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 PCM uses the Crankshaft Position (CKP) sensor to measure the engine rpm. The PCM sends the Instrument Cluster (IC) the engine rpm data over the High Speed Controller Area Network (HS-CAN) communication bus to command the tachometer according to the data.

If the engine rpm data is missing or invalid for 5 seconds or less, the IC defaults the tachometer to the last setting, based upon the last known good rpm message. If the IC does not receive the engine rpm data from the PCM for more than 5 seconds, the IC sets DTC U0101 in continuous memory and defaults the tachometer to 0 rpm. If the engine rpm data is deemed invalid by the IC for 5 seconds or longer, the IC defaults the tachometer to 0 rpm.

NOTE: If DTC U0101 is set in the IC, other observable symptoms may be an inoperative speedometer, temperature gauge or odometer.

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 the 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 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 U0101, GO to Pinpoint Test AM. Pinpoint Tests AM: DTC U0101

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 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. Command the tachometer on then off while monitoring the tachometer.
- Does the tachometer begin at 0 rpm, increase to 7,000 rpm then return to 0 rpm?

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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