Circuit/System Testing
WARNING: This page is about a different variant/trim than selected.
- Ignition OFF and all vehicle systems OFF. It may take up to 2min for all vehicle systems to power down. Disconnect the harness connector at the B74 Manifold Absolute Pressure Sensor.
- Test for less than 2Ω between the low reference circuit terminal 2 and ground.
- If 2Ω or greater
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Test for less than 2Ω in the low reference circuit end to end.
- If 2Ω or greater, repair the open/high resistance in the circuit.
- If less than 2Ω, replace the K20 Engine Control Module.
- If less than 2Ω
- Ignition ON.
- Test for 4.8-5.2V between the 5V reference circuit terminal 1 and ground.
- If less than 4.8V
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Test for infinite resistance between the 5V reference circuit and ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- If infinite resistance
- Test for less than 2Ω in the 5V reference circuit end to end.
- If 2Ω or greater, repair the open/high resistance in the circuit.
- If less than 2Ω, replace the K20 Engine Control Module.
- If greater than 5.2V
NOTE:If the signal circuit is shorted to a voltage the ECM or the MAP sensor may be damaged.
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Ignition ON, test for less than 1V between the 5V reference circuit and ground.
- If 1V or greater, repair the short to voltage on the circuit.
- If less than 1V, replace the K20 Engine Control Module.
- If between 4.8-5.2V
- Verify the scan tool MAP Sensor parameter is less than 0.5V.
- If 0.5V or greater
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Test for less than 1V between the signal circuit terminal 3 and ground.
- If 1V or greater, repair the short to voltage on the circuit.
- If less than 1V, replace the K20 Engine Control Module.
- If less than 0.5V
- 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 voltage parameter is greater than 4.5V.
- If 4.5V or less
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Test for infinite resistance between the signal circuit terminal 3 and ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- If infinite resistance
- Test for less than 2Ω in the signal circuit end to end.
- If 2Ω or greater, repair the open or high resistance in the circuit.
- If less than 2Ω, replace the K20 Engine Control Module.
- If greater than 4.5V
- Test or replace the B74 Manifold Absolute Pressure Sensor.