Pinpoint Test E: The Tachometer Is Inoperative

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

Pinpoint Test E: The Tachometer Is Inoperative

Normal Operation

The tachometer is electrically operated and indicates the engine speed in revolutions per minute (rpm). The tachometer range is 0 to 7,000 rpm. The PCM uses the Crankshaft Position (CKP) sensor to measure the engine rpm. The PCM sends the engine rpm 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 E: THE TACHOMETER IS INOPERATIVE

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E1 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO SELF-TEST


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

Yes
REFER to Computers and Control Systems Information.

No
GO to E2.

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E2 RETRIEVE THE RECORDED DTCs FROM THE IC SELF-TEST


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

Yes
For DTC U1900, REFER to Information Bus.

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

No
GO to E3.

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E3 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. Command the tachometer on and off. Observe the tachometer.
- Does the tachometer start at 0 rpm and move to 7,000 rpms when commanded on, and return to 0 when commanded off?

Yes
INSTALL a new PCM. REFER to Computers and 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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