Kdeman1

My basic question is can the isolation relay cause one headlamp to fail? One of my headlamps works, well the other does not. I tried swapping the relays which did not fix the problem. Now I am hoping it is the isolation relay. The motor doesn't seem to run at all on the passager side

ccrazor

The isolation relay is only used (through its normally closed contacts) to close the headlight. If the wiring is the same as my 84, both lights get power from fusible links to open the headlight doors..

Cliff Harris

One test you can do is to open the headlight with the **** and then turn on the ignition. That should cause the headlight to close if everything is OK.

ccrazor

Cliff, for this to work you need to disconnect the motor first or it will provide power to close the door. You would need to switch the light sw. on, turn the ****, then turn the light switch off. If the door closes then the motor and that part of the system is ok..

Kdeman1

If I pulled my isolation relay and nothing seemed to Change does this point to a bad isolation relay? The one headlight continued to operate as normal

ccrazor

As I stated in post #2 the isolation relay has nothing to do with the door opening. Check for 12v on the red wire going to the relay for the door. If it is open then you need a new fusible link..