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 Instrument Panel Cluster (IPC) the data over the High Speed Controller Area Network (HS-CAN) communication bus to command the tachometer according to the data.
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 is deemed invalid for 5 seconds or more, the IPC (Instrument Panel Cluster) sets DTC U0140:68 and defaults the tachometer to 0 rpm.
NOTE: If DTC U0100:00 is set 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 THE PCM KOEO (Key ON Engine OFF) SELF-TEST
- Check for recorded PCM DTCs from the Key ON Engine OFF (KOEO) self-test.
Are any DTCs recorded?
Yes
DIAGNOSE all PCM DTCs first. REFER to Computers and Control Systems Information.
No
GO to J2.
J2 RETRIEVE THE RECORDED DTCs FROM THE IPC (Instrument Panel Cluster) SELF-TEST
- Check for recorded DTCs from the IPC (Instrument Panel Cluster) 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 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 increments of 10% while monitoring the tachometer.
Does the tachometer increase approximately 700 rpm with 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 ENGINE RPM INPUT USING THE IPC (Instrument Panel Cluster) DEALER TEST MODE
- Ignition ON.
- Enter the IPC (Instrument Panel Cluster) dealer test mode.
- NOTE: The display below uses xxx's to represent a numeric or alpha-numeric value. The value may display the same amount of characters represented by the xxx's or there may be more/less depending on the type of display. For example: TACHOMETER xxx RPM may display TACHOMETER 650 RPM.
Scroll through the displays to TACHOMETER xxx RPM.
- Start the engine and operate the engine at 1,000, 1,500 and 2,000 rpm while monitoring both the tachometer and the engine rpm input in the dealer test mode.
Does the engine rpm input agree approximately with the position of the tachometer indication?
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.