PID 120 Multiplier & Offset

I have a 2000 Foretravel U-320 with the Allison Retarder. I added the retarder temp guage and it seems to work fine with one major exception: the numbers are low. Example: After being parked for two days I made the following reading in the morning: Outside temp: 57, tranny temp: 59, retarder temp 29. I would expect them to be about the same. Another reading cruising on the level without recent use of the retarder: Tranny temp: 170, Retarder temp: 109. When using the retarder the temps rise and fall as expected.

I've plotted all my readings and find that if I use a multiplier of 1.5 and an offset of 16. My corrected values are reasonably close to the expected values.

Is it reasonable to have to use these values for the multiplier and offset?

re: offsets and multipliers on temperatures.

Hello Nelson

This is the first I've heard of someone having to do maths to work out this temperature. Following your schema, it would seem likely the type sensor used is not outputing data according to the expected SAE norm or is the wrong one.

If it seems pretty linear, could it be the wrong sensor? That would explain why our factoring is off on your coach but not any others. Not sure yet its an exception to the rule, something unique to your coach. Call it an "Undocumented Feature."

cheers ;-)