Tail Light relay ??

[Lazerbeans]

I have a relay to the right of the steering wheel, just under the dash, that buzzes key on until you turn the running lights on. All my lights up front work, but only the sidemarker and tag lights work on the back. The tail light bulbs don't light with hazards, turn signal, or brakes. I did check the taillights, I have one that's out, but the other shows conductivity or a complete circuit when check with a volt meter. Did switch sides, so no power to each. I get 11.03-11.13 to the 85-86 terminals when the headlights are on, but basically none when they are off. I register about .10 a volt when I press the brake pedal or use the turn signals. And I blew the fuse to the tail lights, and then turning the headlights on, does not stop the buzzing.

SO I know that the buzzing is a possible sign that the relay is bad OR there's not enough voltage getting to it. So my question which is it? Bad relay or bad juice to it, some how? Any ideas, experience or better yet wire diagrams?

[85crownHPP]

What year panther is it?
The brake lights and rear turn/hazard have their own special circuit that goes through the turn signal switch (multi-function switch if it is 1990+). This is how it lets the rear turn signals work if you have your foot on the brake. The 90+ ones do like to go bad in strange ways...
I would ask (if you had a newer panther) if it could be the LCM making noise, but it sound like you are talking about a common Bosh style relay if it has terminals labeled 85-86.
I didn't think any panther ever got that kind of relay for lighting, unless could it be part of a tow package or aftermarket?

[gadget73]

the tow package relays are in the trunk though. They also operate sort of independant of the rest of it. They only feed power to the trailer light harness. The in-car lights operate exactly the same as on a non-tow car. Not sure what might be to the right of the steering wheel unless its the low oil level relay maybe?


sounds like you have an open ground somewhere. If you have positive voltage but no light, thats about the only explanation. Not sure exactly where all the grounds are in the trunk, but I want to say at least one of them is right near the trunk hinge area where all the wiring feeds in.

[Lazerbeans]

The car is a 1990 Crown vic, ex-police. It is a common relay; F0AB-14B193AB. It does look stock, there's a spot on the dash frame. I did check between 85-86 with voltage and it does click. But from what I understand, that just tells me it closes the circuit, but not if it conducts electricity correctly.

[Lazerbeans]

Ok, I am dense, and don't know how many bulbs there is in the tail lights. I have been working on the rear bumper/trunk area and tucked all the wire back into the trunk. I was working with it in mostly direct sunlight. So I have both braided ground straps broken in the trunk. I happened to reconnect one in my semi-dark garage and realized my mistake. SO the turn signals, and running lights do work. That relay appears to be to the auto delay. If I turn it off, it buzzes, turn it on, it stops and everything appears to be fine. Though it leaves the markers on while its on. I didn't even know it functioned, let alone exactly how. Are the marker/running light supposed to stay on, with the ignition on or off until it times out?

Again, distracted, I got ahead of myself.

[gadget73]

if you have autolamps, the headlights and running lights should stay on until the delay times out. I want to say that uses a specific and odd relay though. No idea where it lives. If its not an auto lamp car, you won't have the delay adjustment knob behind the headlight knob.

[Lazerbeans]

I do have the adjustment knob behind the headlight knob. And I assume that its a relay for the auto lamp because it buzzes when you switch it off. As silly as it sounds I never looked twice at it, so didn't even knew it worked. Still feel dumb as hell for over looking that; something that simple. Goes to show, make sure your focus is completely on your task, and your never too experienced to make really stupid mistakes.

Thanks for the help guys

[GM_Guy]

Relays should not buzz when they get deenergized. You need to look for more wiring faults causing a backfeed through the relay.
Take a picture looking up at the relay so we can see where it is in relation to everything else. If it is stock, somebody will recognize it.

Have you removed the relay to see what no longer works? Being an old cop car, it could be from some removed equipment (open wires, hence the buzzing you hear when it tries to turn off) and may not even be needed.

Alex.

[gadget73]

Very true. Ford usually didn't use standard Bosch relays back then. Most of it were those goofy Ford-specific relays.

[Lazerbeans]

I have been working with the car more, and find out a bit more. Its some how associated with the auto lamp. If I turn the auto lamp off, it buzzes, or if the ignition is in the accessory position. But if the auto lamp is on, and also the ignition is on it doesn't buzz. And if its still in auto-delay, and I turn it to accessory after being ignition on, it wont buzz until the auto-delay turns off. However in the process of working with the tach, I popped the radio fuse, and it stop buzzing until I replaced the fuse. Also the brake lights stopped working due to the brake switch contacts being corroded, so its been a electrical headache. LOL. But all lights run, and the buzzing goes away if I leave the auto-delay on, so no sweat.

Its a ford relay because its has their number on it; F0AB-14B193AB. From what I understand when a relay gets "weak" it will buzz because there's not enough current to close the circuit, or the switch isn't right due to the coils being damaged. So it WILL click and whatnot, but still not carry the right amount of current. So I figure maybe until you run strong current through, either the auto-delay or headlight current, its not completely switching, therefore buzzing.