Fault diagnosis, tachometer (rev counter)(MIU1)
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Fault diagnosis, tachometer (rev counter)
(MIU1)
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Fault symptoms
Tachometer inoperative.
Diagnostic procedure
1. Check the power supply
Does the fuel gauge work?
Continue with point 2
Rectify the power supply
2. Check the rpm signal
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Unplug main instrument display panel connector 12p-
1.
Connect the ISAT scan tool test cable to pin 4 and a good ground.
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Select “TEST” and then “PULSE”.
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The ISAT scan tool should show about 30 Hz at idling speed. Is this reading
obtained?
Change the main instrument display panel and continue with point 3.
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?
The steps taken to rectify the fault were correct.
Continue fault diagnosis as described in "Service Manual 2:7 MOTRONIC
2.10".