Test L: Incorrect Tachometer Indication

PINPOINT TEST L: INCORRECT TACHOMETER INDICATION

Normal Operation
The PCM uses the crankshaft position 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 instrument cluster (IC) does not receive the engine rpm data from the PCM for 5 seconds or less, the instrument cluster (IC) defaults the tachometer to the last setting, based upon the last known good rpm message. If the instrument cluster (IC) does not receive the engine rpm data from the PCM for more than 5 seconds, the instrument cluster (IC) sets DTC U0100 in continuous memory and defaults the tachometer to 0 rpm. If the engine rpm data is deemed invalid by the instrument cluster (IC), the instrument cluster (IC) sets DTC U2023 and defaults the tachometer to 0 rpm.

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

This pinpoint test is intended to diagnose the following:
- PCM concern
- Instrument cluster (IC)

L1-L5:

L6: