Fault diagnosis, tachometer (rev counter) (MIU1)

Fault diagnosis, tachometer (rev counter) (MIU1)

Does the fuel gauge work?

yes

Continue with point 2

no

Rectify the power supply

2. Check the rpm signal

-	Unplug main instrument unit connector 12p- 1. Connect the ISAT scan tool test cable to pin 4 and a good ground.

-	Select “TEST” and then “PULSE”.

-	Start the engine.

The ISAT scan tool should show about 30 Hz at idling speed. Is this reading obtained?

yes

Change the main instrument display panel and continue with point 3.

no

Check the lead between pin 6 of the MOTRONIC control module and pin 4 of the main instrument display panel's 12p-1 connector. Rectify as necessary and then continue with point 3.

3. Final check

Functionality OK?

yes

The steps taken to rectify the fault were correct.

no

Continue fault diagnosis as described in "Service Manual 2:7 MOTRONIC 2.10".