GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Impala 🢒 Engine 🢒 Engine Controls - 3.8L (L36 and L67) 🢒 Ignition Relay Diagnosis

Circuit Description

The ignition relay is a normally open relay. The relay armature is held in the open position by spring tension. When the ignition switch is turned to the run or start position, current will flow through the relay coil. A wire connected to the other end of the relay coil completes the path to ground. The electromagnetic field created by the relay coil, overcomes the spring tension and moves the armature allowing the relay contact to close. The closed relay contacts allow current to flow from the battery to the following fuses:

    • Eng Devices
    • Oxy Sensors
    • DFI/MDL
    • Trans Sol
    • A/C Relay fuse
    • Fuel Inj

When the ignition switch is turned to the OFF position, the electromagnetic field collapses. This action allows the spring tension to move the armature away from the relay contacts, which interrupts current flow to the fuses.

If the ignition relay fails to close, the engine will crank, but will not run. The class 2 communications will be available with the use of a scan tool.

The ignition relay table assumes that the vehicle battery is fully charged. Refer to Battery Inspection/Test in Engine Electrical.

Step

Action

Yes

No

Schematic Reference: Power Distribution Schematics and Ground Distribution Schematics in Wiring Systems and Engine Controls Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn ON the ignition, with the engine OFF.
  2. Remove the underhood bottom junction block cover.
  3. Probe the following fuses with the test lamp that is connected to a good ground:
    4. • Eng Devices
    • Oxy sensors
    • DFI/MDL
    • Trans SOL
    • A/C relay fuse
    • Fuel INJ

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

Go to Step 3

Go to Step 11

3

  1. Turn OFF the ignition.
  2. Probe both test points of the FUEL INJ fuse with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate on either test point of the fuse?

Go to Step 4

Go to Step 33

4

  1. Turn OFF the ignition.
  2. Remove the ignition relay from the underhood bottom junction block with the J 43244 Relay Puller Pliers.
  3. Probe both test points of the 10-amp ABS/PCM fuse with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

Go to Step 7

Go to Step 5

5

Test the ignition relay load circuit between the ignition relay and the fuses to the circuit components for a short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 33

Go to Step 6

6
  1. Turn OFF the ignition.
  2. Remove the following fuses from the underhood bottom junction block:
    3. • Eng Devices
    • Oxy Sen
    • DFI/MDL
    • Trans Sol
    • A/C relay fuse
    • Fuel Inj
  3. Probe all these fuse terminals in the underhood bottom junction block with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate at any of the fuse terminals?

Go to Symptoms - Engine Electrical in Engine Electrical

Go to Step 30

7
  1. Turn OFF the ignition.
  2. Disconnect the left instrument panel (I/P) junction block electrical connector that contains the ignition 1 voltage circuit between the left I/P junction block and the ignition relay.
  3. Test the ignition 1 voltage circuit between the left I/P junction block electrical connector and the ignition relay for a short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 33

Go to Step 8

8

Test the ignition 1 voltage buss bar in the left I/P junction block for a short to battery positive voltage. Refer to Circuit Testing in Wiring Systems.

Did you find a condition?

Go to Step 32

Go to Step 9

9
  1. Turn OFF the ignition.
  2. Disconnect the left I/P junction block electrical connector that contains the ignition 1 voltage circuit between the ignition switch and the left I/P junction block.
  3. Test the ignition 1 voltage circuit between the ignition switch and the left I/P junction block electrical connector for a short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 33

Go to Step 10

10
  1. Turn OFF the ignition.
  2. Probe the ignition 1 voltage circuit at the ignition switch electrical connector with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

Go to Step 31

Go to Step 30

11
  1. Turn OFF the ignition.
  2. Probe both test points of the underhood #2, 60-amp MAXI fuse with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate on both test points of the fuse?

Go to Step 14

Go to Step 12

12

Test the battery positive voltage circuit between the ignition relay and the underhood #2, 60-amp MAXI fuse for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 33

Go to Step 13

13

Test the relay load circuit between the ignition relay and the fuses to the circuit components for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 33

Go to Step 30

14
  1. Turn ON the ignition, with the engine OFF.
  2. Probe both test point of the 10-amp, ABS/PCM fuse in the left I/P junction block with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate on both test points of the fuse?

Go to Step 20

Go to Step 15

15

Does the test lamp illuminate on one test point of the ABS/PCM fuse?

Go to Step 16

Go to Step 17

16
  1. Turn OFF the ignition.
  2. Disconnect the left I/P junction block electrical connector that contains the ignition 1 voltage circuit between the left I/P junction block and the ignition relay.
  3. Test the ignition 1 voltage circuit between the ignition relay and the left I/P junction block electrical connector for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 33

Go to Step 18

17
  1. Turn OFF the ignition.
  2. Disconnect the left I/P junction block electrical connector that contains the ignition 1 voltage circuit from the ignition switch.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 1 voltage circuit at the left I/P junction block electrical connector with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

Go to Step 32

Go to Step 19

18

Test the ignition 1 voltage buss bar in the left I/P junction block for a short to ground. Refer to Circuit Testing in Wiring Systems.

Did you find a condition?

Go to Step 32

Go to Step 30

19
  1. Turn OFF the ignition.
  2. Test the ignition 1 voltage circuit between the ignition switch and the left I/P junction block electrical connector for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 33

Go to Step 31

20
  1. Turn OFF the ignition.
  2. Remove the ignition relay with the J 43244 .
  3. Probe the battery positive voltage circuit of the ignition relay at the underhood bottom junction block with a test lamp that is connected to good ground. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

Go to Step 21

Go to Step 26

21
  1. Turn ON the ignition, with the engine OFF.
  2. Probe the ignition 1 voltage circuit of the ignition relay at the underhood bottom junction block with at test lamp that is connected to a good ground. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

Go to Step 22

Go to Step 25

22
  1. Turn ON the ignition, with the engine OFF.
  2. Probe the coil ground circuit of the ignition relay at the underhood bottom junction block with a test lamp that is connected to a battery voltage. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

Go to Step 23

Go to Step 28

23
  1. Turn OFF the ignition.
  2. Connect a 20-amp fused jumper wire between the battery positive voltage circuit and the load circuit of the ignition relay at the underhood bottom junction block. Refer to Using Fused Jumper Wires in Wiring Systems.
  3. Probe the following fuses with at test lamp that is connected to a good ground:
    4. • Eng Devices
    • Oxy Sensor
    • DFI/MDL
    • Trans Sol
    • A/C relay fuse
    • Fuel INJ

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

Go to Step 24

Go to Step 29

24

Test for an intermittent and for a poor connection at the underhood bottom junction block, ignition relay connector location. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 33

Go to Step 30

25

Test the ignition 1 voltage buss bar circuit in the left I/P junction block between the 10-amp ABS/PCM fuse and the ignition relay for an open.

Did you find a condition?

Go to Step 32

Go to Step 27

26

Repair the high resistance or the open in the battery positive voltage circuit to the ignition relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 33

--

27

Repair the high resistance or the open in the ignition 1 voltage circuit of the ignition relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 33

--

28

Repair the high resistance or the open in the ground circuit of the ignition relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 33

--

29

Repair the high resistance or the open in the load circuit of the ignition relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 33

--

30

Replace the ignition relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 33

--

31

Replace the ignition switch. Refer to Ignition and Start Switch Replacement in Instrument Panel, Gages, and Console.

Did you complete the replacement?

Go to Step 33

--

32

Replace the left instrument panel junction block. Refer to Underhood Electrical Center or Junction Block Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 33

--

33
  1. Replace any open fuses.
  2. Turn OFF the ignition for 30 seconds.

Did you complete the replacement?

Go to Step 34

Go to Engine Cranks but Does Not Run

34
  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

System OK