Pinpoint Test D: Incorrect Tachometer Indication

Instrumentation, Message Center and Warning Chimes

Pinpoint Test D: Incorrect Tachometer Indication

Normal Operation

If the engine rpm data is 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.

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 received is deemed invalid by the IPC (Instrument Panel Cluster) for 5 seconds or more, the IPC (Instrument Panel Cluster) sets DTC U0401:68 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 or odometer.

This pinpoint test is intended to diagnose the following:

- PCM concern

- IPC (Instrument Panel Cluster)

PINPOINT TEST D : INCORRECT TACHOMETER INDICATION

D1 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.

No
GO to D2.

D2 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 AM Pinpoint Test AM: DTC U0100:00 and P1607:87.

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

No
GO to D3.

D3 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 in increments of 10% while monitoring the tachometer. The rpm indicated should increase in increments of approximately 700 rpm for each 10% change.

Does the tachometer indication increase within specifications?

Yes
GO to D4.

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

D4 CHECK THE PCM RPM PIDs

- Enter the following diagnostic mode on the scan tool: PCM DataLogger.

- Select the PCM engine rpm (RPM) PID and monitor the tachometer while operating the engine at 1,000, 1,500, 2,000 and 2,500 rpm using the PCM PID to set the vehicle speed.

Does the tachometer indication range between 922-1,078 at 1,000 rpm, 1,422-1,578 rpm at 1,500 rpm, 1,922-2,078 rpm at 2,000 rpm and 2,422-2,578 rpm at 2,500 rpm?

Yes
The tachometer is operating correctly at this time.

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