Pinpoint Test I: The Tachometer Is Inoperative

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

Pinpoint Test I: The Tachometer Is Inoperative

Normal Operation

The Instrument Cluster (IC) receives the tachometer data from the PCM over the High Speed Controller Area Network (HS-CAN) communication bus and commands the tachometer according to the data. If the IC does not receive the engine rpm data or the data received is deemed invalid by the IC for more than 5 seconds, the IC sets DTC U0100.

NOTE: If DTC U0100 is set in the IC, other observable symptoms are likely to be an inoperative speedometer, tachometer and temperature gauge.

This pinpoint test is intended to diagnose the following:

- PCM
- IC

PINPOINT TEST I: THE TACHOMETER IS INOPERATIVE

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I1 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO SELF-TEST


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

Yes
DIAGNOSE all PCM DTCs first. REFER to Computers and Control Systems.

No
GO to I2.

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I2 CARRY OUT THE IC TACHOMETER ACTIVE COMMAND USING THE SCAN TOOL


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger .
- Select the IC tachometer (TACH_IND) active command and sweep the gauge in 10% increments.
- Does the tachometer start at 0 rpm and increase by 700 rpm for each 10% increase commanded?

Yes
GO to I3.

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

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I3 RETRIEVE THE RECORDED DTCs FROM THE IC SELF-TEST


- Check for recorded IC DTCs from the self-test.
- Is DTC U0100 recorded?

Yes
GO to Pinpoint Test AT. Pinpoint Test AT: DTC U0100

For DTC U2023, RETRIEVE and REPAIR all non-network DTCs in the PCM and other modules on the network. REFER to Computers and Control Systems and Multifunction Electronic Modules Diagnostic Trouble Code (DTC) Chart for a list of all DTCs.

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

No
INSTALL a new PCM. REFER to Electronic Engine Controls Service and Repair. TEST the system for normal operation.

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