Engine Speed Sensor - G28-, Checking

General Description

The Engine Speed Sensor -G28- Detects RPM And Reference Marks From A Toothed 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 and electronic accessories.
Vehicles with Auto. Transmission, ensure Selector Lever position is in "P".
Vehicles with Man. Transmission, ensure Shifter Lever position is in "N" with Parking Brake applied.
Observe all safety precautions: SAFETY PRECAUTIONS .
View clean working conditions: CLEAN WORKING CONDITIONS .

Test Procedure

Step	Procedure	Result / Action to Take
1	PERFORM: Preliminary Check to verify the customers complaint. Refer to PRELIMINARY CHECK . -- Was Complaint verified?	-- YES: GO TO: Step 2 Engine Speed Sensor - G28-, CHECKING - 2 . -- NO: GATHER more information from customer about the complaint.
2	CONNECT: Scan Tool. START or CRANK: Engine. CHECK: Engine RPM. SPECIFIED VALUE: Cranking or Idle RPM. IGNITION: OFF. -- Was Value obtained?	-- YES: GO TO: Step 3 Engine Speed Sensor - G28-, CHECKING - 3 . -- NO: GO TO: Step 4 Engine Speed Sensor - G28-, CHECKING - 4 .
3	CONDITION: May be intermittent. PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector.	GO TO: Step 7 Engine Speed Sensor - G28-, CHECKING - 7 .
4	DISCONNECT: Engine Speed Sensor -G28- harness connector. IGNITION: ON. CHECK: Engine Speed Sensor -G28- harness connector terminals 1 to 3 for voltage. SPECIFIED VALUE: About 5.0 V. IGNITION: OFF. -- Was Value obtained?	-- YES: GO TO: Step 5 Engine Speed Sensor - G28-, CHECKING - 5 . -- NO: GO TO: Step 6 Engine Speed Sensor - G28-, CHECKING - 6 .
5	REMOVE: Engine Control Module - J623-. Refer to the appropriate service information. CHECK: Engine Speed Sensor -G28- harness connector terminal 2 to the Engine Control Module - J623- harness connector T60 / 53 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Was Value obtained?	-- YES: CHECK: Engine Speed Sensor -G28- sensor wheel for proper seating, damage and/or run - out. Repair as required. Refer to the appropriate service information. REMOVE: Engine Speed Sensor -G28-. Refer to the appropriate service information. GO TO: Step 7 Engine Speed Sensor - G28-, CHECKING - 7 . Sensor wheel OK. REPLACE: Engine Speed Sensor -G28-. Refer to the appropriate service information. GO TO: Step 7 Engine Speed Sensor - G28-, CHECKING - 7 . -- NO: CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 7 Engine Speed Sensor - G28-, CHECKING - 7 .
6	REMOVE: Engine Control Module - J623-. Refer to the appropriate service information. CHECK: Engine Speed Sensor -G28- harness connector terminal 1 to the Engine Control Module - J623- harness connector T60 / 14 for resistance. CHECK: Engine Speed Sensor -G28- harness connector terminal 3 to the Engine Control Module - J623- harness connector T60 / 29 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: GO TO: Step 7 Engine Speed Sensor - G28-, CHECKING - 7 . -- NO: CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 7 Engine Speed Sensor - G28-, CHECKING - 7 .
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