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Old 03-01-2005, 01:21 PM   #1
2 old 2 learn
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Default Help headlights won't open

Hey ya'll I am brand new here so take it easy on me till I get warmed up some. I have just bought my 2nd vette.I used to have a 73 for about 5 yrs and had to sell it a while back.I now own a 1994 roadster. But heres my thing.I was changing the upper rear radiator hose and doing some general cleaning under the hood because it was just plain nasy under there.And when I got it back together I was backing out of the garage and the headlight buckets won't come up.The parking lights come on when I turn on the switch but the headlights wont open or turn on.I looked at the fuse panel under the hood and they are ok and the fuse panel inside the car and saw nothing there for the headlights.But I have to drive to work tonight and I have no headlights HELP........
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Old 03-01-2005, 01:44 PM   #2
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Welcome, you've picked a good one to start with.

There is no circuit breaker for headlights. The switch itself is a self resetting circuit breaker. It is always hot. It routes power to the dimmer portion of the switch and also to the Headlight Control Module (a solid state circuit).

I believe you need to resolve a headlight motor issue as they will not energize until the circuit is energized.

Looking at the schematics, power is only routed to the lamps once the motor hits the fully deployed position in which it makes a ground.

Does the motor's run at all? Do they just not flip but the motor runs?

You may want to rotate them manually open using the **** on the top of the motor assembly. Do not push on the buckets to open or close them. It will damage the motor.

If you can rotate it up, then see if the light will turn on via the switch position.

If the motors are running but not deploying the headlamp, you may have an issue with the bushing in the motor assembly. Its an inexpensive fix, takes a couple hours though as you have to totally disassemble the motor. The whole headlamp assembly comes out after disconnecting the electrical connection and removing four bolts. You'll need to remove the cover first by half rotating it there are screws on each side of the cover. Once out you'll place it on a table for disasembly. Instructions provided with the bushing kit. Under $10. If that is not the issue, then the motor could be shot and needs replacing.

The troubleshooting is quite detailed, you probably should immediately invest in a set of service manuals from Helms (ONLY).
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Old 03-01-2005, 05:04 PM   #3
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Jet Jockey explained it well, If it is the bushings inside the gear, I have pictures and decent instructions from Corvette Fever for you. I took the pictures on my workbench when doing both sides. It may be uncommon for both gears on each side to go out at the same time though.
There are two separate circuits for the lights and the motor. Need info, write: vinterrv@aol.com
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Old 03-01-2005, 05:21 PM   #4
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Hey thanks for the reply.The switch when tuned to the first position which is the parking lights ingauges.But when turned on to the headlight position does nothing.The lights don't come on and the buckets don't try to turn or anything.It worked fine untill I was replacing the upper radiator hose.I did clean some of the covers and alluminum intake and the jacket that holds the therostat.I also replaced the bulb that burnt out on the interior hood light.But it was fine and worked strong up to that point.I was hoping it was just a minor thing I could look for to see if I unplugged a switch or some thing.
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Old 03-01-2005, 06:03 PM   #5
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I went out and opened the headlights manually and in the fully opened position the lights still do not come on?????Any help will be appreciated
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Old 03-01-2005, 06:04 PM   #6
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Can this be a ground problem?Is the a ground wire some where that I should check?
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Old 03-01-2005, 07:06 PM   #7
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I just got home from work. Just to let you know we are monitoring your feedback. So from what your saying is when the switch is placed in the 'lamp' position absolutely nothing happens. The motors don't run at all.

The write up to run some test is a bit lengthy so give me just a bit and I'll try to run you through it. Without doing any further fault isolation, my suspicion is either a ground or a switch fault. We can isolate that with the diagnostics.

Do you have a test light for 12v or a DVM? You'll need one. Are you rather proficient in following schematics? If so I can also provide some images of the charts/schematics.

Boatman is pretty much on with the notion that both failing simultaneously is pretty rare.

If everything was fine before you started the cleaning process, how did you do this cleaning? Using rags and cleaners or did you use a hose with water? Can be a little more detailed on what you did there. I just want to have a clearer image of what exactly was done in that we may be able to trace it down based on that.

I'll wait for your responses and in the mean time start a write up. I know you mentioned you need it to drive to work at night. So is this an urgent thing to happen this evening or do you have some breathing time? OR alternate vehicle just in case?
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Old 03-01-2005, 07:24 PM   #8
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Hi I was cleaning by just wiping things dowm with a towel after I changed the hose.It was a towel with some oil on it from use from before on some thing but not saturated by no means just enough to get the grime off the hoses and parts.I did use a wire brush on some of the parts like the control ark and on the the shocks and the thermostat housing.But really no water as like in taking a hose to it.I did run the lights out by hand tried that but its the same.No noise from the motors at all but the other lights came on as before.The fogs the parking the side markers and the parking lights.They are all fine.I looked over the wires to see if there was any breaks but I have not been able to find any thing. I do have a little time I called in and told them I was having car trouble. Its can't be much.As i said I just pulled into the garage and changed the hose and it wasn't blowing antifreeze or anything.It was a small hole.I did lose about 1 or 2 cups of antifreeze when I pul;led the old hose off but nothjing that would have gotten into the motors.Unfortunatly I don't have a 12 volt tester though.I have one that I check my household wiring with where I push it into the wall plugs and it lights up when hot but thats about it.
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Old 03-01-2005, 08:10 PM   #9
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Hey jet jockey I found a ride into work so I have to go.If you can think of anything that might help I will get back on when I get home and check.Or my e-mail is tkfields1@msn.com I sure do appreciate all the help from both you and boatman.If there is ever anything I can do please feel free to send me a note.I will get back with you as soon as i can.My ride is blowing the horn as we speak.Thanks again for everything and send me a note if you think of anything .i will be working on it again when I get home.Cause Its my work car right now.
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Old 03-01-2005, 08:14 PM   #10
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Ok good, it doesn't sound like "cleaning" has anything to do with it. Before I get to the meat of things, you did remember to bleed the coolant system after replacing the hose and topping off the surge tank? If not, there are two bleed screws one on the thermostat housing and one on the throttle body. With a cool engine, open your surge tank (firewall passenger side) make sure its topped off. Tuck a few towels/rags in around the bleed screws to capture the coolant and protect the opti-spark. Open the bleed screw one at a time until the air purges and a steady flow of coolant. It happens fairly quickly. Tighten and do the other. Re-top off the coolant. Start the engine with the cap off the surge tank, and monitor the temp as the engine comes up to temp about 190 or so. You'll see the thermostat open and flow begin in the surge tank. If the level drops down top it off. Once the temp is stable at 190 or so, and the coolant stays level. Shut it off, and secure the cap.

I'll be back with the headlight info...
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Old 03-01-2005, 08:16 PM   #11
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That's actually good news because this will take some time. Its quite detailed. If you can stop and pickup a test light at the parts store and/or borrow-get a DVM. Your going to need it.
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Old 03-01-2005, 08:19 PM   #12
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The headlight switch gets 12 volts from the 60 amp (Exterior Lighting) fuse located at the Underhood fuse block #2. It's located in front of the battery attached to the wheel well housing. If your horn works, the fuse is good.

When the switch is placed in the Head light position, 12 volts is supplied to the headlight control module located in front of the driver side wheel well housing. This activates the head light buckets.

At the same time 12 volts is also supplied to the headlight bulbs.

Since both the headlight buckets and headlight bulbs do not operate, the only thing that could be wrong is a bad fuse, bad head light switch, or the connector on the back of the headlight switch is not making good contact with the head light switch.

If you had a volt meter you would need to check on the back of the headlight connector for 12 volts on the red wire coming from the 60 amp fuse (Hot at all times) and 12 volts on the Yellow wire coming out of the Headlight switch when the switch is in the Head position. No 12 volts on the yellow wire indicates the head light switch is bad.

The headlight switch is easy to access.
Disconnect the negative battery terminal.
Remove the 4 screws holding the black bezel surrounding the cluster. Pull the bezel towards the steering wheel. You don't have to remove it.
Then remove the black plastic cover on the side of the driverside dash. This will expose the bolts holding the headlight switch. Desconnect the plug on the back of the headlight switch. On the connector one of the wires will be a large gage red wire. With a paper clip or heavy gage wire jump that wire to the Yellow wire.

Reconnect the negative terminal. If the headlights come on and the head light buckets move. The headlight switch is bad.

Last edited by Hooked on Vettes; 03-01-2005 at 08:55 PM.
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Old 03-01-2005, 08:54 PM   #13
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Think there is a difference between 93 and 94? I wonder because looking at the schematic I see the under hoot fuse block #2 with a 30 amp for each hdlp motor. I don't see a 60amp fuse. I'm wondering if there is a difference?

Likewise, looking at the switch schematic I only see two 'K' a yellow and 'J' a white wire. It looks like the yellow passes through the dimmer circuit and on to the control module. The logic there seems to indicate that when in the Head position yellow is hot and when in the Off position white is hot. Off hot energizes the motors to close and Head energizes the motors and then routes power to the lamps.

It sounds like you've had the switch out before so that maybe a quicker approach than standard troubleshooting. Plus I'm looking at the schematic not the real switch.

I'd try this approach and see what happens. Sounds good to me.
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Old 03-01-2005, 09:16 PM   #14
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If you have the Helms book #2 for a 93, look at page 8A-10-2.

Look at the fuse Exterior Lighting. (60 amp) Under Hood Fuse Block #2.

Follow the circuit #1446 Red wire. It goes to the Light Switch and I/P Fuse block and supplies power for the Stop/Haz, Tail Lamp and Horn Fuse. So if the horn works, the 60 amp Exterior Lighting fuse is good.

Go to page 8A -100-0

Look at the Headlight switch top right.
12 Volts from the Red wire comes into the Headlight switch where it says Hot at all times.
When the Headlight switch is placed in the Head position, 12 volts comes out of Circuit 10 Yellow wire and provides 12 volts to the Headlight Control Module for the headlight motors and 12 volts to the Head light Dimmer switch which passes the 12 volts to the Headlight lamps.

Since the head lights and headlight motors don't work, the only thing common is the 12 volts that comes from the Yellow wire from the headlight switch.

I'm not sure if 93 and 94 have the exact same schematic/circuitry but looking at the schematic for lighting and head lamp motor, they are very similar.
I do notice the color code for the wires are the same but some of the circuit numbers are different.

Last edited by Hooked on Vettes; 03-01-2005 at 09:26 PM.
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Old 03-01-2005, 09:18 PM   #15
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I would reccomend having a can of contact cleaner and a tube of di-electric grease on hand. When you take a connection apart, clean it then coat it with dielectric grease. This way, it's more resistant to water.
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Old 03-01-2005, 09:32 PM   #16
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Quote:
Originally Posted by Hooked on Vettes
If you have the Helms book #2 for a 93, look at page 8A-10-2.
Ok yep I see that. So 1446 from the 60 amp routes power to the square block that says Hot at all times in the upper left corner of the schematic light switch?

So he could test the red wire 1446 coming in with a DVM and it should be providing 12V to the switch if the 60amp is good. And then putting a jumper between the red and yellow would bypass the switch and if it energizes the circuit would mean the switch is bad?

Is there any risk jumping it like that with voltage going to the control module or is a relative safe test?
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Old 03-01-2005, 10:02 PM   #17
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If the horn works the 60 amp fuse is good.

Yes he would need to test the Red wire for 12 volts to make sure it's getting to the light switch connector.

He needs to use a jumper wire at least the same gage or bigger than the yellow wire. He could also put a 30 amp fuse in series with the wire so if he connect the jumper to the wrong wire, the fuse would blow and not melt the wire.

If he jumps red to yellow at the connector when it's disconnected from the light switch and the headlights come on and the doors open, the switch is bad.

I didn't mean to hijack the post but he said he needed the car.
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Old 03-01-2005, 10:11 PM   #18
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I don't think it was hijacked at all. This is all good information. I would have simply restated the troubleshooting steps to help him arrive at the same conclusion. Yours took much less typing. I'm sure he'll have a lot to read when he gets home. He definitely needs a DVM. I think that the switch is either defective or has a bad/corroded connection.
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Old 03-03-2005, 06:24 PM   #19
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Hey yall I want to start out by saying thanks to all that posted for me it was very kind.I did jump the yellow wire with the red on the back of the switch and they came out and on.But I cannot figure out how to get the plug to release from the back nor how to remove the switch from the panel.I have it hanging but I am afraid that I am about to break it.Any clues?
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Old 03-03-2005, 07:57 PM   #20
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I emailed you a picture of the two connectors to your msn account.
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Old 03-03-2005, 07:57 PM
 
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