GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Corvette 🢒 Engine 🢒 Engine Electrical 🢒 Ignition Relay Diagnosis

Circuit Description

The ignition relay is normally an 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 contacts to close. The closed relay contacts allow current to flow from the battery to the following fuses:

    • The ENG IGN 1 fuse
    • The INJR 1 fuse
    • The INJR 2 fuse
    • The THROT CONT fuse
    • The A/C Relay fuse

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: Ground Distribution Schematics , Power Distribution Schematics in Wiring Systems and Engine Controls Schematics

Connector End View Reference: Powertrain Control Module Connector End Views

1

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2
  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.
    4. • The ENG IGN 1 fuse
    • The INJR 1 fuse
    • The INJR 2 fuse
    • The THROT CONT fuse
    • The A/C RELAY fuse

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 ENG IGN 1 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 43

4
  1. Turn OFF the ignition.
  2. Remove the ignition relay from the underhood fuse block with the J 43244 Relay Puller Pliers and Relay Replacement in Wiring Systems.
  3. Probe both test points of the 10-amp PCM fuse in the underhood fuse 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 any of the fuse test points?

Go to Step 7

Go to Step 5

5

Test the ignition relay load circuit bus bar of the underhood fuse block between the ignition relay and the fuses to the circuit components for a short to battery positive voltage. Refer to Circuit Testing in Wiring Systems.

Did you find and correct the condition?

Go to Step 42

Go to Step 6

6
  1. Turn OFF the ignition.
  2. Remove the following fuses from the underhood fuse block:
    3. • The ENG IGN 1 fuse
    • The INJR 1 fuse
    • The INJR 2 fuse
    • The THROT CONT fuse
    • The A/C Relay fuse
  3. Probe all these fuse terminals in the underhood fuse 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 Diagnostic System Check - Engine Electrical in Engine Electrical

Go to Step 39

7
  1. Turn OFF the ignition.
  2. Disconnect the ignition switch electrical connector that contains the ignition 1 voltage circuit to the instrument panel (I/P) fuse block.
  3. Probe the ignition 1 voltage terminal of the ignition switch 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 40

Go to Step 8

8
  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  3. Disconnect the I/P fuse block electrical connector that contains the ignition 1 voltage circuit from the ignition switch.
  4. Connect the negative battery cable to the battery.
  5. Probe the ignition 1 voltage circuit between the ignition switch and the I/P fuse 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?

Go to Step 35

Go to Step 9

9
  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  3. Disconnect the underhood fuse block electrical connector that contains the ignition 1 voltage circuit from the ignition relay.
  4. Connect the negative battery cable to the battery.
  5. Probe the ignition 1 voltage circuit of the ignition relay at the underhood fuse 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 38

Go to Step 10

10

Test the ignition 1 voltage bus bar circuit for the ignition relay in the I/P fuse block for a short to battery positive voltage. Refer to Circuit Testing in Wiring Systems.

Did you find a condition?

Go to Step 41

Go to Step 42

11
  1. Turn OFF the ignition.
  2. Probe both test points of the 60-amp IGN 1 fuse in the I/P fuse 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 19

Go to Step 12

12

Does the test lamp illuminate on one test point of the 60-amp IGN 1 fuse?

Go to Step 13

Go to Step 28

13

Test the battery positive voltage circuit between the I/P fuse block and the ignition switch 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 43

Go to Step 14

14

Test the ignition 1 voltage circuit between the ignition switch and the I/P fuse block 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 43

Go to Step 15

15

Test the ignition 1 voltage circuit between the I/P fuse block and the underhood fuse block 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 43

Go to Step 16

16

Test the ignition 1 voltage bus bar circuit of the I/P fuse block between the ignition switch and the underhood fuse block for a short to ground. Refer to Circuit Testing in Wiring Systems.

Did you find a condition?

Go to Step 41

Go to Step 17

17

Test the ignition 1 voltage bus bar circuit of the underhood fuse block up to the 10-amp PCM fuse for a short to ground. Refer to Circuit Testing in Wiring Systems.

Did you find a condition?

Go to Step 42

Go to Step 18

18

Test the battery positive voltage bus bar circuit of the I/P fuse block from the 60-amp ignition 1 fuse for a short to ground. Refer to Circuit Testing in Wiring Systems.

Did you find a condition?

Go to Step 41

Go to Step 40

19
  1. Turn ON the ignition, with the engine OFF.
  2. Probe both test points of the 10-amp PCM fuse in the underhood fuse block with a test lamp that is connected to a good ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

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

Go to Step 29

Go to Step 20

20

Does the test lamp illuminate on one test point of the 10-amp PCM fuse?

Go to Step 27

Go to Step 21

21
  1. Turn ON the ignition, with the engine OFF.
  2. Probe the ignition 1 voltage circuit that leads from the ignition switch to the I/P fuse block 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 24

Go to Step 22

22

Test the battery positive voltage circuit between the I/P fuse block and the ignition switch for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

Go to Step 43

Go to Step 23

23
  1. Turn OFF the ignition.
  2. Probe the mounting stud for the battery positive cable at the I/P fuse 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?

Go to Step 40

Go to Diagnostic System Check - Engine Electrical in Engine Electrical

24
  1. Turn ON the ignition, with the engine OFF.
  2. Probe the ignition 1 voltage circuit for the ignition relay at the I/P fuse block that leads from the ignition switch 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 25

Go to Step 36

25
  1. Turn ON the ignition, with the engine OFF.
  2. Probe the ignition 1 voltage circuit for the ignition relay at the I/P fuse block that leads to the underhood fuse 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?

Go to Step 26

Go to Step 41

26
  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  3. Disconnect the underhood fuse block electrical connector that contains the ignition 1 voltage circuit for the ignition relay.
  4. Connect the negative battery cable at the battery.
  5. Turn ON the ignition, with the engine OFF.
  6. Probe the ignition 1 voltage circuit at the underhood fuse 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 42

Go to Step 37

27

Test the ignition 1 voltage bus bar circuit of the underhood fuse block between the 10-amp PCM fuse and the ignition relay for a short to ground. Refer to Circuit Testing in Wiring Systems.

Did you find a condition?

Go to Step 42

Go to Step 39

28
  1. Turn OFF the ignition.
  2. Probe the mounting stud for the battery positive cable at the underhood fuse 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?

Go to Step 41

Go to Diagnostic System Check - Engine Electrical in Engine Electrical

29
  1. Turn OFF the ignition.
  2. Remove the ignition relay with the J 43244 from the underhood fuse block.
  3. Probe the battery positive voltage circuit of the ignition relay at the underhood fuse 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?

Go to Step 30

Go to Step 42

30
  1. Turn ON the ignition, with the engine OFF.
  2. Probe the ignition 1 voltage circuit of the ignition relay at the underhood fuse 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?

Go to Step 31

Go to Step 42

31
  1. Turn ON the ignition, with the engine OFF.
  2. Probe the coil ground circuit of the ignition relay at the underhood fuse block with a test lamp that is connected to battery voltage. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

Go to Step 33

Go to Step 32

32
  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  3. Disconnect the underhood fuse block electrical connectors.
  4. Test the coil ground circuit wire of the ignition relay at the underhood fuse block electrical connector for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 43

Go to Step 42

33
  1. Turn OFF the ignition.
  2. Jumper the ignition relay battery positive voltage circuit and the ignition relay load circuit together at the underhood fuse block with a 20-amp fused jumper wire. Refer to Using Fused Jumper Wires in Wiring Systems.
  3. Probe the following fuses with a test lamp that is connected to a good ground:
    4. • The ENG IGN 1 fuse
    • The INJR 1 fuse
    • The INJR 2 fuse
    • The THROT CONT fuse
    • The A/C Relay Fuse

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

Go to Step 34

Go to Step 42

34

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

Did you find a condition?

Go to Step 42

Go to Step 39

35

Repair the short to battery positive voltage in the ignition 1 voltage circuit between the ignition switch and the I/P fuse block. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 43

--

36

Repair the high resistance or an open in the ignition 1 voltage circuit between the I/P fuse block and the ignition switch. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 43

--

37

Repair the high resistance or an open in the ignition 1 voltage circuit between the I/P fuse block and the underhood fuse block. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 43

--

38

Repair the short to battery positive voltage in the ignition 1 voltage circuit between the I/P fuse block and the underhood fuse block electrical connector. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 43

--

39

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

Did you complete the replacement?

Go to Step 43

--

40

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 43

--

41

Replace the I/P fuse block. Refer to Instrument Panel Electrical Center or Junction Block Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 43

--

42

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

Did you complete the replacement?

Go to Step 43

--

43
  1. Replace any open fuses.
  2. Turn the ignition OFF for 30 seconds.
  3. Attempt to start the engine.

Does the engine start and run?

Go to Step 44

Go to Engine Cranks but Does Not Run

44
  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

System OK