Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.

Ignition/Vehicle - Off
Disconnect the appropriate electrical connector :
- Q18A Fuel Pressure Regulator 1
- Q18B Fuel Pressure Regulator 2
Connect a test lamp between the test points : Control circuit terminal 2 & B+
Ignition - On / Vehicle - In Service Mode
Perform the appropriate scan tool control function : Fuel Pressure Regulator 1, 2 - On and Off
Verify the test lamp turns On and changes brightness.
- If the test lamp is always Off
1. Ignition/Vehicle - Off & Remove - Test lamp
2. Disconnect the appropriate electrical connector :
  - {Q18A Fuel Pressure Regulator 1} X1 @ K20 Engine Control Module
  - {Q18B Fuel Pressure Regulator 2} X2 @ 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 2 @ Component harness & Ground
  - 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 2 @ Component harness & The other end of the circuit @ 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 turns On but does not change brightness
1. Ignition/Vehicle - Off & Remove - Test lamp
2. Disconnect the appropriate electrical connector :
  - {Q18A Fuel Pressure Regulator 1} X1 @ K20 Engine Control Module
  - {Q18B Fuel Pressure Regulator 2} X2 @ K20 Engine Control Module
3. Test for infinite resistance between the test points : Control circuit terminal 2 @ 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
- Go to next step : If the test lamp turns On and changes brightness
Connect a test lamp between the test points : Control circuit terminal 1 & Control circuit terminal 2
Perform the appropriate scan tool control function : Fuel Pressure Regulator 1, 2 - On and Off
Verify the test lamp turns On and changes brightness.
- If the test lamp is always Off
1. Ignition/Vehicle - Off & Remove - Test lamp
2. Disconnect the appropriate electrical connector :
  - {Q18A Fuel Pressure Regulator 1} X1 @ K20 Engine Control Module
  - {Q18B Fuel Pressure Regulator 2} X2 @ K20 Engine Control Module
3. Test for infinite resistance between the test points : Control circuit terminal 1 @ Component harness & 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 1 @ Component harness & The other end of the circuit @ 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 turns On but does not change brightness
1. Ignition/Vehicle - Off & Remove - Test lamp
2. Disconnect the appropriate electrical connector :
  - {Q18A Fuel Pressure Regulator 1} X1 @ K20 Engine Control Module
  - {Q18B Fuel Pressure Regulator 2} X2 @ 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 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
- Go to next step : If the test lamp turns On and changes brightness
Test or replace the component : Q18 Fuel Pressure Regulator