Circuit/System Testing

Refer to Testing Ground and Low Reference Circuits for further information on testing the low reference circuits.

1. Ignition Off and all vehicle systems Off. It may take up to 2 minutes for all vehicle systems to power down, disconnect the harness connector at the appropriate reductant heater.
2. Test for less than 5 Ω between the appropriate ground circuit listed below and ground.
   • Reductant heater 1 (reservoir) ground circuit terminal 1
   • Reductant heater 2 (line) ground circuit terminal A or 1
   • Reductant heater 3 (pump) ground circuit terminal 1
   • If 5 Ω or greater 
   1. Ignition Off, disconnect the harness connector at the K34 Glow Plug Control Module.
   2. Test for less than 2 Ω in the low reference circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K34 Glow Plug Control Module.
   • If less than 5 Ω 
3. Connect a test light between the appropriate control circuit listed below and ground.
   • Reductant heater 1 (reservoir) control circuit terminal 2
   • Reductant heater 2 (line) control circuit terminal B or 2
   • Reductant heater 3 (pump) control circuit terminal 2
4. Ignition On.
5. Verify the test lamp turns On when commanding the GPCM Reductant Heater 1, 2 or 3 On with a scan tool.
   • If the test lamp is always Off 
   1. Ignition Off, disconnect the harness connector at the K34 Glow Plug Control Module.
   2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
   3. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K34 Glow Plug Control Module.
   • If the test lamp is always On 
   1. Ignition Off, disconnect the harness connector at the K34 Glow Plug Control Module, ignition On.
   2. Test for less than 1 V between the control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K34 Glow Plug Control Module.
   • If the test lamp turns On 
6. Test for infinite resistance between each terminal listed below and ground:
   NOTE: Do not use the ground circuits in the 24-way harness connector.
   • Reductant heater 1 (reservoir) control circuit terminal 2
   • Reductant heater 2 (line) control circuit terminal B or 2
   • Reductant heater 3 (pump) control circuit terminal 2
   • If less than infinite resistance 

     Repair the short to ground on the circuit

   • If infinite resistance 
7. Measure the resistance on the component between the control circuit and ground circuit terminals listed below. The reading should be between 3-5 Ω for the reductant reservoir heater 1, 2-5 Ω for the reductant line heater 2 and 2-4 Ω for the reductant pump heater 3.
   • Reductant heater 1 (reservoir) control circuit terminal 2 and ground circuit terminal 1
   • Reductant heater 2 (line) control circuit terminal B or 2 and ground circuit terminal A or 1
   • Reductant heater 3 (pump) control circuit terminal 2 and ground circuit terminal 1
   • If not within the specified range 

     Replace the appropriate reductant heater.

   • If within the specified range 
8. All OK.