Circuit/System Testing
NOTE:
All electrical components and accessories must be turned OFF and allowed to power down.
- Verify the integrity of the air induction system by inspecting for the following conditions:
- Any damaged components
- Loose or improper installation
- Improperly routed vacuum hoses
- Any vacuum leaks
- Any type of restriction
- MAP sensor seal that is missing or damaged
- Ignition OFF, and all vehicle systems OFF, disconnect the harness connector at the B74 MAP sensor. It may take up to 2 minutes for all vehicle systems to power down.
- Test for less than 5 Ω between the low reference circuit terminal 2 and ground.
- If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
- Ignition ON, test for 4.8-5.2 V between the 5V reference circuit terminal 1 and ground.
- If less than the specified range, test the 5V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
- If greater than the specified range, test the 5V reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Verify the scan tool MAP Sensor parameter is less than 104 kPa (15.1 psi).
- If greater than the specified range, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the ECM.
- Install a 3A fused jumper wire between the signal circuit terminal 3 and the 5V reference circuit terminal 1. Verify the scan tool MAP Sensor parameter is greater than 103 kPa (14.9 psi).
- If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
- If all circuits test normal, test or replace the MAP sensor.