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 Cluster (IC) 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 invalid for 5 seconds or less or if the IC (Instrument Cluster) does not receive the engine rpm data for 5 seconds or less, the IC (Instrument Cluster) defaults the tachometer to the last setting, based upon the last known good rpm message. If the IC (Instrument Cluster) does not receive the engine rpm data from the PCM for more than 5 seconds, the IC (Instrument Cluster) sets DTC U0100 in continuous memory and defaults the tachometer to 0 rpm. If the engine rpm data is deemed invalid by the IC (Instrument Cluster) for 5 seconds or longer, the IC (Instrument Cluster) sets DTC U2023 and defaults the tachometer to 0 rpm.

NOTE: If DTC U0100 is set in the IC (Instrument Cluster), other observable symptoms may be an inoperative speedometer, temperature gauge or odometer.

This pinpoint test is intended to diagnose the following:

- PCM

- IC (Instrument Cluster)

PINPOINT TEST H : THE TACHOMETER IS INOPERATIVE

H1 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
DIAGNOSE all PCM DTCs first. REFER to the 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: IC (Instrument Cluster) DataLogger.

- Select the IC (Instrument Cluster) tachometer (TACH_IND) active command. Command the tachometer in 10% increments while monitoring the tachometer.

Does the tachometer begin at 0 rpm, increase to 7,000 rpm then return to 0 rpm?

Yes
GO to H3.

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

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

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

Are any DTCs recorded?

Yes
For DTC U0100, GO to Pinpoint Test AO. Pinpoint Test AO: DTC U0100

For DTC U2023, RETRIEVE and REPAIR all non-network DTCs in the PCM and other modules on the network. REFER to the Computers and Control Systems Information and Body Control Systems for a list of all DTCs.

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.