This sounds weird even to me as I explain it. I have some auxiliary lighting using a module that has a cutoff switch. The cutoff switch is wired into the driver side low-beam wire, so when the low beams are active, it cuts the aux lighting. The cutoff works fine when the engine is off, but when running (and the voltage increases) the cutoff fails. I have 12.5V coming from the low beam wire with the engine on, which is a bit low. There is a hot wire coming off the battery cable and a switched power source, both of which are 12.5V with engine off, 14.0-14.3V with engine on. So I'm thinking the cutoff switch operates depending on the voltage differential, which is too high to fire it when the engine runs. If, when the engine is running, I apply the cutoff switch to the battery or any other terminal putting out over 13V, it works. If the engine is off, the headlight measures about 12V, the hot and switched power measures about 12.5V, and the kill switch works. Should I use a resistor to reduce power coming into the aux lighting module? Is there another way? Thanks for any replies.

 

Resistors don't limit voltage, they limit current. What you're saying doesn't seem to make sense. The module should simply consist of a relay. Which is most likely wired as so... (Pin 30 - 12V Source, Pin 87A - Switched 12V output to Aux lights, Pin 86 - 12V input from low beam wire to coil, and Pin 85 - Ground) A relay does not work on a differential, it's either on or off with an operating range of usually 9-16 volts.

It may work differently than this, but it seems unlikely bevause a relay is very simple, reliable,and cheap. No reason to get more elaborate.

Plus if they made this product to be used on a vehicle they would obviously make it to work fine on a normal vehicles running voltage (13.8-14.5) My guess is, there is something else going on here. What, I have no idea, it's definatly a weird problem. When you try this with the truck not running, is the key in the "run" position?

 

If the engine is not running, it works fine in whatever key position, or no keys at all. The module is a headlight flasher, running at about 15 amps. Yes, this problem is very strange and I can't explain any of it.

 

This module is one of the few approved for use on the Durango, so it definitely is compatible with the vehicle.

 

Do you have a link to the module? So I can see exactly what it is?

 

Thanks for trying to give me a hand. Here is a link to the Galls FS008 isolated headlight flasher:

http://galls.com/documents/FS008_Spe...pp_Flasher.pdf

Another 3 people I talked to at various electronic/automotive shops were mystified.

 

That module you showed me is for an emergency vehicle to make the headlights flash (Like a police car). How are you using this to control aux lighting??

Why not just use a relay?? I see no reason to use this device for what you're doing. Unless I'm missing something.

 

I said "auxiliary lighting" which was misleading, now that I think about it. I am using the flasher exactly as it was designed to be used, on a vehicle that needs flashing lights in the front. I just didn't want to get into it too much and have to field a bunch of questions like "Why do you need that?". Trust me, it's legal and I do need it. With all this trouble, I should have just used strobes or a lightbar. But I don't want the thing to look like a police vehicle, with all sorts of visible external lights.

 

Well in your first post you said when the low beam is on, the aux lights are cut, but in the directions, it's supposed to cut when the HIGH beams are on.

BTW, do you have day-time running lights?

 

The high beam cutoff is a built-in function, and that works. There is an additional, optional function whereby when the black wire is attached to a power source it triggers the "nighttime cutoff" when current is present. That needs to be teed into a light wire. That's what is not working as it should. This vehicle has no DRL. The only other thing the lights are attached to is the lock/unlock (headlights flash once) and the panic (horn honks, lights flash) relays.