Pinpoint Test V: The Overdrive (O/D) Off/Tow Haul Indicator Is Never/Always On

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

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

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V1 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 AP (4R70E/4R75E transmission). Pinpoint Tests AP: DTC U0100

For DTC U0101, GO to Pinpoint Test AQ (6R80 transmission). Pinpoint Tests AQ: DTC U0101

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

No
GO to V2.

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V2 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.

No
GO to V3.

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V3 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 (OVERDRV) 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
For 4R70E/4R75E transmission, INSTALL a new PCM. REFER to Computers and Control Systems. TEST the system for normal operation.

For 6R80 transmission, INSTALL a new TCM. REFER to Automatic Transmission/Transaxle &/or Transmission Control Systems (mechatronic assembly).

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

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