS could be the problem with both the cruise and torque converter lock-up, although, if you engine isn't going into closed loop (failed temp sensor) your transmission wont lock the converter. That is so the engine will warm up quicker, I would imagine that's to help light up the cats quicker, less crap out the tailpipe maybe.

Anyway, lots of ideas to try this weekend. That 9.5 volts is weird though...

if you engine isn't going into closed loop (failed temp sensor) your transmission wont lock the converter.

Boy, I've been working on Fords for more years than I like to remember. I always learn something new. This is one of those times. I did not know that.

I'm working my way to all the testing of those sensors, but first I need to resolve the extra voltage to the brake input so we can pass the BOO during key on engine running test. As far as the VSS it has been exchanged with another that I have, and still no lockup. Then the engine coolant temp sensor it has been swapped out with the motor swap. I'm beginning to think that if we pass KOER test I have another computer to plug in and try, but with it I need to plug in the barometric pressure sensor, cause this computer is what came with the car. The current computer is an updated one with three digit code and eliminated the need for barometric pressure sensor. I just cant see the sensors that have been swapped around being bad. Tonight I removed the instrument gage cluster and broke out he backside of the dash there and exposed the wiring harness as well as removed the rear wiper switch, with rear defroster switch. for exposing more harness to find the illusive S212 splice for troubleshooting this short. But if all else fails I'll rewire the circuit with fresh wire, but I don't like the idea of running with a short somewhere in the harness cause you never know what else will happen. If it affects another wire to the computer. That could of caused the computer to go bad if it is.

If you manage to get codes I have a list in my big blue book... 2 digit and 3.

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As the heat of the day wears on I'm forced to come in and cool off. So I'll report on progress made, I found the source of the rouge voltage. I said earlier that I checked each of the connections made to the circuit for being the cause of this but when I got to the RABS module I just unplugged the fuses for it rather than crawling under the dash and unplugging it. Well thats where I got lazy and lost a bunch of time. Today when I was under there I reached up there and unplugged it then checked for that excess voltage, and HA HA it was gone. I guess my next question is, Is this normal? I am still working my way to the KOER test this evening.