Pinpoint Test G: Incorrect Tachometer Indication

Instrumentation, Message Center and Warning Chimes

Pinpoint Test G: Incorrect Tachometer Indication

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) to command the tachometer.

The base (Edge only) and optional IPC (Instrument Panel Cluster) tachometers appear differently but function essentially the same. The base IPC (Instrument Panel Cluster) uses an analog gauge. The optional IPC (Instrument Panel Cluster) uses a digital display that provides a 6,000 rpm bar graph or a simulated 7,000 rpm analog gauge display depending on the display mode.

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 G : INCORRECT TACHOMETER INDICATION

G1 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 Information.

No
GO to G2.

G2 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 AQ Pinpoint Test AQ: DTC U0100:00.

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

No
GO to G3.

G3 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 600 rpm (optional IPC (Instrument Panel Cluster) bar graph display) or 700 rpm (base IPC (Instrument Panel Cluster) or IPC (Instrument Panel Cluster) analog gauge display) for each 10% increment?

Yes
GO to G4.

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

G4 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 944-1,056 at 1,000 rpm, 1,444-1,556 rpm at 1,500 rpm, 1,944-2,056 rpm at 2,000 rpm and 2,444-2,556 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) . TEST the system for normal operation.