Transmission Temp:

[stacks04]

if it was slipping while in lock up wouldn't the speed sensors pick it up? not quite sure how it is sensed while not in lock up as there is always some slip of the converter just by design, but during lock up it should detect slip even if it was the tcc. throwing the dreaded fifth gear out of range code. not quite sure just throwing it out there..

 

[MACKIN]

if it was slipping while in lock up wouldn't the speed sensors pick it up? not quite sure how it is sensed while not in lock up as there is always some slip of the converter just by design, but during lock up it should detect slip even if it was the tcc. throwing the dreaded fifth gear out of range code. not quite sure just throwing it out there..

I suppose IF there is a different set of values in the TCM as oppose to when NOT in Tow Haul verses in Tow Haul. AS the TC is locked normally ONLY in fifth gear. When in Tow Haul it locks after the first to second then in between shifts it locks and unlocks.

I would assume the speed sensor is more so monitoring input shaft and c1,but what do I know.

I know that if a clutch was slipping it would throw a code. The TC is the only thing I can think of that can possibly create that much heat do to slip and not throw a code. Barring clean filters and proper fluid level and no restrictions in flow.

I can only also suggest to check the transmission cooler for blockage of good air flow. The only other thing is to check actual pressure at lock up. Like I said just a slight slip will cause heat.