SCOTT's 90's

1990 Headlight Switch Repair Tutorial --

Recommended Posts

A few weeks ago I started having issues with my headlights; sometimes when I pushed the button they would not come on (the buckets wouldn't raise either). When I pushed the button again they would come on briefly and turn off, and when I pushed the button in slowly and with some slight force they would come on. So this went on for a while and eventually got worse until nothing worked ... I knew that it was the dreaded Headlamp switch possibly one of the contact bars had fell out of place or corrosion on the contacts.

Turned out being one of the bars had come loose and the other one was not making good contact.

 

Well today I finally decided to tear into the switch (this will be the fourth time over the years) and I thought that a tutorial or instructions on how to repair the switch might come in handy for someone wanting to repair their spare or broken one.

 

First off this is a very tedious job and requires a lot of patience :angry: but I will try to make it as simple as possible

 

Step 1.

Make sure that all three switches are turned ON ie: the ON push will have more resistance than the OFF and the ON will travel farther than the OFF. (I hope that makes sense) The reason being that each switch has its own lock position "ON" so that when you separate the housing parts won't fly everywhere.

 

Step 2.

1. Remove the Dimmer slider switch button.

2. Separate the two halves of the Switch housing by carefully prying up the sides to clear the tab locks and turn it on its side buttons facing out and SLOWLY remove the top with the buttons being careful not to depress the white buttons inside the housing and set the top aside. The top part has the buttons and they are just floating, and if you didn't have the switches pushed ON then this is where you will experience your first lesson in patience because literally everything will just fall out and look like a jigsaw puzzle, but no worries you can just skip the next step...:lol:

 

IMG_2615.thumb.JPG.a673ec62d6fa8153e87ecbc959b8c3b8.JPG

 

Step 3.

Inspect the internal parts looking for damage or loose parts and slowly start to remove everything.

1. First to get a feel for it start with the FOG light button (it's all by itself in the upper corner shown in above picture) by pressing down on it and slowly letting up and it will come out with a spring under it set it aside and repeat for the other two switches (they are combined so just remove both at the same time).

Take note at this time there are two contact bars one for the Parking switch and the other for the main Lights switch careful not to lose them; Also there are three small brass wheels for each switch keep an eye on them too.

IMG_2601.thumb.JPG.796599bcf2bb129a756baf4c101bbf54.JPG

 

IMG_2608.thumb.JPG.aee50b96b64425f7ac1dc6c3ba941ced.JPG

 

Step 4.

Once you have everything out and organized it is time to clean and re-lube the contacts.

IMG_2605.thumb.JPG.128c1b0db426db067160ccc937699cd2.JPG

 

"CAUTION" Be very careful cleaning the contacts on the CB (Circuit Board) if they get bent or misaligned in any way then you will have electrical problems with your switches. Each switch is activated by the height of the contacts 'Up & Down' for example on the main switch there are two contacts on the CB one of which is for the little indicator light which also shows "LIGHTS ON" on the IPC. I know this from past repairs and I had to tear apart the whole thing to carefully adjust that contact because it was sitting up too high making contact when the switch was OFF. I accidentally caught it with my towel and bent it.

1. Clean the Aluminum Bars and the contact points inside the housing, I used some 5000 grit paper to clean the corrosion (Arcing/Burnt) from mine.

 

IMG_2600.thumb.JPG.e9582b3e40dfa0265a8164f238defcdc.JPG

 

2. Gently wipe off each contact of the switches and remove any corrosion if necessary being careful not to bend anything.

3. Re-lube everything. I used some Electrical Compound and put it on all the contacts including the brass wheels and rocking points of the bars to help keep them in place for re-assembly.

IMG_2606.thumb.JPG.b2eab1bc032831191e00f8cb1f960a36.JPG

 

Step 5.

Re-Assembly - The FUN part:lol: (It helps if you have a small bench vise or something to hold the housing in an upright position because you will need both hands to do this).

 

1. Place the CB into the housing (Make sure to remove the clear plastic illumination piece it will make things a lot easier).

2. Start with the FOG light switch; Apply some Silicon or grease to one of the brass wheels and put it in place (The 3rd picture above is showing it in place)

3. Place the spring in the hole and put the white plastic switch on top of the spring and slowly push it down. Align the brass wheel to fit into the groove and once you push it all the way down let up on it and it will lock into place. You will hear a slight 'Click'

IMG_2609.thumb.JPG.ab57415420044b3787e90392aa119d36.JPG

 

I hope this video works if not sorry

IMG_2610.MOV

 

4. Repeat for the other switches (They are combined so you have to do both at the same time - this also requires patience just keep trying you will get it)

Place the two brass wheels into their spots as described above and then place the two rocker bars into their positions (This is where the silicon grease serves its purpose holding everything into place while you put the switches back in)

While you are pushing the two switches down you will also have to gently pull out on the sliding contacts over the two rocker bars

 

IMG_2607.thumb.JPG.95358c229329e94d0ee70911307ec6aa.JPG

 

 

5. Replace the Clear Plastic illumination piece CAREFUL not to bump or depress the switches.

 

IMG_2612.thumb.JPG.7c79e46bf71afdb853eba2d033a904e0.JPG

 

6. Place the Three spring bars into their positions making sure they are fully seated and in the correct direction.

 

IMG_2613.thumb.JPG.9b706633b207e46ad3d3254a68b50db2.JPG

IMG_2614.thumb.JPG.5fcbad96bbc52bb43a9299b8d4f87dcd.JPG

 

Step 6.

Re-Assemble the top part by laying both pieces on their sides with the buttons slightly tilted down and slowly put it back together - Make sure you do not press on the buttons until it is fully assembled or you will have a mess and will need to start over.

IMG_2616.thumb.JPG.fb86a17e84c86b0b72fd5b70b25ea244.JPG

 

You are all finished and all you have to do now is test it out to make sure all is working properly. If everything is working great then you can put the black knob on the slider dimmer switch.

 

I hope this helps someone if it does at least you won't have to buy a used one for $150 or more.

 

IMG_2611.JPG

Edited by SCOTT's 90's
Photo Placement (see edit history)
  • Like 3
  • Thanks 1

Share this post


Link to post
Share on other sites

Very good write-up. A couple of tips of my own to add based on rebuilds I've done:

 

Easy to determine if the switches  (lights, park, fog) are on or off by partially depressing each switch face (prior to disassembly,  but not enough to change the state of each switch) to see if they will move inward about 3/16". If they do, that switch position is already on, if there is no inward movement the switch is off and needs to be pressed to turn it on before disassembly.


Second, be very careful not to bend or misalign the fixed contacts/pivot points where the two rocker contacts sit. These are molded into the plastic housing and if bent or distorted, will cause the lights and/or park switch not to toggle properly as the white actuator plungers will get hung up. They are very difficult to straightan if they do get messed up.

 

Third, I heavily recommend taking a proper size piece of heatshrink tubing and putting it over the clip that holds the base of the stem extender to the dimmer slider (and use an appropriate heat source to shrink it over the clip) as this plastic clip breaks easily. Doing so will help clamp the clip in place better and preclude the extension from breaking free (if it hasn't already). Note this also applies to the twilight slider on 91 switches.

 

Finally, I suggest applying some sort of sticker or tape with strong adhesive to overlap where the front enclosure overlaps the rear of the switch housing. This will help avoid the dreaded switch "explosion" that is known to happen periodically with these  switches as the snap together housing tends to get slightly weakened with disassembly which makes the blow apart more likely. Anyone who has had this happen knows it is terribly frustrating as small parts from inside the switch tend to get lost in the process.

 

 

 

 

Edited by KDirk (see edit history)
  • Like 2
  • Thanks 1

Share this post


Link to post
Share on other sites
6 minutes ago, KDirk said:

Very good write-up. A couple of tips of my own to add based on rebuilds I've done:

 

Easy to determine if the switches  (lights, park, fog) are on or off by partially depressing each switch face (prior to disassembly,  but not enough to change the state of each switch) to see if they will move inward about 3/16". If they do, that switch position is already on, if there is no inward movement the switch is off and needs to be pressed to turn it on before disassembly.


Second, be very careful not to bend or misalign the fixed contacts/pivot points where the two rocker contacts sit. These are molded into the plastic housing and if bent or distorted, will cause the lights and/or park switch not to toggle properly as the white actuator plungers will get hung up. They are very difficult to straightan if they do get messed up.

 

Third, I heavily recommend taking a proper size piece of heatshrink tubing and putting it over the clip that holds the base of the stem extender to the dimmer slider (and use an appropriate heat source to shrink it over the clip) as this plastic clip breaks easily. Doing so will help clamp the clip in place better and preclude the extension from breaking free (if it hasn't already). Note this also applies to the twilight slider on 91 switches.

 

Finally, I suggest applying some sort of sticker or tape with strong adhesive to overlap where the front enclosure overlaps the rear of the switch housing. This will help avoid the dreaded switch "explosion" that is known to happen periodically with these  switches as the snap together housing tends to get slightly weakened with disassembly which makes the blow apart more likely. Anyone who has had this happen knows it is terribly frustrating as small parts from inside the switch tend to get lost in the process.

 

Thank You very much for those pointers it will help a lot!

  • Like 1

Share this post


Link to post
Share on other sites

Scott,

Thanks for taking the time to post your tutorial on rebuilding the headlight switches. I'm sure you spent a lot of time on it.

  • Like 1

Share this post


Link to post
Share on other sites

FWIW, if anyone reading here gets into a jam and needs a switch reassembled because they aren't comfortable doing it themselves,  drop me a line, and I'll do what I can to help. Keep in mind, I have a very limited supply of spare parts for these switches on hand, so if your switch blew apart and there are pieces missing,  I may or may not be able to make a complete switch from it. I do have plenty of extra 1991 switches,  but no 1990 versions. 

 

 

Edited by KDirk (see edit history)
  • Thanks 1

Share this post


Link to post
Share on other sites

Ok- could someone definitely say, how much of this pertains to '88-'89 headlight switches? Details of differences, please?

 

Also- whenever I've had to disassemble something that was spring-loaded, and/or had small parts- I always found it helpful to either take it apart inside a plastic shopping bag, or wrap a towel around it to contain the granade:D

  • Thanks 2

Share this post


Link to post
Share on other sites

88/89 is a completely different switch internally, and more mechanically complicated. The common issues are the lights off button not latching reliably (due to either internal wear or heat damage to the mechanism) and melting of the rear housing and internal terminal strip insulator due to excessive load or high circuit resistance. Another fairly common problem now is the EL backlighting failing from age, and there is no really good solution for that so far short of finding a good donor switch.

 

My biggest warning regarding these switches is never to try to spray contact cleaner (or worse still wd-40) into the switch as this will ruin the plastics and do no good anyway since the design of the switch buttons and enclosure pretty well guarantees no spray cleaner can get inside without disassembly. Usually there is no issue to be solved by contact cleaner anyway, almost all failures are of a mechanical nature, not dirty contacts.

 

When the switch melts from overheating, it typically warps the rear enclosure around the terminals. This also damages the internal guides that align the brass slide bars (smooth operation of these is critical to the lights/park/off switches interacting and latching positively). Once this happens the switch is junk  (goodnforna parts donor only) as there is really no way to correct the distortion in the molded plastic and get everything to move straight and smooth again. It will also tend to create a condition where the switch will heat up again and melt even worse, leading to damage of the vehicle side harness in the dash whuch then needs to be repaired or replaced.

 

There aren't quite as many small parts that can easily get loose inside the 88/89 switch, but there are some and one needs to be careful not to loose them when disassembling. Particularly the actuators for the cruise and hazard switches, and the small auxiliary slide contact held captive under the one brass slide board on the rear of the PCB. Also need to be very cautious not to break the stem off the dimmer slider when reassembling. The slot for this slide in the front housing is very narrow and if the slider is misaligned just slightly, it'll break off when snapping the front and back housings together.

 

The plastic bag containment method is good advice generally, but still leaves you with a lot of small parts you have to figure out how to reassemble, which isn't always readily apparent. 

 

Edited by KDirk (see edit history)
  • Thanks 1

Share this post


Link to post
Share on other sites
27 minutes ago, KDirk said:

My biggest warning regarding these switches is never to try to spray contact cleaner (or worse still wd-40) into the switch as this will ruin the plastics and do no good anyway since the design of the switch buttons and enclosure pretty well guarantees no spray cleaner can get inside without disassembly. Usually there is no issue to be solved by contact cleaner anyway, almost all failures are of a mechanical nature, not dirty contacts.

 

I have no doubt that you are right. Back when I first got my Reatta the switch would stick and I would have to push the buttons on and off several times to get the switch to turn the lights off. On the recommendations of another forum member, I flattened the spray tube and sprayed WD-40 between all the cracks around the buttons and let it sit overnight with the battery disconnected. It has worked great ever since. I guess I just got lucky. I use to recommend people do this but I no longer do. I believe it was Dave that ran into problems when he did it.

Share this post


Link to post
Share on other sites

Ronnie, the problem with WD-40 specifically is that it gets gummy as it evaporates and attracts dirt and dust making things worse in the long run. Because the switch is right next to the dash vent, it will pick up a lot of dust.

 

Most proper contact cleaners are harmful to plastic, and especially the button faces which are screen printed in two layers, white and then a black overmask to create the button legend. I see many switches with deteriorated button legends or other damage (discoloration or melting of plastic) due to use of contact cleaning solvents. 

 

The second issue with doing this is that the switch is designed in such a way that there is a "skirt" around each switch button (not visible from the outside, it is behind the openings in the front housing) so spraying anything in around the button faces will not normally make it to the contacts, but will just disperse around the margin of the switch button. This may help a little if the button faces are sticking where they slide in the molded channels inside the front housing, but will do nothing for the electrical or mechanical portions of the swtich as it will never make it in that far.

 

The only real opening in the switch face is the slot for the dimmer slider, and that doesn't allow you to aim anything into the upper portion of the switch. Another issue is that solvents will damage the EL strip as it is laminated in thin plastic, and by this age usually has cracks in the lamination. This allows solvent to get directly on the EL substrate and ruin it, killing the backlighting. 

 

I've been lucky to have some success refurbing these switches, but they are complicated and there are some internal plastic parts that wear enough that they have to be replaced with pieces from a donor or it will never be reliable again. Ditto with the melt issue, I've yet to get a switch that overheated and melted to ever work 100% right again no matter what I do.

 

And as already stated, the backlighting issue is getting to be a big problem for those of us who want it working. Good EL  (meaning bright and consistent) is ever harder to find on a used switch now; there is no good DIY way to fabricate a new piece of EL for replacement,  and I've tried. I have found an outfit that will custom fabricate an EL sheet from a CAD drawing, but the cost involved and minimum orders make that impractical given present demand.

 

 

Edited by KDirk (see edit history)
  • Thanks 1

Share this post


Link to post
Share on other sites

Thanks Kevin. I always enjoy your well thought out posts. As I said, I must have got lucky that I didn't damage anything and it corrected the problem. There must have been something sticking that the WD-40 either blew out or lubricated. I've never had one of the switches apart so I don't know.

Share this post


Link to post
Share on other sites
2 hours ago, KDirk said:

Ronnie, the problem with WD-40 specifically is that it gets gummy as it evaporates and attracts dirt and dust making things worse in the long run. Because the switch is right next to the dash vent, it will pick up a lot of dust.

 

Most proper contact cleaners are harmful to plastic, and especially the button faces which are screen printed in two layers, white and then a black overmask to create the button legend. I see many switches with deteriorated button legends or other damage (discoloration or melting of plastic) due to use of contact cleaning solvents.

 

Thanks Kevin, that is why I didn't use any of those cleaners since I have had bad results with them in years past.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now