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.

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 - Off
Remove the component:KR27 Starter Relay
Verify a test lamp does not turn On between the test points:B+ circuit terminal 30 @ KR27 Starter Relay & Ground
- If the test lamp does not turn On and the circuit fuse is OK
1. Ignition/Vehicle - Off - Remove - Test Lamp
2. Test for less than 2 ohms between the test points:B+ circuit terminal 30 @ KR27 Starter Relay & B+ @ The other end of the circuit
  - If 2 ohms or greater - Repair the open/high resistance in the circuit.
  - If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
- If the test lamp does not turn On and the circuit fuse is open
1. Ignition/Vehicle - Off
2. Test for infinite resistance between the test points:B+ circuit terminal 30 & Ground
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
3. Disconnect the electrical connector:X1 @ M64 Starter Motor
4. Test for infinite resistance between the test points:Control circuit terminal 87 & Ground
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - If infinite resistance - Test or replace the component:M64 Starter Motor
- Go to next step: If the test lamp turns On
Ignition - On / Vehicle - In Service Mode & Engine - Off
Connect a test lamp between the test points:Ignition circuit terminal 86 @ KR27 Starter Relay & Ground
- If the test lamp does not turn On and the circuit fuse is OK
1. Ignition/Vehicle - Off - Remove - Test Lamp
  Test for less than 2 ohms between the test points:Ignition circuit terminal 86 @ KR27 Starter Relay & The other end of the circuit
  - If 2 ohms or greater - Repair the open/high resistance in the circuit.
  - If less than 2 ohms - Refer to:Power Mode Mismatch
- If the test lamp does not turn On and the circuit fuse is open
1. Ignition/Vehicle - Off - Remove - Test Lamp
2. Test for infinite resistance between the test points:Ignition circuit terminal 86 @ KR27 Starter Relay & @ Ground
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
3. Connect - KR27 Starter Relay
  - If the fuse opens - Test or replace the component:KR27 Starter Relay
  - Go to next step: If the fuse is not open
4. All OK.
- If the test lamp is always On
1. Ignition/Vehicle - Off
2. Connect a test lamp between the test points:Ignition circuit terminal 86 @ KR27 Starter Relay & @ Control circuit terminal 85 @ KR27 Starter Relay
3. If available - Perform the scan tool control function:KR27 Starter Relay - On and Off
  or
  
  If available - Cycle the ignition from OFF to ON. - Park Brake Applied - Clutch pedal fully pressed - Manual Transmissionor - Transmission in Park - Automatic Transmission
  
  - Verify the test lamp turns On and Off.
- If the test lamp is always Off
1. Ignition/Vehicle - Off
2. Disconnect the electrical connector: @ K20 Engine Control Module & T19 Power Supply Transformer - Ignition On
3. Test for less than 1 V between the test points:
  - Control circuit terminal @ K20 Engine Control Module & Ground
  - Control circuit terminal @ T19 Power Supply Transformer & Ground
  - If 1 V or greater - Repair the short to voltage on the circuit.
  - Go to next step: If less than 1 V
4. Test for less than 2 ohms between the test points:
  - Control circuit terminal @ K20 Engine Control Module & Control circuit terminal 85 @ KR27 Starter Relay
  - Control circuit terminal @ T19 Power Supply Transformer & Control circuit terminal 85 @ KR27 Starter Relay
  - 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
2. Disconnect the electrical connector:X1 @ K20 Engine Control Module & T19 Power Supply Transformer - Ignition On
3. Test for infinite resistance between the test points:
  - Control circuit terminal @ K20 Engine Control Module & Ground
  - Control circuit terminal @ T19 Power Supply Transformer & Ground
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
4. Connect - K20 Engine Control Module
5. Test for infinite resistance between the test points:
  - Control circuit terminal @ K20 Engine Control Module & Control circuit terminal 85 @ KR27 Starter Relay
  - Control circuit terminal @ T19 Power Supply Transformer & Control circuit terminal 85 @ KR27 Starter Relay
  - If less than infinite resistance - Replace the component:K20 Engine Control Module
  - If infinite resistance - Replace the component:T19 Power Supply Transformer
- Go to next step: If the test lamp turns On and Off
Ignition - On / Vehicle - In Service Mode
Connect a 30 A fused jumper wire between the test points:B+ terminal 30 & Control circuit terminal 87 @ KR27 Starter Relay - Relay Socket
Verify the component activates:M64 Starter Motor
- If the component does not activate
1. Ignition/Vehicle - Off
2. Disconnect the electrical connector:M64 Starter Motor
3. Test for infinite resistance between the test points:Control circuit terminal 87 & Ground
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
4. Test for less than 2 ohms between the test points:
  - Control circuit terminal 87 @ KR27 Starter Relay & Control circuit terminal 1 X1 @ M64 Starter Motor
  - If 2 ohms or greater - Repair the open/high resistance in the circuit.
  - If less than 2 ohms - Test or replace the component:M64 Starter Motor
- Go to next step: If the component activates
Test or replace the component:KR27 Starter Relay