Fuel Pump Electrical Circuit Diagnosis
Diagnostic Instructions
Diagnostic Fault Information
Circuit
|
Short to Ground
|
Open/High Resistance
|
Short to Voltage
|
Signal Performance
|
Fuel Pump Relay Ignition Voltage
|
*
|
P0627 00**
|
-
|
-
|
Fuel Pump Motor Supply Voltage
|
*
|
**
|
***
|
-
|
Fuel Pump Relay Control
|
P0628 00**
|
P0627 00**
|
P0629 00***
|
-
|
Fuel Pump Relay Ground
|
-
|
**
|
-
|
-
|
Fuel Pump Ground
|
-
|
**
|
-
|
-
|
* The fuel pump fuse opens and the engine cranks but does not
run.
** The engine cranks but does not run.
*** The fuel pump operates continuously and the battery will
discharge.
|
|
|
Circuit/System Description
When you turn ON the ignition switch, the engine control module
(ECM) energizes the fuel pump relay which powers the fuel pump ON.
The fuel pump remains ON as long as the engine is cranking or
running and the ECM receives ignition reference pulses. If there
are no ignition reference pulses, the ECM shuts the fuel pump OFF
within 2 s after the ignition was switched to the ON position or if
the engine stops.
Diagnostic Aids
The following conditions may cause the fuel pump fuse to
open:
• |
There is an intermittent short
to ground in the supply voltage circuit of the fuel pump.
|
• |
The fuel pump has an
intermittent internal condition. |
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Special Tools
EL 43244 Relay Puller Pliers
For equivalent regional tools, refer to
Special Tools .
Circuit/System Verification
1. |
Ignition ON, command the Fuel
Pump Relay ON and OFF with a scan tool. You should hear and feel a
click when you command the fuel pump relay ON and OFF. |
2. |
Operate the vehicle within the
Conditions for Running the DTC to verify the DTC does not reset.
You may also operate the vehicle within the conditions that you
observed from the Freeze Frame/Failure Records data. |
Circuit/System Testing
1. |
Ignition OFF, the fuel pump
should not be running. |
⇒ |
If the fuel pump runs continuously, test the fuel
pump motor supply voltage circuit for a short to voltage. If the
circuit tests normal, replace the fuel pump relay. |
2. |
Ignition OFF, remove the KR23A
Fuel Pump Relay from the X50A Fuse Block - Underbonnet Primary with
the EL 43244 Relay Puller Pliers . |
3. |
Test for less than 5 Ω
between the earth circuit terminal 85 and earth. |
⇒ |
If greater than the specified range, repair the
ground circuit for an open/high resistance. |
4. |
Ignition ON, verify a test
lamp illuminates between the relay switch ignition circuit terminal
30 and ground. |
⇒ |
If the test lamp does not illuminate, repair the
ignition circuit for a short to ground or an open/high resistance.
Replace the fuse if necessary. |
5. |
Connect a 15 A fused jumper
wire between the relay switch ignition circuit terminal 30 and the
relay switch supply circuit terminal 87. The fuel pump should turn
ON. |
⇒ |
If the fuel pump does not turn ON, test for the
following conditions: |
|
• |
An open/high resistance in the
relay switch supply circuit |
|
• |
An open/high resistance in the
G12 Fuel Pump ground circuit |
⇒ |
If the above circuits test normal, replace the G12
Fuel Pump. |
6. |
Ignition OFF, connect a test
lamp between the relay coil control circuit terminal 86 and
ground. |
7. |
Ignition ON, command the Fuel
Pump Relay ON and OFF with a scan tool. The test lamp should turn
ON and OFF with each command. |
⇒ |
If the test lamp is always ON, test the relay coil
control circuit for a short to voltage. If the circuit tests
normal, replace the K20 Engine Control Module. |
⇒ |
If the test lamp is always OFF, test the relay
coil control circuit for a short to ground or an open/high
resistance. If circuit tests normal, replace the K20 Engine Control
Module. |
8. |
If all circuits test normal,
test or replace the KR23A Fuel Pump Relay. |
Component Testing
Relay Test
1. |
Ignition OFF, remove the fuel
pump relay from the electrical centre with the EL 43244
Relay Puller Pliers . |
2. |
Test for 70-110 Ω
between terminals 85 and 86. |
⇒ |
If not within the specified range, replace the
KR23A Fuel Pump Relay. |
3. |
Test for infinite resistance
between the following terminals: |
⇒ |
If not the specified value, replace the KR23A Fuel
Pump Relay. |
4. |
Install a 20 A fused jumper
wire between terminal 85 and B+. Install a jumper wire between
terminal 86 and ground. Test for less than 2 Ω between
terminals 30 and 87. |
⇒ |
If greater than the specified range, replace the
KR23A Fuel Pump Relay. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
Fuel Tank Fuel Pump Module Replacement
|