GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 XLR 🢒 Engine 🢒 Engine Controls - 4.6L (LH2) 🢒 Ignition 1 Relay Diagnosis

Circuit Description

The ignition 1 relay is a normally open relay. The relay armature is held in the open position by spring tension. Battery positive voltage is supplied directly to the ignition 1 relay coil and the armature contact at all times. The engine control module (ECM) supplies the ground path to the relay coil control circuit, via an internal integrated circuit, called an output driver module. When the ECM commands the relay ON, the relay coil creates an electromagnetic field. This electromagnetic field overcomes the spring tension and pulls the armature contact into stationary contact of the relay load circuit. The closing of the relay contacts allows current to flow from the battery to the following fuses and relay:

    • OXY SENSOR FUSE
    • FUEL PUMP FUSE
    • EMISSION FUSE
    • ODD INJECTORS FUSE
    • EVEN INJECTORS FUSE
    • ETC FUSE
    • A/C RELAY

When the ignition switch is turned to the OFF position, power is interrupted to the output driver module in the ECM, and the ignition 1 relay electromagnetic field collapses. This action allows the spring tension pulling on the armature to separate from the relay load circuit contact, which interrupts current flow to the fuses and relay.

If the ignition 1 relay fails to close, the engine will crank, but will not run. The GMLAN and class II data communications will be available, with the use of a CANdi module and scan tool.

Diagnostic Aids
    • The ignition 1 relay will remain powered up for 15 seconds after the ignition switch is turned OFF.
    • The ignition 1 relay system diagnosis table assumes that the vehicle battery is fully charged. Refer to Battery Inspection/Test in Engine Electrical.
    • The underhood fuse block terminal locations correspond to the following ignition 1 relay circuits:
       - F13 -- Ignition 1 voltage circuit
       - F14 -- Ignition 1 relay coil control circuit
       - H13 -- Battery positive voltage to the ignition 1 relay coil
       - H14 -- Battery positive voltage to the ignition 1 relay armature

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check--Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Are DTCs P0686, P0687, P0689 or P0690 set?

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

Go to Step 3

3
  1. Turn ON the ignition, with the engine OFF.
  2. Remove the underhood fuse block cover.
  3. Probe the following fuses with a test lamp that is connected to a good ground. Refer to Troubleshooting with a Test Lamp in Wiring Systems.
    4. • OXY SENSOR FUSE
    • FUEL PUMP FUSE
    • EMISSION FUSE
    • ODD INJECTOR FUSE
    • EVEN INJECTOR FUSE
    • ETC FUSE

Does the test lamp illuminate on at least one test point of each fuse?

Go to Step 6

Go to Step 4

4
  1. Turn OFF the ignition.
  2. Remove the ignition 1 relay from the underhood junction block with the J 43244 Relay Puller Pliers. Refer to Relay Replacement in Wiring Systems.
  3. Connect a 20-amp fused jumper wire from the battery positive voltage terminal for the ignition 1 relay armature at the underhood fuse block to the relay load circuit terminal at the underhood fuse block. Refer to Using Fused Jumper Wires in Wiring Systems.
  4. Probe the following fuses with a test lamp that is connected to a good ground:
    5. • OXY SENSOR FUSE
    • FUEL PUMP FUSE
    • EMISSION FUSE
    • ODD INJECTOR FUSE
    • EVEN INJECTOR FUSE
    • ETC FUSE

Does the test lamp illuminate on at least one test point of each fuse?

Go to Intermittent Conditions

Go to Step 5

5

Replace the underhood fuse block. Refer to Underhood Electrical Center or Junction Block Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 6

--

6
  1. Replace any open fuses.
  2. Turn OFF the ignition for 30 seconds.
  3. Attempt to start the engine.

Does the engine start and run?

Go to Step 7

Go to Intermittent Conditions

7
  1. Clear the DTCs with a scan tool.
  2. Operate the vehicle for 5 minutes.

Does a DTC set during this ignition cycle?

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

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