GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2005 🢒 Wave 🢒 Engine 🢒 Engine Controls - 1.2L 🢒 Main Relay Circuit Diagnosis

Circuit Description

When the ignition is turned ON or to the START position, the main relay is energized. The main relay then supplies voltage to the electronic ignition (EI) system ignition coil, evaporative emission (EVAP) canister purge solenoid, and oxygen sensors. The fuel injectors are also supplied voltage through the main relay.

Diagnostic Aids
    • An intermittent condition may be caused by a poor connection, rubbed through wire insulation, or a broken wire inside the insulation.
    • A faulty main relay will cause a no-start condition. There will be no voltage supplied to the EI system ignition coil or the fuel injectors. Without voltage supplied to these components, they will not operate.

Step

Action

Values

Yes

No

1
  1. Turn the ignition OFF.
  2. Disconnect the engine fuse block fuse Ef2.
  3. Turn the ignition ON.
  4. With a test light connected to the ground, probe the fuse terminals nearest the main relay for fuse Ef2.

Is the light ON at both terminal?

--

System OK

Go to Step 2

2

Is the light ON at only one terminal?

--

Go to Step 3

Go to Step 4

3

Repair the open in the wiring between the main relay connector terminal 87 and the fuse Ef2.

Did you complete the repair?

--

System OK

--

4
  1. Turn the ignition OFF.
  2. Remove the main relay.
  3. Turn the ignition ON.
  4. With a test light connected to the ground, probe the main relay terminals 86 and 87.

Is the light ON at both terminals?

--

Go to Step 6

Go to Step 5

5
  1. Turn the ignition OFF.
  2. Measure the resistance between terminal 86 of the main relay and ground.

Is the resistance equal to the specified value?

0 ohms

Go to Step 7

Go to Step 6

6

Repair the open circuit.

Did you complete the repair?

--

System OK

--

7

Replace the main relay.

Did you complete the replacement?

--

System OK

--