MAF Sensor Checking Before May 2010 <
Use only gold-plated terminals when servicing terminals in harness connector of Mass Air Flow (MAF) Sensor -G70-.
Special tools and workshop equipment required
- Multimeter.
- Wiring diagram.
Test requirements
- The Mass Air Flow (MAF) Sensor -G70- fuse is OK.
- Battery voltage at least 12.5 volts.
- All electrical consumers such as, lights and rear window defroster, switched off.
- Vehicles with automatic transmission, shift selector lever into position "P" or "N".
- A/C switched off.
- Ground connections between engine/transmission/chassis OK.
- Coolant Temperature at least 80° C.
- Ignition switched OFF.
Test procedure
-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK
Start diagnosis
-- Connect the scan tool.
-- Start engine and let it run at idle.
-- Using the scan tool, Check the air flow quantity of the Mass Air Flow (MAF) Sensor -G70- at idle:
| Diagnostic text | Specified value | |||
|---|---|---|---|---|
| Air flow quantity at Mass Air Flow (MAF) sensor | ||||
|
2.50 to 5.50 g/sec. | |||
-- Turn the ignition switch OFF.
If specified value is obtained: condition not present.
-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
If the specified value was Not obtained:
Checking voltage supply
-- Disconnect the Mass Air Flow (MAF) Sensor -G70- electrical harness connector -1-.
-- Start the engine and let it run at idle.
-- Using a multimeter, check the Mass Air Flow (MAF) Sensor -G70- electrical harness connector terminal 3 to engine Ground.
Specified value: Battery voltage.
-- Switch the ignition OFF.
If the specified value was Not obtained:
-- Remove the fuse 15 in Fuse Panel C. Check the Mass Air Flow (MAF) Sensor -G70- electrical harness connector terminal 3 to Fuse 15 in Fuse Panel C for an open circuit or high resistance.
Specified value: 1.5 Ω max.
-- If necessary, repair the faulty wiring connection.
If the specified value was obtained:
Checking electrical circuit
-- Using a multimeter connected to ground, check terminals 1, 2 and 5 of the MAF connector for voltage.
Specified values:
| Terminal | Specified voltage |
|---|---|
| 1 | 3.10 V (+/-.6 V) |
| 2 | 0 V |
| 5 | 4.88 V (+/-.5 V) |
If the specified value was Not obtained:
-- Remove the Engine Control Module (ECM) -J623-. Refer to the Repair information.
-- Using a multimeter, check the Mass Air Flow (MAF) Sensor -G70- electrical harness connector terminals to the Engine Control Module (ECM) -J623- electrical harness connector T94 terminals for an open circuit.
| Mass Air Flow (MAF) Sensor -G70- electrical harness connector terminals: | Engine Control Module (ECM) -J623- electrical connector T94 terminals: |
|---|---|
| 1 | 23 |
| 2 | 65 |
| 4 | 12 |
| 5 | 60 |
Specified value: 1.5 Ω max.
If the specified value was Not obtained:
-- Check the wiring for an open, high resistance or short to Battery positive or ground.
-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
-- If necessary, repair the faulty wiring connection.
If no malfunction is detected in the wiring and the voltage supply was OK:
-- Replace Mass Air Flow (MAF) Sensor -G70- Refer to the Repair information.
If no malfunction is detected in the wiring and the voltage supply was Not OK:
-- Replace the Engine Control Module (ECM) -J623-. Refer to the Repair information.
Final procedures
After the repair work, the following work steps must be performed in the following sequence:
- Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
- If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
- If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .