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

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

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) (diesel engine) or from the PCM (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
- IC



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

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AD1 RETRIEVE AND RECORD THE IC DTCs FROM THE SELF-TEST


- Check for recorded IC DTCs from the self-test.
- Are any DTCs recorded?

Yes
For DTC U0100, GO to Pinpoint Test BD. Pinpoint Tests BD: DTC U0100

For DTC U0101, GO to Pinpoint Test BE. Pinpoint Tests BE: DTC U0101

For all other DTCs, REFER to DTC Charts. Instrumentation, Message Center and Warning Chimes

No
If equipped with gasoline engine, GO to AD2.

If equipped with diesel engine, GO to AD3.

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AD2 RETRIEVE AND RECORD THE DTCs FROM THE PCM KOEO SELF-TEST


- Check for recorded PCM DTCs from the Key ON Engine OFF (KOEO) self-test.
- Are any DTCs recorded?

Yes
REFER to Computers and Control Systems Information.

No
GO to AD4.

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AD3 RETRIEVE AND RECORD THE DTCs FROM THE TCM SELF-TEST


- Check for recorded TCM DTCs from the self-test.
- Are any DTCs recorded?

Yes
REFER to Automatic Transmission/Transaxle &/or Transmission Control Systems.

No
GO to AD4.

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AD4 CARRY OUT THE IC INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE SCAN TOOL


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger .
- Select the IC tow haul indicator (TOWHAUL_LMP) active command. Command the tow haul indicator on and off. Observe the tow haul indicator.
- Does the tow haul indicator illuminate when commanded on and turn off when commanded off?

Yes
If equipped with gasoline engine, INSTALL a new PCM. REFER to Computers and Control Systems. TEST the system for normal operation.

If equipped with diesel engine, INSTALL a new TCM. REFER to Automatic Transmission/Transaxle &/or Transmission Control Systems. TEST the system for normal operation.

No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.

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