Circuit/System Testing

• If the test lamp does not turn On 

1. Ignition/Vehicle - Off & Remove - Test lamp
2. Remove the component: KR75 Engine Controls Ignition Relay
3. Test for less than 2 ohms between the test points: Ignition circuit terminal 2 @ KR22 Fuel Heater Relay - Relay Socket & Control circuit terminal 5 @ KR75 Engine Controls Ignition Relay - Relay Socket
   • If 2 ohms or greater - Replace the component: X50A Fuse Block - Underhood
   • If less than 2 ohms - Refer to: DTC P0685-P0687, P0689, P0690, P1682, P16A7, P16AF, or P16B3

• Go to next step: If the test lamp turns On 

• If the test lamp turns On 

1. Ignition/Vehicle - Off & Remove - Test lamp
2. Disconnect the electrical connector: X3 @ K20 Engine Control Module
3. Test for infinite resistance between the test points: Control circuit terminal 1 @ 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 does not turn On 

Verify the scan tool parameter: Fuel Heater Relay Control Circuit High Voltage Test Status = OK

• If not the specified state 

1. Ignition/Vehicle - Off
2. Disconnect the electrical connector: X3 @ 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 @ Relay Socket & 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 specified state 

Verify the scan tool parameter: Fuel Heater Relay Control Circuit High Voltage Test Status = Malfunction

• If not the specified state 

1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
2. Disconnect the electrical connector: X3 @ K20 Engine Control Module
3. Test for less than 2 ohms between the test points: Control circuit terminal 1 @ Relay Socket & Terminal 45 @ 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 the specified state 

• 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 5 @ Relay Socket & Output terminal @ E11A Fuel Heater/Water in Fuel Sensor F25UA Fuse
   • 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 & Remove - Test lamp
2. Test for infinite resistance between the test points: B+ circuit terminal 5 & 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: E11A Fuel Heater/Water in Fuel Sensor
4. Test for infinite resistance between the test points: Control circuit terminal 3 @ Relay Socket & Ground
   • If less than infinite resistance - Repair the short to ground on the circuit.
   • Go to next step: If infinite resistance
5. Replace the component: E11A Fuel Heater/Water in Fuel Sensor F25UA Fuse
6. Install the component: KR22 Fuel Heater Relay
7. Connect a test lamp between the test points: Control circuit terminal 6 & Ground circuit terminal 7
8. Ignition - On/Vehicle - In Service Mode
9. Perform the scan tool control function: Fuel Heater Relay - On and Off

   Verify the test lamp turns On and Off.

   • If the test lamp does not turn On and Off - Test or replace the component: KR22 Fuel Heater Relay
   • If the test lamp turns On and Off - Test or replace the component: E11A Fuel Heater/Water in Fuel Sensor

• Go to next step: If the test lamp turns On 

• If 10 ohms or greater 

1. Disconnect the ground connection: G307
2. Test for less than 2 ohms between the test points: Ground circuit terminal 7 @ Component harness & Terminal G307
   • If 2 ohms or greater - Repair the open/high resistance in the circuit.
   • If less than 2 ohms - Repair the open/high resistance in the ground connection.

• Go to next step: If less than 10 ohms 

Verify the test lamp turns On and Off.

• If the test lamp is always Off 

1. Ignition/Vehicle & All vehicle systems - Off
2. Remove the component: KR22 Fuel Heater Relay
3. Test for less than 2 ohms between the test points: Control circuit terminal 3 @ Relay Socket & Control circuit terminal 6 @ Component harness
   • If 2 ohms or greater - Repair the open/high resistance in the circuit.
   • If less than 2 ohms - Test or replace the component: KR22 Fuel Heater Relay

• If the test lamp is always On 

  Repair the short to voltage on the circuit: Control Circuit

• Go to next step: If the test lamp turns On and Off