Manifold Absolute Pressure Sensor -G71-, Checking

General Description

The ECM uses the Manifold Absolute Pressure Sensor -G71- signal to calculate a correction value for the charge air pressure and temperature. Evaluation of the signal gives consideration to the influence of temperature on the density of the charge air.

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. -- NO: GATHER more information from customer about the complaint.
2	DISCONNECT: Manifold Absolute Pressure Sensor -G71- harness connector. IGNITION: ON. CHECK: Manifold Absolute Pressure Sensor -G71- harness connector terminals 1 to 3 for voltage. IGNITION: OFF. SPECIFIED VALUE: About 5.0 V. -- Was Value obtained?	-- YES: GO TO: Step 3. -- NO: GO TO: Step 4.
3	REMOVE: Engine Control Module - J623-. Refer to appropriate Service Information. CHECK: Manifold Absolute Pressure Sensor -G71- harness connector terminal 2 to the Engine Control Module - J623- harness connector T105 / 77 for resistance. CHECK: Manifold Absolute Pressure Sensor -G71- harness connector terminal 4 to the Engine Control Module - J623- harness connector T105 / 76 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Was Value obtained?	-- YES: REPLACE: Manifold Absolute Pressure Sensor -G71-. Refer to appropriate Service Information. GO TO: Step 5. -- NO: 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 5.
4	REMOVE: Engine Control Module - J623-. Refer to appropriate Service Information. CHECK: Manifold Absolute Pressure Sensor -G71- harness connector terminal 1 to the Engine Control Module - J623- harness connector T105 / 97 for resistance. CHECK: Manifold Absolute Pressure Sensor -G71- harness connector terminal 3 to the Engine Control Module - J623- harness connector T105 / 98 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: GO TO: Step 5. -- NO: 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 5.
5	Final Procedure Perform a road test to verify repair. -- Does the original DTC return?	-- YES: CHECK: Engine Control Module -J623- harness connector for any damaged, pushed-out pins. REPAIR: As necessary. If all electrical connections are OK: REPLACE: Engine Control Module -J623-. Refer to appropriate Service Information. Clear the DTC's. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY . Repair is complete. Generate Readiness Code. Refer to READINESS CODE . Return vehicle to Customer. -- NO: Perform the diagnostic procedure for any DTC's. If no DTC's return the repair is complete. Return vehicle to customer.