MikeP84

I was wondering why the 86ish+ can turn on their fog lights with just the running/parking lights on, where as the 84s you have to have the headlights on. I have an 84 but I like how you can use the fog lights w/o headlights and wondered if its just my switch that's bad or if they changed something and if there was a way to wire it to work with just parking lights on.

Hot Rod Roy

GM decided that your way was better! To have the fog's with the parking lights in your '84, the headlight switch would need to be re-wired. It's not exactly easy to get to the headlight switch, but it can be done!

If you have the FSM (Factory Shop/Service Manual), the job is easier.

MikeP84

Yeah it was definitely a better idea to have the fogs work with parking lights and looks way better! Hmm darn, I was hoping that I could just replace the leadlight switch with one off an 86 and be good. Unfortunately I only have the one you can get from the parts stores. Any chance you know what wiring id have to do? I'd guess just wire the signal wire for the frogs from the second position to first pull position.

ex-x-fire

I put a link in your box.

MikeP84

Thanks!!

Cliff Harris

The '86 model has several unique wiring changes. For one thing, the fog lights do NOT ground through the headlight filaments. They have an independent ground. That makes it much easier to do a HID or LED headlight modification.

This thread has a lot of information on this situation:

https://www.corvetteforum.com/forums...-solution.html

MikeP84

Thanks Cliff, I have read through some of this thread but I couldn't find it again. It seems like you and Circuit Doc. both have extensive knowledge about electrical systems and these cars. I would love to swap my lights out for LEDs but I just haven't gotten there yet. I was looking up replacement LED lights for the rear tail lights and other locations but I'm not sure if I can just buy and install them or if I have to do other work to make them function properly

Cliff Harris

What usually happens is that the LED lights take too little current. The flasher depends on the bulb current to work. Your lights will either blink very slowly or not at all (usually the latter). The solution is to buy an electronic flasher. They are available at any auto parts store.

MikeP84

Hmm interesting, I was not aware that they made an electronic flasher. Thought id have to wire up a 168 bulb like Circuit doc did (which is cool but not something id want to do)


So bc the interior lights don't have relays within their circuit, LED interior lights would work with no modification?

Cliff Harris

I have LED lamps in my instrument cluster. Theoretically they should work just like the incandescent bulbs, but in practice the dimming function doesn't work very well. The backlight circuit uses pulse width modulation to adjust the brightness of the lights. For some reason my LEDs don't work well with it.

MikeP84

Well I rarely run with them on low as they are pretty dim to start with but that is good to know they would at least power up with LEDs in there. I'm guessing that as they are turned down they start to flicker on and off? I know that my high efficient house light bulbs flicker and don't work very well when they are dimmed down.

whalepirot

LEDs may work with conventional dimmers, or not. I've done quite a lot of this at home and in the car, is show I know. there is an assortment of LED dimmers and every dimmer isn't necessarily compatible with any LED.

I hate LED headlights which are VERY directional (trait of all) and seem always aimed at my eyes!

The classic turn flasher signal employs an RC timing circuit, the resistance (load) being a variable with changed bulbs or proper grounding; why the flash rate varies accordingly. LEDs offer quite a different load to the circuit, so an electronic flasher, with internal timing circuit, doesn't rely on the car's wiring or bulb for flash interval. It's not, however, an easy component to access in a C4.

I re-wired (at the headlight switch) to power the fogs when only the parking lights are on. The wiring's quite simple: a matter of powering the triggering wire from the parking light-on, versus headlamp-on spade connector on the switch, which as Rod said, is a PITA to access.

While rarely used, years ago I replaced the fog bulbs with 55Wers; nice improvement.

To use fogs as DRLs, the trip wire (purple?) would operate from an ignition-ON source, via or not, the foglight switch.

MikeP84

When you say the car's wiring do you mean proper grounding? Well I some of the interior pulled apart right now as I'm doing a XFire to TPI swap so I have access.



ex-x-fire sent me a link so I know how to do it, just have to do it!

gerardvg

I can have the fog lights on without headlights on, only the park lights turned on. It has always been like that unless it was modified by someone before I got mine?
I have an 85 c4.

MikeP84

I think they changed it from my style in 84 to your style in 85. I didnt not know if 85 was like mine or not but I knew 86 was like yours

1993C4LT1

I have HID fogs from retrofitsource, they are 35 watt 5000k.

MikeP84

Mmmmm those babies look good!

1993C4LT1

Thanks! I'll see if I have a pic on how much light they put out. Oh, and to anyone wanting to buy them, 880 bulbs are the same as the 896 bulbs. I know the 91-96 use the 896 fog bulbs.

Cliff Harris

The 880 bulbs are 37 watts. You can upgrade to 882 bulbs at 50 watts. Just change the TAIL fuse to 15 amps. The wiring is quite capable of handling the extra current.