Pinpoint Test J: The Tachometer Is Inoperative

Instrumentation, Message Center and Warning Chimes

Pinpoint Test J: The Tachometer Is Inoperative

Normal Operation

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

If the IPC (Instrument Panel Cluster) does not receive the engine rpm data from the PCM for 5 seconds or less, the IPC (Instrument Panel Cluster) defaults the tachometer to the last setting, based upon the last known good rpm message. If the IPC (Instrument Panel Cluster) does not receive the engine rpm data from the PCM for more than 5 seconds, the IPC (Instrument Panel Cluster) sets DTC U0100:00 in continuous memory and defaults the tachometer to 0 rpm.

NOTE: If DTC U0100:00 sets in the IPC (Instrument Panel Cluster), other observable symptoms may be an inoperative speedometer, temperature gauge or odometer.

This pinpoint test is intended to diagnose the following:

- PCM

- IPC (Instrument Panel Cluster)

PINPOINT TEST J : THE TACHOMETER IS INOPERATIVE

J1 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO (Key ON Engine OFF) 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. TEST the system for normal operation.

No
GO to J2.

J2 CARRY OUT THE TACHOMETER ACTIVE COMMAND USING THE SCAN TOOL

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: IPC (Instrument Panel Cluster) DataLogger.

- Select the IPC (Instrument Panel Cluster) tachometer (TACH_IND) active command. Command the tachometer on and off while monitoring the tachometer.

Does the tachometer begin at 0 rpm, increase to 5,000 rpm (diesel) or 7,000 rpm (gas) then return to 0 rpm?

Yes
GO to J3.

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

J3 RETRIEVE THE RECORDED DTCs FROM THE IPC (Instrument Panel Cluster) SELF-TEST

- Check for recorded IPC (Instrument Panel Cluster) DTCs from the self-test.

Are any DTCs recorded?

Yes
For DTC U0100:00, GO to Pinpoint Test BA. Pinpoint Test BA: DTC U0100:00

For all other DTCs, REFER to DTC Charts. Instrumentation, Message Center and Warning Chimes
No
INSTALL a new PCM. TEST the system for normal operation.