I see several recommendations about removing splice 13 and R2. Where would these be located on one of these 8300-8500 trucks. Any harness labeling has long since disappeared on these lifts.

Many thanks for the info. I'll see what I can find out concerning the service bulletin.

From what I can tell it depends on what options the truck has. There's w/ power steering, then there's "premium" power steering. I'm showing a 1181995 for 'Harness, Potentiometer, Assembly' for power steering, and 2300445000 'Harness Assembly, Potentiometer' for Premium Power Steering. I would call in to your parts distributor with model/serial, as there's a service bulletin about replacing the carbon style pot with a solid state pot as well.

Thanks for the reply, unfortunately since my management team didn't reply in a timely manner I was forced to take a leap of faith. The steering pot was replaced along with running learn and so far the truck hasn't come back in. However, I have another truck that is starting to show the same symptoms so this will be a great help. I was aware of the two pots but don't know which our trucks use. Do you have the part numbers for each and are they interchangeable?

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Hopefully you got this figured out by now, but if not;
C81: Steer Unit Sum of Analog Inputs Out-of-Range
Reason: Wiring problem to steering sensor or failed sensor. Open or shorted R2 (carbon potentiometers only).
Tests to Run: 1. Run Learn on the steering.
2. Check wiring between pots and PSU. For trucks with a carbon potentiometer, the resistance of R2 should be 620 ohms.
3.Verify harness crimps are not missing or weak.
4. Verify pot voltages, V1 and V2, following the "pinout Matrix".
5. Verify correct version of software is in the VM, PSU, and TA.
6. Check for shorts to frame.

As for C91, that's missing from my manual as well for some reason. Not even in the contents.

C94: Steer Unit Sum of Analog Inputs Warning Threshold Exceeded
Reason: Wiring problem to steering sensor or steer sensor intermittent.
Tests to Run: 1. Run Learn on the steering.
2. Check wiring between pots and PSU. For trucks with a carbon potentiometer, the resistance of R2 should be 620 ohms.
3. Verify pot voltages, V1 and V2, following the "Pinout Matrix".
4. Verify correct version of software is in the VM and PSU.
5. Check for shorts to frame.

I would guess you have/had a wiring issue in the steerhead. I've had wires just pullout of connectors in these trucks before. Let us know if you got it solved.