47RE torque convertor locking and unlocking rapidly

[MoparMello]

Just bought a 2001 2500 24v auto with 103,000. Everything was fine until one day my lock up was going in and out rapidly in drive and overdrive. Looked up a similar symptoms on the internet and a lot of people suggest moving a passenger side ground wire out from the wire loom that runs above the alternator and under the bracket. I moved the wire and reset my apps with the pedal procedure. I've only put 200 miles on so far but everything is back to BETTER than normal. Just curious if there's any other common problems associated with the haywire of the locking and unlocking of the torque convertor.

[Yankneck696]

Check the AC voltage leakage at the B+ terminal on the back of the alternator. Anything .10VAC and over is a fail.

 

Ed

[MoparMello]

The charging system seems to be functioning normally. Is it just a bad diode? Is the alternator now unreliable? Like I said I just bought the truck the alternator looks almost brand new, not that it means it's good. 

[Yankneck696]

Even new/rebuilds sometimes have the bad AC ripple, as many are done with cheap Chinese diodes. Just check it. Use a digital volt meter that reads 2 VAC or lower.

Ed

[joecool911]

I think your work around shows that the alternator is throwing A/C noise. Not good for other components like ECM, pcm. Check for AC as suggested above. I went out and got a digital VOM. I was having trouble too. But eliminated the alternator. Mine was bad ground connections. Clean your battery cables to start with. That's a cheap fix. Most of us have been there!

[MoparMello]

A bad ground will cause the ac noise or just screw with the lockup? Also after I check all grounds body and battery is it necessary to always reset the apps sensor? Lastly if all the connections are good and the alternator runs above 10VAC am I looking at replacing the alternator? Thanks for all the information, Greg.

[MnTom]

A bad ground can and will screw up lots of things. The ground by your alternator may have had a poor connection and by moving the wire it might be better for a while. A good way to check if it is the alternator is to unplug the small wires going to the aternator and then test driving it. The two small wires are what makes the alternator charge, but a digital volt meter is the best way to check. The AC noise is a big problem for the lock up.A bad ground will not cause AC noise, but a leaking diode (all to common) will allow AC to get into the system and screw with your truck........

If you have a volate reading of one tenth of a volt AC, then you have leaking doides and need to repair or replace the alternator, BUT keep in mind that a lot of "brand new rebuilt" alternators will fail the AC test right out of the box. You need to make sure that the one you get has passed the test.

[joecool911]

Bad grounds won't cause ac. Separate issue. That's 0.10 threshold, not 10.0. You won't need to recalibrate the TPS unless you're offline for 30 mins or so. But recalibrate is so simple, you might as well.

Edited October 21, 2014 by joecool911

[Yankneck696]

that is .10 VAC, as in 1/10th of a volt.

 

Ed

[Mopar1973Man]

Normal alternator

 

Failed...

[MoparMello]

MoparMan where are your test leads? on the battery? And unfortunately I don't have access to a scanner like the one in the second video.

[MnTom]

MoparMan where are your test leads? on the battery? And unfortunately I don't have access to a scanner like the one in the second video.

The best way to test is to put the blsck lead on the negative battery terminal and the red lead will go to the large terminal on the rear of the alternator. Like what was posted before, anything over 1/10th of a volt at any RPM is a failing diode and will cause problems.

[Mopar1973Man]

Absolutely correct...