DTC P2687-P2689
| DTC P2687-P2689 |
| Diagnostic Instructions |
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Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
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Review
Strategy Based Diagnosis
for an overview of the diagnostic approach.
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Diagnostic Procedure Instructions
provides an overview of each diagnostic category.
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| DTC Descriptors |
DTC P2687 00
Fuel Heater Relay Control Circuit
DTC P2688 00
Fuel Heater Relay Control Circuit Low Voltage
DTC P2689 00
Fuel Heater Relay Control Circuit High Voltage
| Diagnostic Fault Information |
| Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
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Fuel Heater Relay Coil Ignition
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1
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1
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-
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-
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Fuel Heater Relay Switch B+
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1
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1
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-
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-
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Fuel Heater Relay Coil Control
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P2688 00
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P2687 00
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P2689 00
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-
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Fuel Heater Relay Controlled Output
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1
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1
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1
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-
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1. The fuse opens and the fuel heater will not operate
2. Fuel Heater Inoperative 3. Fuel Heater Always On |
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| Circuit/System Description |
Ignition voltage is supplied to the coil side of the fuel heater relay whenever the ignition is ON. The engine control module (ECM) provides a ground to control the fuel heater relay. When the ECM is commanding the fuel heater ON, the voltage of the control circuit should be low, near 0 volts. When the ECM is commanding the fuel heater OFF, the voltage of the control circuit should be high, near battery voltage.
| Conditions for Running the DTC |
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The ignition is ON.
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The ignition voltage is less than 16.5 V.
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The DTC runs continuously when the above conditions are met.
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| Conditions for Setting the DTC |
P2687 00
The ECM detects the fuel heater relay control circuit is open for greater than 1 s.P2688 00
The ECM detects the fuel heater relay control circuit is shorted to ground for greater than 1 s.P2689 00
The ECM detects the fuel heater relay control circuit is shorted to battery for greater than 1 s.| Action Taken When the DTC Sets |
DTCs P2687, P2688, and P2689 are type C DTCs.
| Conditions for Clearing the DTC |
DTCs P2687, P2688, and P2689 are type C DTCs.
| Reference Information |
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Fuel System Description
Electrical Information Reference
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Circuit Testing
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Connector Repairs
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Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs
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DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
| Circuit/System Verification |
Ignition ON, the fuel heater relay with turn ON and the fuel heater will turn ON. The Fuel Temperature Sensor parameter on the scan tool will start to rise.
| Circuit/System Testing |
| 1. |
Ignition OFF, disconnect the KR22 Fuel Heater Relay.
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| 2. |
Ignition ON, verify that a test lamp does not illuminate between the fuel heater relay coil control circuit terminal 2 and ground.
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| 3. |
If the test lamp illuminate, test the control circuit for a short to voltage.
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| 4. |
Verify that a test lamp illuminates between the fuel heater relay coil ignition circuit terminal 1 and ground.
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| 5. |
If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test or replace the KR22 Fuel Heater Relay.
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| 6. |
Verify that a test lamp illuminates between the fuel heater relay switch B+ circuit terminal 5 and ground.
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| 7. |
If the test lamp does not illuminate, test the fuel heater relay switch B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the F59UA fuse is open, test the control circuit terminal 3 for a short to ground.
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| 8. |
Disconnect the harness connector X2 at the K20 Engine Control Module.
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| 9. |
Test for less than 2 Ω between the control circuit terminal 2 and K20 Engine Control Module terminal listed below.
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LCD/LBX/LBS Terminal 89 X2
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LBY Terminal 58 X2
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| 10. |
If greater than the specified range, test the ground circuit for an open/high resistance.
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| 11. |
Connect the harness connector at the K20 Engine Control Module and disconnect the harness connector at the E11 Fuel Heater.
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| 12. |
Connect a 15 A fused jumper wire between the fuel heater relay switch B+ circuit terminal 5 and the control circuit terminal 3. Verify a test lamp illuminates between the ignition circuit terminal 3 at the E11 Fuel Heater and ground.
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| 13. |
If the test lamp does not illuminate, test the ignition circuit for an open/high resistance. If the circuit tests normal, test or replace the E11 Fuel Heater.
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| 14. |
Remove the jumper wire. Verify a test lamp does not illuminates between the ignition circuit terminal 3 at the E11 Fuel Heater and ground.
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| 15. |
If the test lamp illuminate, test the ignition circuit for a short to voltage. If the circuits test normal, replace the K20 Engine Control Module.
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| 16. |
Connect a test lamp between the ignition circuit terminal 3 and B+. Verify the test lamp does not illuminate.
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| 17. |
If the test lamp illuminate, test the ignition circuit for an short to ground. If the circuits test normal, replace the K20 Engine Control Module.
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| 18. |
If all circuits test normal, test or replace the KR22 Fuel Heater Relay.
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| Component Testing |
Relay Test
| 1. |
Ignition OFF, disconnect the KR22 Fuel Heater Relay.
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| 2. |
Test for 70-110 Ω between terminals 1 and 2.
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| 3. |
If the resistance is not within the specified range, replace the KR22 Fuel Heater Relay.
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| 4. |
Test for infinite resistance between the following terminals:
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5 and 2
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5 and 3
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5 and 1
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1 and 3
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| 5. |
If not the specified value, replace the KR22 Fuel Heater Relay.
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| 6. |
Test for less than 2 Ω between terminals 3 and 4.
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| 7. |
If greater than the specified range, replace the KR22 Fuel Heater Relay.
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| 8. |
Install a 20 A fused jumper wire between relay terminal 1 and 12 V. Install a jumper wire between relay terminal 2 and ground. Test for less than 2 Ω between terminals 5 and 3.
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| 9. |
If greater than the specified range, replace the KR22 Fuel Heater Relay.
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| Repair Instructions |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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Relay Replacement (Attached to Wire Harness)
Relay Replacement (Within an Electrical Center)
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Control Module References
for ECM replacement, setup, and programming
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