Circuit/System Testing
WARNING: This page is about a different variant/trim than selected.
- Verify the integrity of the entire air induction system and verify that none of the following conditions exist:
- Any damaged components
- Improper operation of turbocharger wastegate actuator or bypass valve; if equipped
- Loose or improper installation of the turbocharger and the charge air cooler, including the flexible ductwork; if equipped
- An air flow restriction
- Any vacuum leak
- Improperly routed vacuum hoses
- A restriction in the MAP Sensor port, or the BARO port; where equipped
- Proper operation of the positive crankcase ventilation system
- Missing, restricted or leaking exhaust components. Refer to Symptoms - Engine Exhaust .
- Engine mechanical condition; for example: low compression or incorrect timing chain installation. Refer to Symptoms - Engine Mechanical .
- If a condition is found
If a condition is found, repair or replace the component as appropriate.
- Go to next step: If no condition is found
- Ignition OFF and all vehicle systems OFF. It may take up to 2 min for all vehicle systems to power down. Disconnect the harness connector at the B74 Manifold Absolute Pressure Sensor.
- Test for less than 2 Ω between the low reference circuit terminal 2 and ground.
- If 2 Ω or greater
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Test for less than 2 Ω in the low reference circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K20 Engine Control Module.
- Go to next step: If less than 2 Ω
- Ignition ON.
- test for 4.8 - 5.2 V between the 5 V reference circuit terminal 1 and ground.
- If less than 4.8 V
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Test for infinite resistance between the 5 V reference circuit and ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in the 5 V reference circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K20 Engine Control Module.
- If greater than 5.2 V
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 1 V between the 5 V reference circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the K20 Engine Control Module.
- Go to next step: If between 4.8 - 5.2 V
- Verify the scan tool MAP Sensor parameter is less than 0.5 V.
- If 0.5 V or greater
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON
- Test for less than 1 V between the signal circuit terminal 3 and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the K20 Engine Control Module.
- Go to next step: If less than 0.5 V
- Install a 3 A fused jumper wire between the signal circuit terminal 3 and the 5 V reference circuit terminal 1.
- Ignition ON, verify the scan tool MAP voltage parameter is greater than 4.5 V.
- If 4.5 V 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.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in the signal circuit end to end.
- If 2 Ω or greater, repair the open or high resistance in the circuit.
- If less than 2 Ω, replace the K20 Engine Control Module.
- Go to next step: If greater than 4.5 V
- Test or replace the B74 Manifold Absolute Pressure Sensor.