GM Service Manual Online
For 1990-2009 cars only

Object Number: 383998  Size: MF
Engine Controls Component Views
Ignition Coil/Module Cylinders 1 and 3
OBD II Symbol Description Notice

Circuit Description

The IGN relay supplies a voltage to various fuses. The IGN relay is located in the underhood Electrical Center. The following components are powered by the IGN relay:

    • Injectors/Ignition coils
    • Throttle Actuator Control (TAC) module
    • Transmission
    • A/C system
    • EVAP solenoid
    • MAF sensor
    • AIR pump relay and AIR solenoid
    • TCC/Cruise and Extended Travel brake switches

Diagnostic Aids

Important: 

   • Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.
   • For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616 . Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Wiring Systems.

Ignition (IGN) Relay Underhood Electrical Center Terminal Identification

Front of Vehicle

Left Side of Vehicle

Ignition

B+

Right Side of Vehicle

Load

Ground

For an intermittent condition refer to Symptoms .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Removes the underhood electrical center and inspects the circuits that are supplied a voltage by the IGN relay.

  2. This step tests the ignition relay ground circuit.

  3. This step isolates the circuit from the IGN relay . All of the circuits at the relay are good if the test lamp illuminates.

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Turn OFF the ignition.
  2. Remove the underhood electrical center cover.
  3. Remove the IGN relay.
  4. Probe the B+ feed circuit to the IGN relay harness terminal with a test lamp J 35616-200 connected to a ground. Refer to Diagnostic Aids for the IGN relay terminal identification.

Does the test lamp illuminate?

--

Go to Step 3

Go to Step 8

3

  1. Turn ON the ignition leaving the engine OFF.
  2. Probe the ignition feed circuit to the IGN relay harness terminal with a test lamp J 35616-200 connected to a ground. Refer to Diagnostic Aids for the IGN relay terminal identification.

Does the test lamp illuminate?

--

Go to Step 4

Go to Step 9

4

Probe the IGN relay ground circuit at the underhood electrical center using the test lamp J 35616-200 connected to B+. Refer to Diagnostic Aids for terminal identification.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 10

5

  1. Turn OFF the ignition.
  2. Jumper the IGN relay B+ feed circuit and the IGN relay load circuit together using a fused jumper wire. Refer to Diagnostic Aids for the IGN relay terminal identification.
  3. Probe the fuses for the following components with a test lamp J 35616-200 connected to a ground.
  4. • A/C
    • INJR1
    • INJR2
    • THROT CONT
    • ENG IGN1

Does the test lamp illuminate for each of the circuits?

--

Go to Step 6

Go to Step 11

6

Inspect for poor connections for the IGN relay at the underhood electrical center. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find a poor connection?

--

Go to Step 11

Go to Step 7

7

Replace the IGN relay.

Is the action complete?

--

System OK

--

8

Repair the open B+ supply to the IGN relay. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

System OK

--

9

Repair the ignition feed circuit to the IGN relay. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

System OK

--

10

Repair the open ground circuit for the IGN relay. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

System OK

--

11

Replace the Underhood Electrical Center.

Is the action complete?

--

System OK

--