5000CD Quattro Wagon (Canada) L5-2226cc 2.22L SOHC Turbo (MC) (1986)
Engine Control Module: Component Tests and General Diagnostics
Tachometer Signal Test
Tachometer signal, checking
Work sequence
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Connect voltmeter between terminal 7 of control unit connector and ground
Note: This reading is made with connector attached to control unit. Gain access to terminals by pulling back connector boot
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Connect suitable tachometer to engine for measuring rpm
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Start engine and raise rpm to 2000
^
Specification: voltage increases as RPMs increase
If specification NOT OK
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Replace control unit
If voltage reading OK, but vehicle tachometer does not correspond with testing tachometer, check wire between terminal 7 of control unit connector and
vehicle tachometer according to current flow diagram. Repair as necessary.