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C8.3 Throttle Position Sensor

November 25, 2019, 12:42:12 pm

I have been troubleshooting a retarder problem (retarder light does not come on and the retarder does not actuate). The Allison manual points to the TPS in its troubleshooting tree as a possible cause, but having read many threads I cannot find one on my engine. Many of the threads referred to 2 cables coming off the throttle control, but mine only has one (from the King controller). Wondering how the transmission knows when to shift since it does not have a vacuum input like the older gas engines had. Anyone have any experience with this?  Thanks, Ed

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Re: C8.3 Throttle Position Sensor

Reply #1 – November 25, 2019, 01:53:26 pm

I don't know where your TPS is located, or even if your engine has one.  Perhaps the Allison gets TPS input from the King controller?

On our '93 model, the TPS is mounted to the frame on the curb side of the engine compartment.  On our engine there are two cables attached to the bracket holding the throttle control linkage.  One cable goes to the TPS - other to the Bendix cruise control.  Link to post below with a photo of the TPS doohickie on our coach.

Allison MD3060R throttle position sensor location

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Re: C8.3 Throttle Position Sensor

Reply #2 – November 25, 2019, 02:59:11 pm

Thanks Chuck, mine does not appear to have one. Trying to decipher what drwgs I have to figure out how the circuits function.

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