Pinpoint Test M: Incorrect Tachometer Indication
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test M: 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) the data over the High Speed Controller Area Network (HS-CAN) communication bus to command the tachometer gauge according to the data.
If the IC does not receive the engine rpm data from the PCM for 5 seconds or less, the IC defaults the tachometer to the last setting, based upon the last known good rpm message. If the IC does not receive the engine rpm data from the PCM for more than 5 seconds, the IC sets DTC U0100 in continuous memory and defaults the tachometer to 0 rpm. If the engine rpm data is deemed invalid by the IC, the IC sets DTC U2023 and defaults the tachometer to 0 rpm.
NOTE: If DTC U0100 is set in the IC, other observable symptoms may be an inoperative speedometer, temperature gauge or odometer.
This pinpoint test is intended to diagnose the following:
- IC
PINPOINT TEST M: INCORRECT TACHOMETER INDICATION
-------------------------------------------------
M1 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 Information.
No
GO to M2.
-------------------------------------------------
M2 RETRIEVE THE RECORDED DTCs FROM THE IC SELF-TEST
- Check for recorded IC DTCs from the self-test.
- Are any DTCs recorded?
Yes
For DTC U0100, GO to Pinpoint Test BD. Pinpoint Tests BD: DTC U0100
For all other DTCs, REFER to DTC Charts. Instrumentation, Message Center and Warning Chimes
No
GO to M3.
-------------------------------------------------
M3 CARRY OUT THE TACHOMETER ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger .
- Select the IC tachometer (TACH) active command. Command the tachometer to 700, 1,400, 2,100, 2,800, 3,500, 4,200 and 4,900 rpm while monitoring the tachometer.
- Does the tachometer indication increase within specifications?
Yes
GO to M4.
No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
-------------------------------------------------
M4 CHECK THE ENGINE RPM INPUT USING THE IC DEALER TEST MODE
NOTE: After exiting a dealer test mode session, it is necessary to clear all IC DTCs. Carry out the IC self-test.
- Ignition ON.
- Enter the IC 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. TEST the system for normal operation.
No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
-------------------------------------------------