OK, the parking lights go on but the headlights don't. I noticed the other day that the lights came on after 5 min with the switch on, but now nothing.
Has anyone else had this problem? Any ideas?
More information needed to diagnosis the problem. Does the car have the Twilight Sentinel or the Guidematic unit? Either or both of these units can cause diagnostic problems. My initial feeling is that there is a poor ground wire that is causing the problem. The other thing that can cause this type of problem is the headlamp dimmer switch mounted on the floor. To check the dimmer switch, with the headlamps on, stomp on the switch a few times while someone else stands in front of the car observing. If they see a flicker, then the switch is bad. It also can be totally gone, and even this test won't determine this. I will hold out any further suggestions until you check out these suggestions and let us know what accessories are hooked to the headlamp circuit..... Junk...
If it does have a floor mounted dimmer switch, pull the carpet back and you will see the connector. Unplug the connector and run a jumper wire from the thickest wire, the 12 volt source , to one of the others. If the lights now work fix the melted connector or replace the dimmer switch.
I clicked the dimmer switch about 10 times and the lights finally came on. So it would seem that I need to replace the wires from the dimmer. Not sure how to do that but I will take a look tomorrow. The car does have the sentinel; I'm not sure what the guidematic is.
Thanks
For all participants that read this, I will explain both systems.
The Guidematic is the unit that automatically dims the headlamps when your car approaches other cars from the opposite direction and returns the headlights to bright when the cars pass. The Guidematic has had a few different names through the years and was originally know as Autronic. It first came out in the very early 1950's and has been refined through the year till now, almost all high end car manufacturers use it on their cars.
The Twilight Sentinel is the unit that turns the headlamps on at dusk and turns them on at daylight. It also has a delay feature that keeps the headlamps on for a short time after you stop the car and exit. This feature is designed to illuminate your way into the house.
Getting back to your problem, the wires and terminals in all probability are fine, but the headlamp floor dimmer switch will need to be replaced. I know this from your description of what happened after you used my testing method. This switch can be purchased at almost any auto parts store. Almost all GM cars for the past 30+ years have used the same switch. If your car has the Guidematic system installed on it, then the switch has one additional wire going to it. This additional wire is on the opposite side of the 3 pronged wire and is the over ride part of the system. You must install the proper switch to keep all functions working properly. I have posted the picture of the headlamp switch that has both functions. If your car has only one of these functions, then it will only have one marked on the headlamp switch. If a car has neither of these options, then the plate behind the switch is blank... Junk..
If you have automatic dimming headlamps, then that is the Guidematic system. You will need to replace only the dimmer switch. You will need to pull back the carpet to get to the switch. First, if your switch has a rubber cap on the top of it, pull that off. Then remove the plastic side panel, by removing the one Phillips head screw and pull it toward the rear of the car. If it doesn't come out easily, check to see if there are any other screws holding it. Once you have this panel off, then you will be able to easily pull back the carpet. Remove the two screws that hold the switch to the floor and then pull off the single wire first. That wire doesn't have a release terminal and should come off easily. The terminal with the three wires, you need to gently pull apart the clips on either side of the switch to release it. This is done with gentle finger pressure and requires no tools. Purchase a new switch at NAPA and reverse the removal instructions to install. The switch cost is $13.49 ...... the part number is ECHDS116..... you can view it on the NAPA website...... click here.......
Out of curiosity. does your car have both the Twilight Sentinel and the Guidematic or the Guidematic only??????
If the Twilight Sentinel doesn't work, it is a lot more involved in repairing it. Unless you are mechanically inclined and don't mind taking your car apart, I wouldn't attempt to repair that system. You can try to turn the dial behind the headlamp switch a few times and see if that wakes up the system. If not, then it will need the electronic module and the photo cell replaced. Both of these items came wrapped together, because they are a matched set. One without the other is worthless and they are both a real pain to install. I know because I have done this before........ like this past !!!!!! Junk.....
I know this is a old post and this is the problem I am having. I have the 4 wire system but the part number you gave is no longer valid. Do you have a new part number? Thanks.
Keep in mind on that old of a car, I've seen melted connectors which will act up the same way. It will be very apparent when you go to remove the plug on the dimmer switch. Usually the source wire will over time produce enough heat to melt the connector. In that case replace the dimmer switch and repair the melted connector by cutting the wire out of it and replacing the connector end to fit snuggly.
There is no engineering problem with the floor mounted dimmer switch. The melted plastic connectors are a result of the heat that is generated when a terminal developers high resistance. This high resistance is developed as a result of moisture that starts a corrosion problem. The moisture comes from both high humidity and the wet feet that get into the car and use the differ switch. In climates such as experienced in Arizona, where the humidity is low and the rainfall is infrequent, they don't have these problem usually. The other thing that causes high resistance in a circuit is arcing which is also a result of poor contact. This is the reason that all high end electronics use silver and gold terminals to eliminate these type of problems. I have a 1978 DeVille that came from Florida, and there is only one melted plastic terminal on the car. It is on the heater box, where it was subjected to water running onto it. The dimmer switch terminal is perfect. By the way, the dimmer switch design dates back to the 1950's, so that must be a testament to its ability to withstand abuse and still work properly. As far as switches on automobiles, the dimmer switch is one of the least replaced switch.... Junk..... defending the dimmer switches of the world.... :thumbsup:
I replaced the switch yesterday and all of the wires were fine. I haven't been driving the car to much so it's hard to say if it's a complete fix. Especially since for some unkown reason the lights started working again before replacing the switch!
I have the same problem and replaced the dimmer switch which cured the problem for a while (about a week) then one night after a gig at a club the headlights stopped working again. My car is a 76 CDV with sentinel and guidamtic auto dipping.
I intend to check the wiring and bridge some connectors to try and track the problem dto its root today with a volt tester. Does anyone think it might be the circuit breaker ?
This is obviuosly not an uncommon problem but a dangerous one when one is out away from home and darkness falls and only sidelights to drive on. This is a ticketable offence in most states and the cops will make you leave your car wherever they stop you !
Your car requires a special dimmer switch with an additional terminal on the opposite side of the 3 terminal connector. If you didn't get the proper one, then that will cause you problems, since the circuit isn't completed. To verify this condition, turn off the Guidematic and the Safety Sentinel. If the lights work, and you have used the correct dimmer switch, then the problem is one of these two units. If the circuit breaker trips and the headlamps go off, they will come back on once the breaker automatically resets. It could also be in the headlamp switch itself, but not as likely. Usually, when a headlamp switch is defective, it is more likely that it will be the dash lights that will stop working first. It is rare that there is ever a wiring problem with these circuits. Junk....
Thanks Junkman I looked at the new dimmer switch installed by my local mechanic and noticed a 'spare' wire with a connector on it. Is this the connector that should go to asnother terminal that doesn't seem to exist on thye current 'new' dimmer switch ?
I still don't undertstand why it wortked ok for a short while ???
The standard dimmer switch has 3 terminals on it. The one that you need has 4. Possibly it worked for a while until another part of the unit burned up putting you back in the dark. Here is what the correct dimmer switch looks like. Also, check your relay, because these have been known to burn out. The relay is located near the fuse block. Junk....
Keep in mind on that old of a car, I've seen melted connectors which will act up the same way. It will be very apparent when you go to remove the plug on the dimmer switch. Usually the source wire will over time produce enough heat to melt the connector. In that case replace the dimmer switch and repair the melted connector by cutting the wire out of it and replacing the connector end to fit snuggly.
These cars were notorious for melted connectors right from the start. The dimwit switch plug, blower motor relay socket, climate control head plug and power seat relay plugs were all high failure items. Aluminum spade terminals make heat while carrying high current.
I am here, but I am running out of suggestions. How long are the lights on before they go off? If you leave the headlamp knob pulled out, will the lights come back on? I am thinking of it being a bad circuit breaker, but that is a remote possibility. I am leaning toward the module being bad that is part of the Guidematic system. I will need to pull out the service manual and see what the book says. Only so much that the old brain can remember without going back to the books......JUnk.....
You either have a short in the headlamp system, or you have a defective circuit breaker. There are a couple of ways to check this. I will give you the easiest method. Turn off the high beams and see if the headlamps continue to work. If they do, then the problem is in the high beam circuit. If they don't, then unplug both low beam headlamps and turn on the high beams. If they stay on, then the problem is in the low beam circuit. If they go off, then there is a definite problem in the headlamp circuit. If that is the case, then I would consider a replacement headlamp switch, and also a replacement circuit breaker. Prior to replacing both of these items, I would find and unplug the Guidematic module. PM me your address and I will send you a diagram that might help...... Junk...
Ok I have replaced the dimmer switch with the correct 4 terminal version but headlights still fail to come on. Should I replace the relay ?
Is it the one on on the left under the fusebox, looking towrads the front of the car ? Has anyone a part no ?
I presume that the switch is ok but what about the circuit breaker ?
I forgot to mention that I have a Viper alarm/locking system fitted on my car and when I dropped the cover from under the steering wheel there was a lotta Viper stuff just hanging in there.
My car is a 76 CDV.
The 1977 Shop manual refers to a fuseable link between the starter and the headlamp switch. I would start there and see if it is burned out.... Junk....
A fuseable starter and the headlamp switch ? Jeez what is that supposed to do ? Could it be the relay ?
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