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Home >> GMC >> 2001 >> C3500 HD 6.5 F, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 6.5L - Troubleshooting >> Fuel Heater Inoperative >> Test Description

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  This step checks for a fuel heater that is stuck ON.
  2. 3:  This steps checks for a thermostatic switch that completes the circuit.
Fuel Heater Inoperative

Step Action Yes No
Schematic Reference:  Engine Controls Schematics 
1 Does the Water-In-Fuel lamp operate properly? Go to Step 2  Go to Water-in-Fuel Lamp Inoperative  or Water-in-Fuel Lamp Always On 
2 
  1. Disconnect the fuel heater connector and remove the fuel heater from the filter housing.
  2. With the fuel heater at room temperature, connect the ignition voltage circuit of the fuel heater to B+ and connect the ground circuit of the fuel heater to ground.
  3. Observe the heater element.
Does heat occur?		 Go to Step 4  Go to Step 3 
3 
  1. Cool the sensor part of the fuel heater with ice.
  2. With the fuel heater below 8°C (46°F), wet the heating element with fuel.
  3. Connect the ignition voltage circuit of the fuel heater to B+ and connect the ground circuit of the fuel heater to ground.
  4. Observe the heating element.
Does heat occur?		 Go to Step 5  Go to Step 4 
4 Replace the fuel heater. Refer to Fuel Heater Element Replacement .
Did you complete the repair?		 Go to Step 5  -
5 Operate the vehicle under which the problem was noted.
Does the system operate properly?		 System OK Go to Step 1 
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