Circuit/System Testing

WARNING: This page is about a different car, the 2019 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.

Vehicle Off.
Remove the component:KR75 Engine Controls Ignition Relay
Verify a test lamp turns On between the test points:
- B+ circuit terminal 87 & Ground
- B+ circuit terminal 85 & Ground
- If the test lamp does not turn On
  Replace the component:X50A Fuse Block - Underhood
- Go to next step: If the test lamp turns On
Ignition - On / Vehicle - In Service Mode
Connect a test lamp between the test points:Control circuit terminal 86 & B+ circuit
Perform the scan tool control function:KR75 Engine Controls Ignition Relay - On and Off
Verify the test lamp turns On and Off.
- If the test lamp is always Off
1. Ignition/Vehicle - Off & Remove - Test lamp
2. Disconnect the electrical connector:X1 @ K20 Engine Control Module
3. Ignition - On / Vehicle - In Service Mode
4. Test for less than 1 V between the test points: Control circuit terminal 86 @ Relay Socket & Terminal 9 @ Control module harness
  - If 1 V or greater - Repair the short to voltage on the circuit.
  - Go to next step: If less than 1 V
5. Ignition/Vehicle - Off
6. Test for less than 2 ohms between the test points:Control circuit terminal 86 @ Relay Socket & Terminal 9 @ Control module harness
  - If 2 ohms or greater - Repair the open/high resistance in the circuit.
  - If less than 2 ohms - Replace the component:K20 Engine Control Module
- If the test lamp is always On
1. Ignition/Vehicle - Off & Remove - Test lamp
2. Disconnect the electrical connector:X1 @ K20 Engine Control Module
3. Test for infinite resistance between the test points:Control circuit terminal 86 @ Relay Socket & Ground
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - If infinite resistance - Replace the component:K20 Engine Control Module
- Go to next step: If the test lamp turns On and Off
Verify the fuse is not open:
- F74UA Fuse
- F75UA Fuse
- If the fuse is open
1. Vehicle Off.
2. Disconnect the electrical connector: X1 @ K20 Engine Control Module
3. Test for infinite resistance between the test points:Output terminal @ Fuse & Ground
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - If infinite resistance - Replace the component: K20 Engine Control Module
- Go to next step: If the fuse is not open
Ignition - On / Vehicle - In Service Mode
Verify a test lamp does not turn On between the test points:KR75 Engine Controls Ignition RelayTerminal 30 & Ground
- Go to next step: If the test lamp turns On
Disconnect the electrical connector: X1 @ K20 Engine Control Module
Test for less than 1 V between the test points:
- Control circuit terminal 48 @ Control module harness & Ground
- Control circuit terminal 49 @ Control module harness & Ground
- If 1 V or greater - Repair the short to voltage on the circuit.
- Go to next step: If the test lamp does not turn On
Vehicle Off.
Connect a 30 A fused jumper wire between the test points:Control circuit terminal 30 & B+ circuit terminal 87
Ignition - On / Vehicle - In Service Mode
Verify the scan tool parameter:Engine Controls Ignition Relay Feedback Signal = Within 1 V of the battery voltage
- If not within 1 V of the battery voltage
1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
2. Disconnect the electrical connector: X1 @ K20 Engine Control Module
3. Test for less than 2 ohms between the test points:
  - Control circuit terminal 30 @ Relay Socket & Control circuit terminal 48 @ Control module harness
  - Control circuit terminal 30 @ Relay Socket & Control circuit terminal 49 @ Control module harness
  - If 2 ohms or greater - Repair the open/high resistance in the circuit.
  - If less than 2 ohms - Replace the component: K20 Engine Control Module
- Go to next step: If within 1 V of the battery voltage
Test or replace the component:KR75 Engine Controls Ignition Relay