Tachometer Out Of Order

OUTPUT SIGNAL TO MAIN INSTRUMENT DISPLAY PANEL





Symptom Of Fault.
Tachometer does not work.





Diagnostic Procedure.
1. Check The Wiring.
- Check The Wiring between pin 58 of the Trionic control module and pin 2 of the tachometer for continuity.
- Check the lead for open circuit and shorting.

Is the lead OK?
YES:
^ Continue with point 2.
NO:
^ Rectify the fault.

2. Check the output signal
- Plug in the Trionic control module.
- Unplug the main instrument display panel's connector.
- Start the engine and run it at idling speed.
- Take a frequency reading across pins 2 and 6. of the connector.
At idling speed, about 850 rpm, the frequency should be about 28 Hz.

Is the reading OK?
YES:
^ Continue fault diagnosis in the Electrical system, main instrument display panel.
NO:
^ Proceed at "Before Replacing a Control Module". Component Tests and General Diagnostics