I just checked the bulbs for the underhood lights because they weren't working. The bulbs were shot, but I checked for voltage just to be sure, and the voltage was fine. I went and bought new bulbs, and put one in and it sparked and now doesn't work. The other side doesn't work either... I checked the fuse and it was fine. And I no longer have voltage going to either one. What the hell!?!

Is there a nother fuse I don't know about or some trick to getting these to work?

 

Were the bulbs the correct ones you installed? If you don't have voltage at the socket trace the wires.....there are connectors located down by the radiator area.

 

Each lamp has it's own connector. The left side lamp connector is behind the evap canister. The right side one is below the two wire connectors by the RH cornering lamp housing.

Each lamp has a mercury switch that controls the light. I would check each one for continunity even though they are separate.

According to my FSM, power for these lights come from the 15A fuse marked Ctsy/Clk on the fuse panel (passengers side edge of dash) It will be the 2nd from left on the top row. Is that the one you replaced??

 

No, I never replaced the fuse, because the fuse never blew, and Ctsy/Clk was the one I checked. The connectors are connected, and like I said I had voltage where the bulbs go just before I replaced the bulbs... After I replaced them, no more voltage. Also the first bulb I installed sparked and light up for a micro second, then nothing. That made me think it was a fuse but the fuse is fine.

I am PUZZLED...!

How do I check themercury switch?

By the way I just bougtht the car a few months ago and the old owner said the light housings and all that were new.

 

Over in the left front fender well by the vac cannister is a fuse in a weatherpack fitting. This is for my 95, not sure what year you are dealing with.

 

I have an 87. But I will check, and I just thought about checking the voltage at the connector also. I will get back if I find anything out!

 

The mercury switch is a capsule with two leads and a blob of the liquid metal. If you ever looked inside a common honeywell furnace thermostat there are a couple of them in there.

Tipped one way the switch will ohm a short, the other way infinity.

 

If the bulb lit up for a brief second, then went out, I would make sure it is a 12 volt bulb.
If there is no volts, then you need to find out if there is a fusible link that has been over currented.

 

The only other possibility is a broken/shorted ground wire. Looking at the wiring schematics, the lamps get grounded at the wires that attach to the front frame rail just above each horn. On my 87, there is a single ground wire above the left horn and two wires above the right horn. But all sorts of other electrical stuff in the nose gets grounded there; horns, fog lights, turn/park lights, cornering lights as examples.

The mercury switches are just small modules below where the bulbs are held by the clips. The switches close the ground side of the circuit when the hood is raised. You can test them with an Ohm meter. Open the hood, remove the bulb and check for continunity between the two spring clamps of the switch. If you get 0 Ohms, they are good.

You might try disconnecting the lamps at the connectors in the corner headlight bucket wells and see if voltage is present at the other side of the connectors. Since I had my 87, I have had to repair broken wires for both power and ground between the lamp and the connectors. It's possible that the spark you saw was enough to burn out a frayed chunk of the wiring. Check where the wires make a sharp turn. Wire that old can be pretty brittle.

aminnich- he has an 87 and they did not have a single inline fuse for the underhood lamps.

 

If the bulb lit up for a brief second, then went out, I would make sure it is a 12 volt bulb.
If there is no volts, then you need to find out if there is a fusible link that has been over currented.
and make sure the connectors at the corners of the hood have a valid ground. less that 5 ohms to ground.

 

I went out and checked for voltage at the connectors and there was none. It is too dark out now for me to see much else so I am going to wait until the morning to finish looking around.

It is going to be hard to find a break in the wires, they are all in a plastic shieth. Wouldn't you think if it was a ground problem other things might not be working either?

 

So I was kind of tracing wires today and there seems to be a little box on the front of the drivers side inner fender. It looks like I would have to take the inner fender out to get to the inside of the box. The wires for the under hood lights dont go directly to it, but wires from the same harness do. Anyone know whats in that box??

Anyone have the wiring diagram for the under hood lights? I looked in my service manual but section 8A seems to be missing!!

 

That box your describing houses the controls for the headlights.

 

Ok thanks, I'm gald I didn't tear into it!

I still need a wiring diagram if anyone has one for the under hood lights!?!

 

Anyone? Wiring Diagram for under hood lights?

 

I don't have the "manage attachments" feature available to me. I sent you a PM. I have a little info (diagram) in a pdf file I just made from the FSM supplement manual but can't attach it or show it in the forum.

 

Ok here is a snapshot of the diagram.....aint nothin' to it. Just 2 connectors, the head/parking switch, mercury switch and the lamp. You can troubleshoot it all day.....but turn the headlights or parking lights on and see if you get power back at the bulb socket first.

 

I uploaded an image to the below. Good luck

http://s436.photobucket.com/albums/q...hoodlights.gif

 

What is that cresent shaped break in between the underhood light and the junction labled S103? Does the cresent-break signify an in-line fuse, or a connection?

I had no power with the headlights or running lights on.

I know there is a connector for each underhood light. Is there a third connector where the 2 seprate lines meet?

 

Those are connectors....I'm not sure....the diagram doesn't show that if it does...I have my underhood lights disconnected (the plugs by the headlights)because those lights will kill your battery quick if the stay on from a stuck/failed /failing mercury switch...most people I know unplug them for the same reason.