Engine Speed Sensor, Checking: Notes
Function
The Engine Speed Sensor -G28- detects RPM and reference marks from a tooth wheel on the Crankshaft. 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.
Special tools and workshop equipment required
- Multimeter.
- Wiring Diagram.
- Scan Tool
Test requirements
- Fuses OK.
- Battery voltage OK
- Switch OFF all electrical consumers such as, lights and rear window defroster
- Vehicles with Automatic Transmission, ensure Selector Lever position is in "P".
- Vehicles with Manual Transmission, ensure Shifter Lever position is in "N" with Parking Brake applied.
- A/C OFF
- Ground connections between engine / transmission / chassis OK
- Coolant Temperature: ≥ 80 °C
- Observe all safety precautions: SAFETY PRECAUTIONS
- View clean working conditions: CLEAN WORKING CONDITIONS
Test procedure
-- PERFORM: preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK
-- CONNECT: Scan Tool
-- START: Engine
-- CHECK: Engine rpm:
| Diagnostic text | Specified value |
|---|---|
| Engine rotations per minute (rpm) | Cranking or idle speed |
-- IGNITION: OFF
If the specified value was obtained:
-- PERFORM: Visual Inspection of wiring and component
-- CHECK: wiring for an open, high resistance or short
-- CHECK: wiring connection for damage, corrosion, loose or broken terminals
-- REPAIR: faulty wiring or connection
-- GOTO: Final procedures Final procedures
If any of the specified value was not obtained:
-- DISCONNECT: Engine Speed Sensor -G28- electrical harness connector.
-- IGNITION: ON
-- CHECK: Engine Speed Sensor -G28- electrical harness connector terminals 1 to 3 for voltage.
Specified Value: About 5.0 V
-- IGNITION: OFF
Continue test according to the following table:
| Value | Cause | Test |
|---|---|---|
| If the specified value was not obtained: | Open or shorted circuit | GOTO: If the specified value was not obtained: |
| If the specified value was obtained: | Check reference signal circuit | GOTO: If the specified value was obtained: |