Tests AD: The Tow Haul Indicator Is Never/Always On

PINPOINT TEST AD: THE TOW HAUL INDICATOR IS NEVER/ALWAYS ON

Normal Operation
The tow haul indicator illuminates when the tow haul system has been engaged and is actively providing tow haul control for the vehicle. The instrument cluster (IC) receives the tow haul status from the transmission control module (TCM) when equipped with a diesel engine or from the PCM when equipped with a gasoline engine 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.

This pinpoint test is intended to diagnose the following:
- PCM
- TCM
- Instrument cluster (IC)

AD1-AD2:

AD3-AD7: