Pinpoint Test J: Incorrect Tachometer Indication
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
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 does not receive the engine rpm data from the PCM for 5 seconds or less, the IPC defaults the tachometer to the last setting, based upon the last known good rpm message. If the IPC does not receive the engine rpm data from the PCM for more than 5 seconds, the IPC sets DTC U0100:00 in continuous memory and defaults the tachometer to 0 rpm.
NOTE: If DTC U0100:00 sets in the IPC, other observable symptoms may be an inoperative speedometer, temperature gauge or odometer.
This pinpoint test is intended to diagnose the following:
- PCM concern
- IPC
PINPOINT TEST J: INCORRECT TACHOMETER INDICATION
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J1 RETRIEVE THE RECORDED DTCs FROM PCM KOEO 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.
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J2 RETRIEVE THE RECORDED DTCs FROM THE IPC SELF-TEST
- Check for recorded IPC DTCs from the self-test.
- Are any DTCs recorded?
Yes
For DTC U0100:00, GO to Pinpoint Test AT Pinpoint Tests AT: DTC U0100:00. For all other DTCs, REFER to DTC Charts. Instrumentation, Message Center and Warning Chimes
No
GO to J3.
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J3 CARRY OUT THE TACHOMETER ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC DataLogger.
- Select the IPC 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. REFER to Instrument Panel Cluster (IPC) Instrument Panel Cluster (IPC). TEST the system for normal operation.
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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.
- Does the tachometer indication increase according to the above specifications?
Yes
The tachometer is operating correctly at this time.
No
INSTALL a new IPC. REFER to Instrument Panel Cluster (IPC) Instrument Panel Cluster (IPC). TEST the system for normal operation.
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