Pinpoint Test V: The Overdrive (O/D) Off/Tow Haul Indicator Is Never/Always On
Instrumentation, Message Center and Warning Chimes
Pinpoint Test V: The Overdrive (O/D) Off/Tow Haul Indicator Is Never/Always On
Normal Operation
The Overdrive (O/D) off/tow haul indicator illuminates when the O/D function is turned off or the tow haul system has been engaged and is actively providing tow haul control for the vehicle. The Instrument Cluster (IC) receives the O/D off/tow haul status from the Transmission Control Module (TCM) (6R80 transmission) or from the PCM (4R70E/4R75E transmission) over the High Speed Controller Area Network (HS-CAN) communication bus. When the vehicle is in tow haul mode, the transmission does not shift into overdrive and the vehicle may also provide engine braking and early transmission downshifts when braking on downhill grades.
If the O/D off/tow haul message is missing for less than 5 seconds, the O/D off/tow haul indicator remains in the last on/off state, based upon the last good known O/D off/tow haul message received.
If the O/D off/tow haul message is missing for more than 5 seconds, the sets DTC U0101 in continuous memory and defaults the O/D off/tow haul indicator off.
This pinpoint test is intended to diagnose the following:
- PCM (4R70E/4R75E transmission)
- TCM (6R80 transmission)
- IC
PINPOINT TEST V: THE O/D OFF/TOW HAUL INDICATOR IS NEVER/ALWAYS ON
