Coming out if lockup

[Cummins12V98]

01 auto 3.55’s OD off around 30mph it comes out and of lockup under light acceleration. Same thing in OD around 50-55. This just started happening.

160k on original trans. Other than this it shifts perfectly. Around 35k since full AMZ/OIL, filter and band adjustment.

 

[Cummins12V98]

30 views and no ideas. Thought this one would be easy.

 

[petersonj]

Have you heard of the the W-T wiring modification? If so, has it been done on your truck? The second generation 24 valve trucks are notorious for electrical interference problems that are related to factory wiring. This interference can create havoc with the operation of the ECM and PCM. Inadvertent unlocking and relocking of the torque converter is one of the symptoms. The wiring modification consists mostly of rewiring grounds and rewiring the alternator output to the passenger side battery.

Is your truck still running on the original APPS? Has the BD capacitor been added to the APPS circuit?

- John

 

[BigPapa]

Could be any of a number of things. What pj said, brake light switch, APPS, ABS Sensor, corroded grounds, etc.

 

[Cummins12V98]

100% stock. Never missed a beat until recently.

Don't think this is electrical as it only happens with light pedal load at lower speeds and around 14-1500 rpm's.

Is there a solenoid that could be going out causing this?

 

[AH64ID]

Have you checked for AC noise on the alternator?

 

[Cummins12V98]

No I have not checked anything.

I do believe what everyone is telling me that it's an electrical interference of some sort. Happened to talk to the trans guy that has a good rep today at the local dealer. He said to cut the ground wire for the APP sensor and make a loop to a body ground. He also mentioned shielding the ground wire that crosses at the radiator. He did say if I replaced the alternator that should fix the issue also.

Honestly don't know where the APP is located or where this ground wire is that needs to be cut. Seems like this would be the first thing to check?

 

[petersonj]

He also mentioned shielding the ground wire that crosses at the radiator.

This is one of the many bandaids around that usually masks the problem.

He did say if I replaced the alternator that should fix the issue also.

If you were to perform the repairs in the W-T wiring modification, chances are you will find that the alternator is fine. There are many sources for the electrical interference. Many people who have done the wiring modification found that no further repairs were necessary and their truck performed better in all driving aspects in regard to throttle response, cruise control, automatic transmission shifting, etc.

Here is a link to the W-T wiring mod. Read through it - there is a lot of detail - you may have to read it a couple of times. There are good illustrations showing the different problems and more illustrations showing how to repair the problems.

https://mopar1973man.com/cummins/ar...erence-vp44ecmpcmpdc-plus-tc-lockunlock-r567/

I highly recommend performing the wiring modification as a first step in diagnosing your symptoms.

- John

 

[Cummins12V98]

I really appreciate everyone’s help. Lots to look into.

 

[Cummins12V98]

petersonj, when I click on the link it appears there are many missing pictures.

So If I am reading this correctly I need to run straight from alternator + to battery passenger side +.

I need to cut loose the 4 ground wires from splice and solder on a connector to them and mount to back side of timing case with new bolt.

From that bolt I need to run a ground cable to - on Drivers side battery.

Also clean all battery connections.

Should I spend the $30 for the BD Diesel 1300030 Accelerator Pedal Position Noise Isolator Accelerator Pedal Position Noise Isolator ?

Please tell me the list above is correct.

 

[petersonj]

when I click on the link it appears there are many missing pictures

Well, that's a bummer. I just tried the link and it works okay for me, so I have no explanation for that.

So If I am reading this correctly I need to run straight from alternator + to battery passenger side +. I need to cut loose the 4 ground wires from splice and solder on a connector to them and mount to back side of timing case with new bolt. From that bolt I need to run a ground cable to - on Drivers side battery. Also clean all battery connections.

That is correct for all of the above. It is also recommended to install a 150 amp circuit breaker for the alternator output near or at the passenger side battery. This does not protect the alternator, but it does prevent a fire should a high amperage short circuit to ground occur at the alternator. Note that there is a 145 amp fuse at the PDC where the factory alternator output wire is connected that does the same thing.

This is the fuse that I purchased.

Should I spend the $30 for the BD Diesel 1300030 Accelerator Pedal Position Noise Isolator Accelerator Pedal Position Noise Isolator ?

No. I wasn't clear about that on my original post, but this device is another bandaid that hides the symptoms but does not fix the problem.

- John

 

[Cummins12V98]

SWEET, I will use part of the saved $30 to buy the fuse. Price went up they are now $18.99 for the two.

 

[Cummins12V98]

Where did you find this bolt? "Metric M5 with a 5/16" hex head is perfect" His chart says M5 x 0.80

I am ignorant to metric bolt specs.

 

[BigPapa]

The “normal” head size on an M5 bolt is 8mm. 8mm and 5/16” sockets are interchangeable. The 0.80 is the thread pitch, one thread every 0.80mm.

 

[Cummins12V98]

The “normal” head size on an M5 bolt is 8mm. 8mm and 5/16” sockets are interchangeable. The 0.80 is the thread pitch, one thread every 0.80mm.

perfect answer, thanks!!!

 

[Cummins12V98]

All done other than the fuse I am waiting on. I did not solder anything. I used crimp on heat shrink connectors with Di electric grease on the copper. I have a nice crimper designed for each color/size connector. I crimped on copper end to the hot wire from the alternator. I replaced the aftermarket negative battery cable connectors. I hacksawed out the OE battery connectors so they could be tightened properly. All looks neat and clean. Even placed 1/2" flex tubing over the smaller wire bundle along front of the engine.

May be my imagination but the truck turns over less and almost instantly starts like it used to.

REALLY appreciate all the hand holding on this!!!

 

[petersonj]

Nice job - you got right with the program.

Have you had a chance to drive the truck to observe how the torque converter lockup is behaving? If it is operating normally, it could be just because you had the batteries disconnected and the PCM / ECM are relearning the inputs. If this is the case, the symptoms could come back. If they do come back, you will just have to go further with inspecting / repairing other body ground connections. If the symptoms don't come back - then you have fixed it.

The exposed wire strands on the new battery connector are subject to corrosion over time. I would coat wires and connections with vaseline or a product of your choice.

- John

 

[Cummins12V98]

Have not driven but before starting I bent the ground wire up above the alternator and added a pc of aluminum tape. It did not act up after doing that.

One cable looked bad so I cut it back 1" and the copper looked good. YES I did add Di Electric grease to both negative wires.

 

[Cummins12V98]

Final touch adding 150A fuse. Added a mounting bracket to the battery tray.

STYLIN!!!

 

[petersonj]

Looks like a good location. Let us know in a few weeks or a few hundred miles of driving if your original symptoms are cured (the unwanted unlocking of the torque converter).

- John