Allison 5sp: Allison troubleshooting

NSWelding

New member
May 19, 2018
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Hey guys. I just picked up a beautiful 2002 2500HD single cab duramax. Was an old man owned truck with 71,000 miles onit. The truck sat for three years without being driven or started. After replacing both batteries, fuel filter, engine oil and the twist on oil filter on the transmission, itruns.

I replaced the rear brake calipers, rotors and pads because they were sticking .

I have 3 engine codes that came up with my scan tool.

A quick description of the issues imhaving is the transmission frequently shifts gears. If I’m going 20-25 mph, the truck seems like it is stuck between upshifting and downshifting without accelerating or decelerating. Also the truck feels like it does not get up and go nearly as fast as it did when I first got it running. The transmission oil looks good and does not smell at all. I’ve googled the codes and I can’t seem to find any reasonable info on the problems.

The codes that came up are

P1631 main relay
P0700 transmission control system
U2106 throttle acuator control system - forced limited power

The last code I suspect is what’s going on with the shifting and power loss.

From what I have gathered on google I plan on installing a lift pump, 4” exhaust with a muffler, and some sort of gauges I really like the Edge CST insight one that does not alter powerbut monitors the engines vitals.

Can anyone shine some light on things I should check? Suggestions? Things I should get for the truck to increase mileage? I don’t particularly want to get a tuner that adds horsepower. The truck will be plenty good enough for hauling my 12,000 fishing boat. I like to leave my trucks somewhat stock to make them reliable.

Anyway thanks for any insight I appreciate it. Hope I can find some useful info on this forum

Ryan
 
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OregonDMAX

NOT IN OREGON, NO DURAMAX
Apr 28, 2013
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Goodyear, AZ
The p0700 is just telling you that there are more transmission code(s) and you need a scan tool that is capable of reading them.
 

NSWelding

New member
May 19, 2018
2
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The p0700 is just telling you that there are more transmission code(s) and you need a scan tool that is capable of reading them.

Thanks for the info. I’ll look for a different scan tool. The one I used was a diablosport tuner I had for my last 6.0 Silverado ..