Engine/Transmission (1998.5 - 2002) Transmission issue 2001 3500 AT dually with 180,000 miles

[BTMaltby]

If I am running a steady speed around 45 mph the transmission is bouncing between OD and the next gear down. I have read about the key trick but don't know the procedure to determine a trouble code? Thanks

 

[DAN V]

key cycle

If I am running a steady speed around 45 mph the transmission is bouncing between OD and the next gear down. I have re



ad about the key trick but don't know the procedure to determine a trouble code? Thanks

What you need to do for codes is cycle the ignition key 3 times. Make sure you have pen and paper handy to write the codes down as they only appear for a few seconds. After you write codes down look in the service manual (if you have one). You should be able to get your codes this way. The codes will appear in the odometer section just after you cycle the key.

 

[BoeingDiesel]

If I am running a steady speed around 45 mph the transmission is bouncing between OD and the next gear down. I have read about the key trick but don't know the procedure to determine a trouble code? Thanks

Sounds like you may be experiencing the TC lock/unlock anomaly. If so, there is plenty of reading on the TDR on the issue.

 

[cerberusiam]

If it is actually dropping out of OD that is sually caused by an APPS problem. You should have a code for it but that is not a given. Then will cause problems and frequently not set a DTC.

If it is the TC lockup that is fluctuating then you have some digging, cleaning, and decisions to make. Need to determine if it is lockup or OD that is jumping in and out first.

 

[BTMaltby]

Just did the key code and got - "P done"

 

[cerberusiam]

Just did the key code and got - "P done"

Normal, it slikely not APPS or solenoid then. Check to make sure it is dropping OD and not just lockup.

If you have not done so, a new transducer and gov solenoid might be the solution if it is actually dropping OD.

 

[BTMaltby]

Not sure what lockup is ? Also read that a worn alternator could be creating the problem? Mine is now 12 years old with 180,000 miles. Looked on EBay and found a replacement (new) for about $120 delivered in 1 week or less. That would be relatively easy fix. Am a little concerned about the quality of the replacement. Wonder what result others have had? The transducer and gov solenoid are original as well. Any estimate on replacement cost? I could ride my bike down to Genos since they are only 65 miles away. Just wish they were open on Saturday.

 

[cerberusiam]

Lockup is TC lockup, that th eusual problem at that speed and steady throttle when the truck ages. OD bouncing has different results and usually different sources. You need to figure out what problem you have first.



Lockup clutch bouncing will give you a 200-300 rpm fluctuation, OD bouncing is more like 800-900 depending on how fast you are going and how much throttle is being used.



Lockup clutch problems are the usual culprit and can have many sources, but, the main problem is noise in the wiring harness that the PCM interprest as a signal to drop lockup. It could come from the alternator, batteries, bad grounds, installed aftermarket equipment, or a bad APPS signal. You have to approach it systematically or it will drive you nuts and cost big $$$ for no result.



Typically the place to start is the batteries and grounding points. Make sure your batteries are both good, tested with a good load tester. Make sure all grounds are tight and clean. Scraping them is advisable. Make sure you battery cables are clean, tight, and have no internal issues. The cross over cable can be problematic and it needs tested for resistance to see if it is bad inside the clamp. Same with battery cables. A lot of issues stem from the noise created by a bad connection inside the clamp.



Next step would be removing the ground wire from the passenger side battery and the alternator charge wire from the control harness. Thes 2 wires are the source of the electircla interference and simply moving them will frequently solve the problem. The alternator charge wire gets cut at the alternator and reroutes over the radiator support to its anchor point below the driver side battery. The passenger side ground wire gets cut and moved tot he firewal then over to the drive side of the engine. It connects to 3 gounding wires in the harness for the PCM and ECM so find that junction and make your connection there.



The alternator would be my 2nd to last piece to change if it is charging well. Don't buy a reman as they seem to be as noisy. A high quality new alternator is the best route and relatively expensive so save it for last.



Last resort if nothing else works, a triple disk TC. They take long enough to lock\unlock that signal noise usually does not effect them.

 

[BTMaltby]

Thank you so much for the detailed answer Cerberusiam. Just tested it running at 40-50 mph steady and the bounce is around 200 +/- rpms. So I will first pursue the TC lockup issue. Once again thank you for pointing me in the right direction.

 

[BTMaltby]

Well, seems like the problem is solved. I just returned from a test drive and there was no repeat of the problem. I cleaned the ground wires running to the body on both sides. Also cleaned the main ground wire and two wires coming off the driver side battery. My mechanic had recently replaced that one with a lead style clamp. I found alot of corrosion in the copper of the main ground cable and wondered if there isn't a better attachment method.

 

[cerberusiam]

You need a battery cable without the temporary ends or you will just have further problems. Time for a new cable there.