Pinpoint Test I: Incorrect Tachometer Indication
Instrumentation, Message Center and Warning Chimes
Pinpoint Test I: Incorrect Tachometer Indication
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 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 concern
- IC (Instrument Cluster)
PINPOINT TEST I : INCORRECT TACHOMETER INDICATION
I1 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 I2.
I2 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
GO to I3.
I3 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 increments of 10% while monitoring the tachometer.
Does the tachometer indication increase within specifications?
Yes
GO to I4.
No
INSTALL a new IC (Instrument Cluster). REFER to Instrument Cluster (IC) . TEST the system for normal operation.
I4 CHECK THE ENGINE RPM INPUT USING THE IC (Instrument Cluster) DEALER TEST MODE
- Ignition ON.
- Enter the IC (Instrument 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 with the position of the tachometer indication?
Yes
The tachometer is operating correctly at this time.
No
INSTALL a new IC (Instrument Cluster). REFER to Instrument Cluster (IC) . TEST the system for normal operation.