DTC P2687-P2689
Diagnostic Instructions
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
|
Fuel Heater Relay Coil Ignition
|
1
|
1
|
-
|
-
|
Fuel Heater Relay Switch B+
|
1
|
1
|
-
|
-
|
Fuel Heater Relay Coil Control
|
P2688 00
|
P2687 00
|
P2689 00
|
-
|
Fuel Heater Relay Output Control
|
1
|
2
|
2
|
-
|
1. The fuse opens and the fuel heater will not operate
2. Fuel Heater Inoperative
3. Fuel Heater Always On
|
|
| |
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
| • |
The ignition voltage is less
than 16.5 V. |
| • |
The DTC runs continuously once
the above conditions are met. |
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
Electrical Information Reference
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. |
| 2. |
Ignition ON, verify that a
test lamp does not illuminate between the fuel heater relay coil
control circuit terminal 2 and ground. |
| ⇒ |
If the test lamp illuminate, test the control
circuit for a short to voltage. |
| 3. |
Verify that a test lamp
illuminates between the fuel heater relay coil ignition circuit
terminal 1 and ground. |
| ⇒ |
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. |
| 4. |
Verify that a test lamp
illuminates between the fuel heater relay switch B+ circuit
terminal 5 and ground. |
| ⇒ |
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. |
| 5. |
Disconnect the harness
connector X2 at the K20 Engine Control Module. |
| 6. |
Test for less than 2 Ω
between the control circuit terminal 2 and K20 Engine Control
Module terminal 89 X2. |
| ⇒ |
If greater than the specified range, test the
ground circuit for an open/high resistance. |
| 7. |
Connect the harness connector
at the K20 Engine Control Module and disconnect the harness
connector at the E11 Fuel Heater. |
| 8. |
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
earth. |
| ⇒ |
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. |
| 9. |
Remove the jumper wire. Verify
a test lamp does not illuminates between the ignition circuit
terminal 3 at the E11 Fuel Heater and ground. |
| ⇒ |
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. |
| 10. |
Connect a test lamp between
the ignition circuit terminal 3 and B+. Verify the test lamp does
not illuminate. |
| ⇒ |
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. |
| 11. |
If all circuits test normal,
test or replace the KR22 Fuel Heater Relay. |
Component Testing
Relay Test
| 1. |
Ignition OFF, disconnect the
KR22 Fuel Heater Relay. |
| 2. |
Test for 70-110 Ω
between terminals 1 and 2. |
| ⇒ |
If the resistance is not within the specified
range, replace the KR22 Fuel Heater Relay. |
| 3. |
Test for infinite resistance
between the following terminals: |
| ⇒ |
If not the specified value, replace the KR22 Fuel
Heater Relay. |
| 4. |
Test for less than 2 Ω
between terminals 3 and 4. |
| ⇒ |
If greater than the specified range, replace the
KR22 Fuel Heater Relay. |
| 5. |
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. |
| ⇒ |
If greater than the specified range, replace the
KR22 Fuel Heater Relay. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
Control Module References for ECM replacement, setup, and
programming
|
