Pinpoint Test I: Incorrect Tachometer Indication

Instrumentation and Warning Chimes

Pinpoint Test

Pinpoint Test I: Incorrect Tachometer Indication

Normal Operation

The tachometer indicates engine speed in revolutions per minute (rpm) ranging from 0 to 7,000 rpm. The engine speed data is sent from the PCM to the Instrument Cluster (IC) over the High Speed Controller Area Network (HS-CAN) communication bus. The IC, upon receipt of the engine speed signal, commands the tachometer pointer to the corresponding position. The IC sets DTC U0100 in continuous memory if the engine speed data is missing for more than 5 seconds or if invalid data is received and the tachometer indicates 0 rpm.

This pinpoint test is intended to diagnose the following:

- PCM concern
- IC



PINPOINT TEST I: INCORRECT TACHOMETER INDICATION

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I1 CARRY OUT THE IC GAUGES 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. Scroll the tachometer at 20%, 50% and 70%.
- Does the tachometer indicate approximately 1,400 rpm at 20%, 3,500 rpm at 50% and 4,900 rpm at 70%?

Yes
GO to I2.

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

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I2 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO SELF-TEST


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

Yes
REFER to Computers and Control Systems Information.

No
GO to I3.

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I3 RETRIEVE THE RECORDED DTCs FROM THE IC SELF-TEST


- Retrieve the recorded DTCs from the IC self-test.
- Is DTC U0100 retrieved?

Yes
GO to Pinpoint Test AK. Pinpoint Tests AK: DTC U0100

No
GO to I4.

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I4 MONITOR THE PCM ENGINE RPM SIGNAL PID


- Ignition ON.
- Start the engine.
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Select, monitor and record the PCM rpm PID (RPM) while accelerating the engine to different speeds.
- Compare the rpm PID values with the tachometer reading.
- Do the values on the tachometer match the PCM PID values?

Yes
The tachometer is operating correctly at this time.

No
INSTALL a new PCM. REFER to Computers and Control Systems. TEST the system for normal operation.

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