I have a 97 F150 with Pilot HIDs on it. The other day both of my headlights went out and I turned them off then back on it was fine. Later that day they went off again and would not come back on. If I switch my turn signal lever to high beam they will work but both lights on the low beams don't work. I've checked the fuses under the dash and also one fuse under the hood. I would think that it would be really odd for either both the bulbs to go out at the same time or both of the ballast to go out at the same time. I put a volt meter on the output wire of the ballast and get 0 when I put it on the wires going to the ballast I'm only getting .325 volts. I have my lights hooked directly to my battery with a relay on it, I have tried changing that relay and also looked at the electrical from the relay to the ballasts and nothing seems to be wrong and the relay clicks when I turn the lights on and off. Suggestions anyone?

 

You checked all the fuses in the cab, why ?

There are only 2 you need to be concerned about in the cab, Left low beam, and right low beam.

Check both of these fuses again with a meter, to a know good ground ( test it against the cigar lighter, or one of the power points ).

Turn the main headlamp switch to the headlamp position, and pull back on the MFS, to ensure you are in the low beam mode. These are fuses 26 & 28.

With the fuse still in the slot, check for voltage to both side of the fuse.





If you have voltage on both side of both fuses, time to check the INPUT to the ballast, to make sure the relay, and the fuse to the relay is good.

Next test the input to the ballast from the factory headlamp wiring, to make sure the ballast sees the trigger voltage.

The Ballast output voltage could be in the KV range with HIDs ( like a florescent light fixture, low current, high voltage converted from line by the ballast ).
You could have shellacked your meter testing the output of the ballast, depending on the meter. My Fluke 23 only goes to 1000 V DC, yours could be higher ( printed on the meter, either on the back, or next to the red probe input ).

 

Sorry I didn't make myself clear, I didn't check all of the fuses just 26 & 28, they were fine. Also like I said the input is reading like .325 volts. My wiring is similar to this


but I only have my low beam hooked up that way so it may be something with that. Like I said, I've changed the relay that I added in the schematic above and I have also checked the ground and fuse and nothing. I may try wiring it back to how it was originally but don't want to do that if It might be something that would be easier to fix.

 

So you have 12 V on both sides fo the fuse

Input to the ballast from where ?
The low beams or from the power to the ballast.

What is the forced low beam switch in the diagram for ?

Why do you have a relay from the low beam, to the trigger input of the ballast ?

If you know that you have voltage from the fuse, is it making it to the ballast ?

What do you mean nothing ? If there is no power from the relay or the fuse for the relay, something is wrong there.

 

yes
from 87 on the relay the wire runs and has a connector on the end that plugs into the ballast, I checked the voltage at the connector.
You can ignore the green wiring, that doesn't apply to me, just the blue, that's the only changes I made.
Originally I didn't have the HIDs when I rewired to the schematic. I guess you could say I was experimenting and the it worked so I just left it, not there was a huge difference in the headlight brightness.
That's what I was saying or atleast failed at saying, heh. The power going to the ballast is only reading .325v.

I meant nothing as in no problems there, power is going through.

 

The relay that is triggered from by low beam, and you don't have power from the Pin #30 ( battery ) to pin #87.

If you pull the relay out of the socket, and jumper 30 to 87 what happens ?

A. The HIDs work, and you don't have +12 at 85, with the headlamp on low beam

B. Pin 86 does not have ground on it

C. The fuse from the battery to pin 30 is bad.

This is assuming the ballast does not have a trigger wire also hooked to the low beam out of one of the 2 low beam fuses.

 

I haven't tried to jump those yet. I know I could basically go down the line and eliminate things that could be the problem. Just hard to work on a vehicle when you only have about 30 mins before dark after getting off of work. Just trying to get some more ideas so I can have an exact plan and check what I need quickly. If not I'll just wait til the weekend and go through everything.