Pinpoint Test D: The Tachometer Is Inoperative

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

Pinpoint Test D: The Tachometer Is Inoperative

Normal Operation

The tachometer is electrically operated and indicates the engine speed in rpm. The tachometer range is 0 to 7,000 rpm. The PCM uses the Crankshaft Position (CKP) sensor to measure the engine rpm and sends the data to the Instrument Cluster (IC), over the High Speed Controller Area Network (HS-CAN), to command the tachometer gauge. If the rpm information sent to the IC is invalid or missing, the IC defaults the tachometer to 0 rpm.

This pinpoint test is intended to diagnose the following:

- PCM
- IC

PINPOINT TEST D: THE TACHOMETER IS INOPERATIVE

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D1 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO SELF-TEST


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

Yes
REFER to Computers and Control Systems.

No
GO to D2.

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D2 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) active command and command the tachometer to 1,400, 2,800, 4,200, 5,600, and 7,000 rpm.
- Does the tachometer gauge move to the commanded rpms?

Yes
INSTALL a new PCM. REFER to Electronic Engine Controls Service and Repair. 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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