Circuit Description
The fuel manager/filter assembly mounted to the engine consists of the fuel heater, the water-in-fuel sensor, and the fuel filter.
The fuel passes through the fuel heater assembly to the fuel filter. The fuel heater assembly contains ceramic heater and a thermostatic switch that opens or closes to turn the heater OFF or ON. The thermostatic switch completes the ground circuit for the fuel heater when fuel temperature is below 8°C (46°F).
The fuel then passes through the fuel filter and to the fuel injection pump.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematic Icons | ||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |
2 |
Does the test lamp illuminate? | -- | Go to Step 3 | Go to Step 5 |
3 |
Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 15 |
4 |
Did you find an open condition? | -- | Go to Step 21 | Go to Step 12 |
5 |
Is the HTD fuel fuse open? | -- | Go to Step 6 | Go to Step 8 |
6 | Probe the ignition 1 voltage circuit of the fuel heater at the harness side with a test lamp connected to battery voltage. Refer to Troubleshooting with a Test Lamp in Wiring Systems. Does the test lamp illuminate? | -- | Go to Step 14 | Go to Step 7 |
7 |
Does the test lamp illuminate? | -- | Go to Step 16 | Go to Step 22 |
8 |
Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 16 |
9 |
Does the test lamp illuminate? | -- | Go to Step 10 | Go to Step 17 |
10 | Probe the heated fuel relay ground circuit with a test lamp connected to battery voltage. Refer to Troubleshooting with a Test Lamp in Wiring Systems. Does the test lamp illuminate? | -- | Go to Step 11 | Go to Step 18 |
11 |
Does the test lamp illuminate? | -- | Go to Step 20 | Go to Step 13 |
12 |
Does the thermostatic switch turn ON when the temperature is within the specified range? | -8.4 to +15.4°C (16.9-59.8°F) | Go to Step 20 | Go to Step 19 |
13 | Repair the open in the ignition 1 voltage circuit between the fuel filter/heater element housing and the heated fuel relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- |
14 | Repair the short to ground on the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- |
15 | Repair the open in the ground circuit between the fuel filter/heater element housing and chassis ground. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- |
16 | Repair the open or short to ground in the battery positive voltage circuit of the heated fuel relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- |
17 | Repair the open or short to ground in the ignition 1 voltage circuit of the heated fuel relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- |
18 | Repair the open in the ground circuit of the heated fuel relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- |
19 | Test for an intermittent and for a poor connection at the fuel heater. Refer to Testing for Intermittent Conditions and Poor Connections and Circuit Testing in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 22 |
20 | Test for an intermittent and for a poor connection at the heated fuel relay. Refer to Testing for Intermittent Conditions and Poor Connections and Circuit Testing in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 23 |
21 | Replace the fuel filter/heater element housing. Refer to Fuel Filter Assembly Replacement . Did you complete the replacement? | -- | Go to Step 24 | -- |
22 | Replace the fuel heater. Refer to Fuel Filter Assembly Replacement . Did you complete the replacement? | -- | Go to Step 24 | -- |
23 | Replace the heated fuel relay. Did you complete the replacement? | -- | Go to Step 24 | -- |
24 |
Does the fuel heater operate properly? | -- | Go to Step 25 | Go to Step 1 |
25 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
