Checking Components
Check that the engine speed (RPM) sensor is correctly installed.
Check the engine speed (RPM) sensor connector. Check for intermittent contact resistance and oxidation.
The engine speed (RPM) sensor is sensitive to interference from surrounding power cables, the starter motor cable for example, or similar high amperage cables. This occurs when starting the engine for example.
Interference can cause difficulty in starting the engine, the engine does not start at all, the tachometer flickers at start attempts etc.
Causes of interference can be:
- surrounding power cables, for example an incorrectly routed starter motor cable
- incorrectly routed transmission bolted joints for the engine.
Checking the power cable
Check for incorrectly routed power cables (routed too close to the engine speed (RPM) sensor).
Checking the bolted joints
When removing and installing the transmission it is important that all the bolts for the engine are correctly tightened. Incorrectly tightened bolts can cause poor ground connection and interfere with the engine speed (RPM) sensor. Check that all the bolts from the transmission to the engine are correctly tightened.
Checking the wiring
Check the signal cable between the engine speed (RPM) sensor terminal #1 and engine control module (ECM) terminal #A48 (#A48) and between the engine speed (RPM) sensor terminal #2 and engine control module (ECM) terminal #A66 (#B6). Check for an intermittent short-circuit to supply voltage. Check for an intermittent short-circuit to ground. Check for an intermittent open-circuit.
Other information:
- see CHECKING WIRING AND TERMINALS
- For B5xx4T, see REPLACING THE ENGINE SPEED (RPM) SENSOR
- For B6xx4T, see ENGINE SPEED (RPM) SENSOR, REPLACING .
Remedy as necessary
- Continue
Refer to VERIFICATION