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Pete, Technician
Category: Car
Satisfied Customers: 27813
Experience:  17 years automotive training and experience.
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GM National RV Dolphin: I have a 2005 National RV Dolphin with

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I have a 2005 National RV Dolphin with a Workhorse Chassis. 8.1 Vortec engine and Allison Transmission. On several occasions it has suddenly shut down to a safe mode and given a check engine code of U0107, meaning lost communication with throttle control actuator. After resetting to check engine light, everything works a normal. This only seems to happen about every 1,000 to 2,000 miles and the last 3 times occurred while I was setting the cruise control. I have had it in to the Workhorse shop numerous times for this problem and they have had no luck identifying and fixing the problem. Where do I go from here?
My name is XXXXX XXXXX I am a professional here at Just Answer. I noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

The loss communication with the throttle actuator can be a common fault.In most cases this is an intermittent fault with the throttle actuator itself (usually part of the throttle body itself) and had to be replaced to correct this here.

I would have the throttle actuator wiring checked to make sure there is no wiring damage as well as the electrical connection is tight at the actuator.You might try and wiggle the wiring harness at the throttle actuator and leading off of it to see if the vehicle acts up when this is done.If it does act up this indicates a fault in the wiring and the wiring needs checked further to locate a short in it and then repaired.

If no faults are found with the wiring and with the common fault I have seen before in some cases this sounds to be an internal electrical fault in the throttle actuator itself.This can be very difficult to identify as the fault with the intermittent issue like this,I have ran into this several times before.

Let me know if you need anything else,thanks Pete.
Customer: replied 3 years ago.

The wiring has been checked several times. Everything on you list has been checked except the throttle body has not been replaced. The unusual link here is the cruise control. Why does it only seem to be activated when the cruise control is being set? There is another issue with the dash cluster where on very rare occasions when I go over a very noticeable bump the dash cluster will shut down momentarily and then restart, but, the engine does not stall and no check engine lights come on. I had the dash cluster replaced about 2 years ago. It did this before the dash cluster was replaced as well.


This may still be a fault with the throttle body itself as I have seen these fail and the cruise is tied into the electronic throttle body and if the computer is trying to activate the cruise and sees a fault when activating it will cause this or if the throttle body has some degree of voltage differences in it or communication issues when the cruise is being set this will cause this as well.

As for the cluster issues if this occurs going over bumps this sounds like a loose connection either at the cluster itself or one of the voltage or ground signals to the cluster are at fault causing this.Unfortunately my info doesn't list a diagram on this vehicle to tell you what grounds or voltages to check but this does sound like a loose connection.This loose connection may also be involved with the throttle issue.

Thanks Pete
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I am following up with you to see if you still needed help with your question you had asked.If my help didn't satisfy your question please let me know so we can continue.

Thanks Pete