LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1469 (Engine Control System - 4.8L, 5.3L, & 6.0L - Troubleshooting & Diagnosis) >> Diagnostic Information & Procedures >> Ignition Relay Diagnosis >> Circuit Description

Circuit Description

WARNING: This page is about a different car, the 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 Chevrolet TrailBlazer, and 2004 Buick Rainier. However, it is still accessible from the selected car via links, so may be relevant.

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 pulls the armature contact into the stationary contact of the relay load circuit. The closed relay contacts allows current to flow from the battery to the following fuses:

When the ignition switch is turned to the OFF position, the electromagnetic field collapses. This action allows the spring tension to move the armature contact away from the relay load circuit 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 (Non-HP2) in Engine Electrical.

Ignition Relay Diagnosis

Step Action Yes No
Schematic Reference:  Power Distribution Schematics  and  Ground Distribution Schematics  in Wiring Systems and  Engine Controls Schematics 
Connector End View Reference:  Engine Controls Component Views  or  Powertrain Control Module (PCM) 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:
Does the test lamp illuminate on at least one test point of each fuse?		 Go to Step 3  Go to Step 10 
3
  1. Turn OFF the ignition.
  2. Probe both test points of the ETC 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 35 
4
  1. Turn OFF the ignition.
  2. Remove the ignition relay from the underhood fuse block with the J 43244  Relay Puller Pliers. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems.
    3. NOTE: Refer to Test Probe Notice in Cautions and Notices.
  3. 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 7  Go to Step 5 
5
  1. Turn OFF the ignition.
  2. Remove the following fuses from the underhood fuse block:
    • ETC
    • INJ A
    • INJ B
  3. Probe the above 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 Step 6  Go to Step 32 
6 Test the relay load bus bar circuit of the underhood fuse block between the ignition relay and the following fuses for a short to battery positive voltage:
Did you find a condition?		 Go to Step 34  Go to Diagnostic System Check - Engine Electrical in Engine Electrical
7
  1. Turn OFF the ignition.
  2. Disconnect the ignition switch electrical connector.
  3. Connect a 20-amp fused jumper wire from the battery positive voltage terminal on the vehicle harness side of the ignition switch electrical connector to the corresponding battery positive voltage terminal on the ignition switch. Refer to Using Fused Jumper Wires in Wiring Systems.
  4. Probe the ignition 1 voltage terminal on 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 33  Go to Step 8 
8
  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnect/Connect Procedure in Engine Electrical.
  3. Disconnect the underhood 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 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 31  Go to Step 9 
9 Test the ignition 1 voltage bus bar circuit of the ignition relay in the underhood fuse block for a short to battery positive voltage. Refer to Circuit Testing in Wiring Systems.
Did you find a condition?		 Go to Step 34  Go to Step 32 
10
  1. Turn OFF the ignition.
  2. Inspect the 40-amp IGN B fuse in the underhood fuse block. Refer to Circuit Protection - Fuses in Wiring Systems.
Is the fuse open?		 Go to Step 11  Go to Step 18 
11
  1. Remove the 40-amp IGN B fuse from the underhood fuse block.
    2. NOTE: Refer to Test Probe Notice in Cautions and Notices.
  2. Probe both 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 on at least one fuse terminal?		 Go to Step 12  Go to Step 17 
12
  1. Turn OFF the ignition.
  2. Disconnect the ignition switch electrical connector.
  3. Probe the battery positive voltage terminal on the vehicle harness side of the ignition switch electrical connector with a test lamp that is connected to battery positive voltage. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.
Does the test lamp illuminate?		 Go to Step 28  Go to Step 13 
13
  1. Turn OFF the ignition.
  2. Probe the ignition 1 voltage terminal on the ignition switch with a test lamp that is connected to battery positive 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 14 
14
  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnect/Connect Procedure in Engine Electrical.
  3. Disconnect the underhood 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 of the ignition relay at the underhood fuse block electrical connector with a test lamp that is connected to battery positive voltage. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.
Does the test lamp illuminate?		 Go to Step 29  Go to Step 15 
15 Test the ignition 1 voltage bus bar circuit for the ignition relay in the underhood fuse block for a short to ground. Refer to Circuit Testing in Wiring Systems.
Did you find a condition?		 Go to Step 34  Go to Step 16 
16 Test the battery positive voltage bus bar circuit of the underhood fuse block that leads from the 40-amp IGN B fuse to the ignition switch for a short to ground. Refer to Circuit Testing in Wiring Systems.
Did you find a condition?		 Go to Step 34  Go to Step 32 
17
  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 34  Go to Diagnostic System Check - Engine Electrical in Engine Electrical
18
  1. Turn OFF the ignition.
  2. Remove the ignition relay from the underhood fuse block with the J 43244  . Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems.
    3. NOTE: Refer to Test Probe Notice in Cautions and Notices.
  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 19  Go to Step 34 
19
  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 24  Go to Step 20 
20
  1. Turn OFF the ignition.
  2. Disconnect the ignition switch electrical connector.
  3. Probe the battery positive voltage circuit from the 40-amp IGN B fuse on the vehicle wire harness side of 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 22  Go to Step 21 
21
  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnect/Connect Procedure in Engine Electrical.
  3. Disconnect the underhood fuse block electrical connector that contains the battery positive voltage circuit from the 40-amp IGN B fuse.
  4. Test the battery positive voltage circuit between the underhood 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 the condition?		 Go to Step 35  Go to Step 34 
22
  1. Turn OFF the ignition.
  2. Connect a 20-amp fused jumper wire from the battery positive voltage terminal on the vehicle harness side of the ignition switch electrical connector to the corresponding battery positive voltage terminal on the ignition switch. Refer to Using Fused Jumper Wires in Wiring Systems.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 1 voltage circuit of the ignition relay at 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 23  Go to Step 33 
23
  1. Turn OFF the ignition.
  2. Connect the ignition switch electrical connector.
  3. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnect/Connect Procedure in Engine Electrical.
  4. Disconnect the underhood fuse block electrical connector that contains the ignition 1 voltage circuit from the ignition switch to the ignition relay.
  5. Connect the negative battery cable to the battery.
  6. Turn ON the ignition, with the engine OFF.
  7. Probe the ignition 1 voltage circuit between the ignition switch and the underhood fuse block 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 34  Go to Step 30 
24
  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 26  Go to Step 25 
25
  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnect/Connect Procedure in Engine Electrical.
  3. Disconnect the underhood fuse block electrical connectors.
  4. Test the coil ground circuit 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 35  Go to Step 34 
26
  1. Turn OFF the ignition.
  2. Connect a 20-amp fused jumper wire from the battery positive voltage circuit terminal at the underhood fuse block to the relay load circuit at the underhood fuse block. 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:
Does the test lamp illuminate on at least one test point of each fuse?		 Go to Step 27  Go to Step 34 
27 Test for an intermittent and for a poor connection at the underhood fuse block ignition relay location. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Did you find a condition?		 Go to Step 34  Go to Step 32 
28 Repair the short to ground in the battery positive voltage circuit between the underhood fuse block and the ignition switch. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 35  -
29 Repair the short to ground in the ignition 1 voltage circuit between the ignition switch and the underhood fuse block. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 35  -
30 Repair the high resistance or an open in the ignition 1 voltage circuit between the ignition switch and the underhood fuse block. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 35  -
31 Repair the short to battery positive voltage in the ignition 1 voltage circuit between the ignition switch and the underhood fuse block. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 35  -
32 Replace the ignition relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems.
Did you complete the replacement?		 Go to Step 35  -
33 Replace the ignition switch. Refer to Ignition Switch Replacement in Steering Wheel and Column.
Did you complete the replacement?		 Go to Step 35  -
34 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 35  -
35
  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 36  Go to Engine Cranks but Does Not Run 
36
  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
scientia non olet · About LEMON Manuals