GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2008 🢒 Vibe - FWD 🢒 Engine 🢒 Engine Controls and Fuel - 1.8L (LV6) 🢒 Ignition Relay 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.

Circuit/System Description

The ignition relay, also called the EFI relay, provides ignition positive voltage to the control module and other engine control components anytime the ignition is ON. One side of the coil of the EFI relay is always grounded. The relay is energized when the ignition switch applies voltage to the other side of the coil. The switch side of the EFI relay receives power from the EFI fuse in the fuse block - underhood. When the coil is energized, a magnetic field closes the switch side of the relay, supplying power to the following engine components:

    • Circuit opening relay, also called the fuel pump relay
    • Heated oxygen sensors (HO2S)
    • Mass airflow (MAF) sensor
    • Evaporative emission (EVAP) control system solenoids
    • Powertrain control module (PCM)

Diagnostic Aids
    • The EFI relay electrical contacts may be pitted or sticking. Replace the EFI relay, if gently tapping or wiggling the relay causes a change in the relay's operation.
    • The performance of the EFI relay may be affected by temperature. Check the EFI relay after sitting outside overnight and after running the engine 30 minutes.
    • If the EFI fuse opens during cranking, check for a shorted fuel pump/circuit. The EFI relay supplies current to the circuit opening relay that supplies power the fuel pump. The circuit opening relay is energized during cranking and when reference pulses are detected by the PCM.

Use the following relay cavity table in order to locate the correct cavities to probe during diagnosis. The table layout corresponds to the cavity layout of the relay block.

EFI Relay

Terminal Identification

Relay Switch Output

Relay Switch B+

Relay Coil Control Ignition

Relay Coil Ground

Front of Vehicle

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Powertrain Control Module Connector End Views
    •  Engine Controls Connector End Views

Electrical Information Reference

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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing
  1. Ignition OFF, remove the EFI relay.
  2. Ignition OFF, test for 5 ohms or less between relay coil ground circuit terminal 2 and ground.
    3. ⇒If greater than the specified range, repair the open/high resistance in the relay coil ground circuit.
  3. Ignition OFF, verify that a test lamp does not illuminate between the relay coil control high circuit terminal 1 and ground.
    4. ⇒If the test lamp illuminates, test the coil control circuit for a short to voltage. If the circuit tests normal, ensure the PCM is not receiving false engine speed reference pulses from the crankshaft position (CKP) sensor. If the CKP circuit tests normal, replace the PCM.
  4. Ignition ON, verify that a test lamp illuminates between the relay coil control high circuit terminal 1 and ground.
    5. ⇒If the test lamp does not illuminate, test the coil control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PCM.
  5. Verify that a test lamp illuminates between the relay switch B+ circuit terminal 5 and ground.
    6. ⇒If the test lamp does not illuminate, test the relay switch ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the EFI fuse is open, test the relay controlled output circuit terminal 3 for a short to ground. If the circuit tests normal, test or replace the relay.
  6. Connect a 20A fused jumper between the relay switch B+ circuit terminal 5 and the relay controlled output circuit terminal 3. Verify the relay controlled component of concern activates.
    7. ⇒If the component does not activate, test the relay controlled output circuit for an open/high resistance. If the circuit tests normal, test the component ground circuit for an open/high resistance. If the circuit tests normal, replace the component as necessary.
  7. If all circuits test normal, test or replace the EFI relay.

Component Testing
  1. Ignition OFF, disconnect the EFI relay.
  2. Test for 85-120 ohms at 20°C (68°F) between terminals 1 and 2.
    3. ⇒If the resistance is not within the specified range, replace the relay.
  3. Test for infinite resistance between the following terminals:
    4. • 5 and 1
    • 5 and 2
    • 5 and 3
    • 1 and 3
         ⇒If not the specified range, replace the relay.
  4. Install a 20A fused jumper wire between relay terminal 1 and 12 volts. Install a jumper wire between relay terminal 2 and ground. Test for less than 2 ohms between terminals 5 and 3.
    5. ⇒If greater than the specified range, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for PCM replacement, setup, and programming