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.
The non-hybrid and hybrid tachometers appear differently but function essentially the same. The non-hybrid gauge is an analog gauge with a needle that points to a specified area of the gauge depending on the data received from the PCM. The hybrid gauge is a digital display that provides a bar, which indicates engine rpm when the gas engine is running. When the vehicle transitions into electric vehicle mode, the EV gauge replaces the tachometer. The hybrid tachometer is only displayed in the enlighten display mode.
The hybrid requires two messages sent from the PCM to operate the tachometer. The first message is an engine active message indicating that the vehicle is in the gas engine operating mode. The second message required for the tachometer is the actual engine rpm data.
If the engine rpm data is invalid for 5 seconds or less or if the IPC does not receive the engine rpm data 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. If the engine rpm data is deemed invalid by the IPC for 5 seconds or more, the IPC sets DTC U0401:68 and defaults the tachometer to 0 rpm.
NOTE: If DTC U0100:00 is set 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 CARRY OUT THE TACHOMETER ACTIVE COMMAND USING THE SCAN TOOL
NOTE: On hybrid vehicles, verify that the IPC display mode is set to the enlighten mode setting before beginning diagnostics.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC DataLogger .
- Start the engine.
- NOTE: On hybrid, make sure to set the scan tool to 0 rpm before beginning this test.
- Select the IPC tachometer (TACH_IND) active command. Command the tachometer according to the following table while monitoring the tachometer.
- Does the tachometer indicate the approximate rpm according to the above specification?
Yes
GO to J2.
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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J2 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO 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 J3.
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J3 RETRIEVE THE RECORDED DTCs FROM THE IPC SELF-TEST
- Check for recorded DTCs from the IPC self-test.
- Are any DTCs recorded?
Yes
For DTC U0100:00, GO to Pinpoint Test BF. Pinpoint Tests BF: DTC U0100:00
For DTC U0401:68, RETRIEVE and REPAIR all non-network DTCs in the PCM and other modules on the network. REFER to Computers and Control Systems Information and Multifunction Electronic Modules Testing and Inspection for a list of all DTCs.
For all other DTCs, REFER to DTC Charts. Instrumentation, Message Center and Warning Chimes
No
GO to J4.
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J4 CHECK THE ENGINE RPM INPUT USING THE IPC DEALER TEST MODE
- Ignition ON.
- Enter the IPC 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 (non-hybrid) or Tachometer x rpm (hybrid) may display TACHOMETER 650 RPM (non-hybrid) or Tachometer 650 rpm (hybrid).
- Scroll through the displays to TACHOMETER xxx RPM (non-hybrid) or Tachometer x rpm (hybrid).
- 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. REFER to Instrument Panel Cluster (IPC) Instrument Panel Cluster (IPC). TEST the system for normal operation.
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