1989 foglight issues

[fordsho8991]

If I have my fogs on long enough (about half hour or so), my headlights will start flickering on and off until I shut the fogs off. I'm using the stock wattage h3 bulbs (55 watt). I originally had put the blazers in and it did the same thing. Thinking it might have been them, I went and got the oem fogs and bulbs, only to have the same issue. I already burned up one headlamp relay in the turn signal/wiper/high beam stalk, and I dont want to do it again. I just can't figure out why it's doing this with all stock fog components. I did put nokya arctic white 80/100 watt headlight bulbs in, could this be a possibility? They work fine without the fogs on and I have had no issues with them otherwise. Thanks for any info.

-Ken

 

[NotSoSlowSHO]

The '89 fog and headlamp circuit is known to have problems.

All of the current goes through the MFS (multi function switch) on the column.

If you are having flickering, or brown outs, then the MFS is probably due for replacement.

After replacing it, bypass the MFS for the for lamps, install a relay, and call it a day. The MFS does fine with just the headlamps. But the fogs really need to be on another circuit.

 

[fordsho8991]

Thanks for the info notsoslow. Do you know how I would go about bypassing the mfs for the fogs? I know how to install a relay, but I'm not well versed enough in the electrical system to know how to bypass it.

 

[NotSoSlowSHO]

You will need to do some testing, with a multimeter... as I dont remember which wires are which.

You will have to pull the fog lamp switch. From there, find what incoming 12 lead you have. The existing one goes through the MFS. So you need to cut that wire, and find another 12v source to power the switch and relay. You will also have to find a solid 12v source (15 or 20AMP) to tie the fog lamps to the relay.