Charge Air Pressure Sensor - G31-, CHECKING

General Description

The air mass and charge pressure are two factors used for engine load management. For this purpose, there are several sensors with absolutely identical functions. They measure the intake air temperature and the intake manifold pressure. The first sender unit is located upstream of the Throttle Valve Control Module -J338/GX3- in the Charge Air Pressure Sensor -G31-. They measure the pressure and temperature of the air in each individual cylinder bank. The values measured here correspond to the actual air mass in the cylinder bank(s).

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 automatic transmission, ensure the selector lever position is in "P".
Vehicles with manual transmission, ensure the shifter lever position is in "N" with the 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 Charge Air Pressure Sensor - G31-, CHECKING => 2 . -- NO: GATHER more information from customer about the complaint.
2	IGNITION: OFF. DISCONNECT: Charge Air Pressure Sensor -G31- harness connector. IGNITION: ON. CHECK: Charge Air Pressure Sensor -G31- harness connector terminals 1 to 3 for voltage. IGNITION: OFF. SPECIFIED VALUE: About 5.0 V. -- Was Value obtained?	-- YES: GO TO: Step 3 Charge Air Pressure Sensor - G31-, CHECKING => 3 . -- NO: GO TO: Step 4 Charge Air Pressure Sensor - G31-, CHECKING => 4 .
3	REMOVE: Engine/Motor Control Module - J623-. Refer to appropriate service information. CHECK: Charge Air Pressure Sensor -G31- harness connector terminal 2 to the Engine/Motor Control Module - J623- harness connector T91 / 54 for resistance. CHECK: Charge Air Pressure Sensor -G31- harness connector terminal 4 to the Engine/Motor Control Module - J623- harness connector T91 / 55 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: REPLACE: Charge Air Pressure Sensor -G31-. Refer to appropriate service information. GO TO: Step 5 Charge Air Pressure Sensor - G31-, CHECKING => 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 Charge Air Pressure Sensor - G31-, CHECKING => 5 .
4	REMOVE: Engine/Motor Control Module - J623-. Refer to appropriate service information. CHECK: Charge Air Pressure Sensor -G31- harness connector terminal 1 to the Engine/Motor Control Module - J623- harness connector T91 / 35 for resistance. CHECK: Charge Air Pressure Sensor -G31- harness connector terminal 3 to the Engine/Motor Control Module - J623- harness connector T91 / 32 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: GO TO: Step 5 Charge Air Pressure Sensor - G31-, CHECKING => 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 Charge Air Pressure Sensor - G31-, CHECKING => 5 .
5	Final Procedure Perform a road test to verify repair. -- Does the original DTC return?	-- YES: CHECK: Engine/Motor Control Module -J623- harness connector for any damaged, pushed-out pins. REPAIR: As necessary. If all electrical connections are OK: REPLACE: Engine/Motor 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 CODES . 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.