Main Relay

oI5:

MAIN RELAY

NOTE: For a description of how the main relay works, continue at "Relays" at "Computers and Control Systems/Description and Operation". Relays

Check it's operation as follows:
1. Turn the ignition switch to the DRIVE position and measure the voltage across pin 2 of the idle air control valve, for instance, and ground, or across pin 3 of the mass air flow sensor and ground, to check whether the relay has been energized.

If current is present, the relay is OK if it also releases about five seconds after the ignition has been switched off.
If no current is present, continue with step 2.

2. Lower the relay holder under the dashboard and connect a jumper lead between ground and pin 85 of the relay.
Check whether the relay has been energized. To do this, check whether current is present on pin 87 of the relay.

If the relay has been energized, proceed to step three.
If the relay has not been energized, check whether current is present on pins 86 and 30 of the relay from maxi-fuse 2.
If it is, remove the relay and measure the resistance across pins 85 and 86 of the relay coil. The correct resistance is about 60 Ohms.
If the resistance is NOT OK, change the relay.

3. Check the lead between pin 85 of the relay and pin 46 of the MOTRONIC control module for continuity.
With the ignition switch in the DRIVE position, also check whether current is supplied to pin 27 of the control module from fuse 17.

If it is, and the control module does not ground pin 46, continue at "Before Replacing Control Module" for further diagnostic instructions. Before Replacing A Control Module