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John, Master A.S.E Automotive technician
Category: Chevy
Satisfied Customers: 9176
Experience:  A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
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I have a 2004 Workhorse motorhome chassis with the 8.1 GM engine.

Customer Question

I have a 2004 Workhorse motorhome chassis with the 8.1 GM engine.
Twice it has shutdown to reduced power. On both occasions, shutting the engine off and restarting 3 times cleared the problem, but the check engine light was on. On the scan tool the following code was displayed: P2101 Mode $ 10, TAC, Motor, CKT Range/Perf. Two additional cycles of the starter to off and back to on cleared the problem. Both times, the outside temp was about 60 degrees, the engine and transmission were at normal temp, and the engine load was about 50 percent, pulling a slight grade. I checked all connections and wires and all seems to be ok. Any suggestions? Thanks for your help.
Submitted: 6 years ago.
Category: Chevy
Expert:  John replied 6 years ago.

Hello & Welcome to JA,


If you would give me the VIN # XXXXX identify the platform this vehicle is built on,I believe I can help you.

Customer: replied 6 years ago.

The vin # XXXXX XXXXX Thanks for your help.

Expert:  John replied 6 years ago.

Ok, if I understand you correctly, the Electronic throttle actuator control module , throttle body assembly have been replaced.

This problem I see a lot of harnesses about a foot or two from the throttle body with broken wiring which causes an intermitten condition. These are low voltage circuits & it does not take much to add a small amount of resistance which will give the PCM an incorrect reading of commanded & actual position of the throttle. I suggest you ohm the wires from the PCM,to the TAC to the APP. Here is a schematic to help .


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Customer: replied 6 years ago.
I have not replaced anything yet. I didn't want to just throw parts at it until I had a good idea where to go first. Thanks for your help. I'll check those wires.
Expert:  John replied 6 years ago.
Ok ,if the wiring is not the problem the parts that fails the most is the sensors in the throttle body assembly. Hope you have a good evening.