Pinpoint Test H: The Tachometer Is Inoperative

Instrumentation, Message Center and Warning Chimes

Pinpoint Test H: 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 gauge according to the data.

If the engine rpm data is missing or invalid for 5 seconds or less or if the IPC (Instrument Panel Cluster) does not receive the engine rpm data 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 received.

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.

If the engine rpm data is deemed invalid by the IPC (Instrument Panel Cluster) for 5 seconds or more, the IPC (Instrument Panel Cluster) sets DTC U0401:29 and defaults the tachometer to 0 rpm.

NOTE: If DTC U0100:00 is set 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 H : THE TACHOMETER IS INOPERATIVE

H1 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO (Key ON Engine OFF) SELF-TEST

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

Are any DTCs recorded?

Yes
DIAGNOSE all PCM DTCs first. REFER to Computers and Control Systems Information.

No
GO to H2.

H2 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) mode active command. Command the tachometer on and off.

Does the tachometer begin at 0 rpm, increase to 6,000 rpm then return to 0 rpm?

Yes
GO to H3.

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

H3 RETRIEVE THE RECORDED DTCs FROM THE IPC (Instrument Panel Cluster) SELF-TEST

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

Are any DTCs recorded?

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