Test requirements
The Motronic Engine Control Module (ECM) - J220- fuses OK.
Battery voltage at least 12.5 volts.
All electrical consumers such as, lights and rear window defroster, switched off.
Vehicles with automatic transmission, shift selector lever into position “P” or “N”.
A/C switched off.
Ground (GND) connections between engine/transmission/chassis OK.
Ignition switched off.
Start diagnosis
The Engine Speed (RPM) Sensor -G28- detects RPM and reference marks. Without an engine speed signal, the engine will not start. If the engine speed signal fails while the engine is running, the engine will stop immediately.
Function test
Connect the scan tool.
Switch the ignition on.
Using the scan tool, check the engine speed:
Diagnostic text -------------------------- Specified value
Engine rotations per minute (RPM) --- Idle speed
End diagnosis and switch ignition off.
If the specified value was not obtained:
Checking internal resistance
Disconnect the gray Engine Speed (RPM) Sensor -G28- electrical harness connector -arrow-.
Using a multimeter, check the Engine Speed (RPM) Sensor -G28- terminals 2 to 3 -see insert- for resistance
Specified value: 480 to 1000 Ω (at approx. 20° C)
– Check Engine Speed (RPM) Sensor -G28- terminals 1 to 2 and 1 to 3 for short circuits.
Specified value: ∞ (infinity)
If any of the specified values are not obtained:
Replace the Engine Speed (RPM) Sensor -G28-
