Pinpoint Test J: Incorrect Tachometer Indication

Instrumentation, Message Center and Warning Chimes

Pinpoint Test J: Incorrect Tachometer Indication

Normal Operation

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

- IPC (Instrument Panel Cluster)

PINPOINT TEST J : INCORRECT TACHOMETER INDICATION

J1 RETRIEVE THE RECORDED DTCs FROM 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. TEST the system for normal operation.
No
GO to J2.

J2 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 AT. Pinpoint Test AT: DTC U0100:00

For all other DTCs, REFER to DTC Charts. Instrumentation, Message Center and Warning Chimes
No
GO to J3.

J3 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 10% increments while monitoring the tachometer.

Does the tachometer indication increase by 700 rpm at each 10% increment?

Yes
GO to J4.
No
INSTALL a new IPC (Instrument Panel Cluster). REFER to Instrument Panel Cluster (IPC) . TEST the system for normal operation.

J4 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.

Command Indication Range 1,000 rpm 922-1,078 rpm 1,500 rpm 1,422-1,578 rpm 2,000 rpm 1,922-2,078 rpm 2,500 rpm 2,422-2,578 rpm



Does the tachometer indication increase according to the above specifications?

Yes
The tachometer is operating correctly at this time.
No
INSTALL a new IPC (Instrument Panel Cluster). REFER to Instrument Panel Cluster (IPC) . TEST the system for normal operation.