Main Relay Circuit Diagnosis. Chevrolet Optra 2005

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2005 🢒 Optra 🢒 Engine 🢒 Engine Controls - 1.6L (L91) 🢒 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 engine fuse block fuse Ef11. The electronic ignition (EI) system ignition coil is supplied voltage through the engine fuse block fuse Ef11. The fuel injectors are supplied voltage through the engine fuse block fuse Ef11.

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	Turn the ignition OFF. Disconnect the engine fuse block fuse Ef11. Turn the ignition ON. With a test light connected to the ground, probe the fuse terminals nearest the main relay for fuse Ef11. Is the light ON at both terminals?	--	System OK	Go to Step 2
2	Is the light ON at only 1 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 Ef11 as needed. Is the repair complete?	--	System OK	--
4	Turn the ignition OFF. Remove the main relay. Turn the ignition ON. With a test light connected to the ground, probe the main relay terminals 85 and 87. Is the light ON at both terminals?	--	Go to Step 6	Go to Step 5
5	Turn the ignition OFF. Measure the resistance between terminal 85 of the main relay and ground. Is the resistance within the specified value?	0 ohms	Go to Step 7	Go to Step 6
6	Repair open circuit. Is the repair complete?	--	System OK	--
7	Replace the main relay. Refer to Relay Replacement in Wiring Systems. Is the replacement complete?	--	System OK	--