To the top of the document
Cruze
   
GMDE Start Page Load static TOC Load dynamic TOC Help?

Fuel Pump Electrical Circuit Diagnosis

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    • Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Fuel Pump Relay Ignition 1 Voltage

*

**

-

-

Fuel Pump Motor Supply Voltage

*

**

***

-

Fuel Pump Relay Control

**

**

***

-

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) energises 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:

    • The fuse is faulty.
    • 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 : LLW

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

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.

Circuit/System Testing
  1. Ignition OFF, the fuel pump should not be running.
    2. ⇒If the fuel pump runs continuously, test for a short to voltage. If the circuit tests normal, replace the fuel pump relay.
  2. Ignition OFF, remove the fuel pump relay from the electrical centre.
  3. Test for less than 5 Ω between the ground circuit terminal 85 and ground.
    4. ⇒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 B+ circuit terminal 30 and ground.
    5. ⇒If the test lamp does not illuminate, repair the B+ 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 B+ circuit terminal 30 and the relay switch supply circuit terminal 87. The fuel pump should turn ON.
    6. ⇒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 ground circuit
    ⇒If the above circuits test normal, replace the A6 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.
    8. ⇒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 the circuit tests normal, replace the K20 Engine Control Module.
  8. If all circuits test normal, test or replace the fuel pump relay.

Component Testing

Dynamic Test

  1. Ignition OFF, remove the fuel pump relay from the electrical centre.
  2. Test for 70-110 Ω between terminals 85 and 86.
    3. ⇒If not within the specified range, replace the relay.
  3. Test for infinite resistance between the following terminals:
    4. • 30 and 86
    • 30 and 87
    • 30 and 85
    • 85 and 87
    ⇒If not the specified value, replace the 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.
    5. ⇒If greater than the specified range, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Fuel Sender Assembly Replacement

   


© Copyright Chevrolet. All rights reserved