Circuit/System Testing

WARNING: This page is about a different car, the 2017 GMC Acadia. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

Ignition/Vehicle & All vehicle systems » Off
Disconnect the electrical connector:B74 Manifold Absolute Pressure Sensor
Test for less than 10 Ω between the test points:Low Reference circuit terminal 2 & Ground
- If 10 Ω or greater
1. Disconnect the electrical connector:K20 Engine Control Module
2. Test for less than 2 Ω between the test points:Low Reference circuit terminal 2 @Component harness & Terminal 48 X2 @Control module harness
  - If 2 Ω or greater » Repair the open/high resistance in the circuit.
  - If less than 2 Ω » Replace the component:K20 Engine Control Module
- If less than 10 Ω
Ignition » On / Vehicle » In Service Mode
Test for 4.8 to 5.2 V between the test points: 5 V Reference circuit terminal 1 & Low Reference circuit terminal 2
- If less than 4.8 V
1. Ignition/Vehicle » Off
2. Disconnect the electrical connector:K20 Engine Control Module
3. Test for infinite resistance between the test points: 5 V Reference circuit terminal 1 @Component harness & Ground
  - If less than infinite resistance » Repair the short to ground on the circuit.
  - If infinite resistance
4. Test for less than 2 Ω between the test points: 5 V Reference circuit terminal 1 @Component harness & Terminal 47 X2 @Control module harness
  - If 2 Ω or greater » Repair the open/high resistance in the circuit.
  - If less than 2 Ω » Replace the component:K20 Engine Control Module
- If greater than 5.2 V
1. Ignition/Vehicle » Off
2. Disconnect the electrical connector:K20 Engine Control Module
3. Ignition » On / Vehicle » In Service Mode
4. Test for less than 1 V between the test points: 5 V Reference circuit terminal 1 @Component harness & Ground
  - If 1 V or greater » Repair the short to voltage on the circuit.
  - If less than 1 V » Replace the component:K20 Engine Control Module
- If between 4.8 and 5.2 V
Verify the scan tool parameter:MAP Sensor =Greater than 4.7 V
- If 4.7 V or less
1. Ignition/Vehicle » Off
2. Disconnect the electrical connector:K20 Engine Control Module
3. Test for infinite resistance between the test points:Signal circuit terminal 3 @Component harness & Ground
  - If less than infinite resistance » Repair the short to ground on the circuit.
  - If infinite resistance » Replace the component:K20 Engine Control Module
- If greater than 4.7 V
Connect a 3 A fused jumper wire between the test points:Signal circuit terminal 3 & Low Reference circuit terminal 2
Verify the scan tool parameter:MAP Sensor =Less than 0.2 V
- If 0.2 V or greater
1. Ignition/Vehicle » Off & Remove » Jumper wire(s)
2. Disconnect the electrical connector:K20 Engine Control Module
3. Ignition » On / Vehicle » In Service Mode
4. Test for less than 1 V between the test points:Signal circuit terminal 3 @Component harness & Ground
  - If 1 V or greater » Repair the short to voltage on the circuit.
  - If less than 1 V
5. Ignition/Vehicle » Off
6. Test for less than 2 Ω between the test points:Signal circuit terminal 3 @Component harness & Terminal 67 X3 @Control module harness
  - If 2 Ω or greater » Repair the open/high resistance in the circuit.
  - If less than 2 Ω » Replace the component:K20 Engine Control Module
- If less than 0.2 V
Replace the component:B74 Manifold Absolute Pressure Sensor