Chrysler 300M Enthusiasts Club
  • [How-to] Repair (and not replace) a brake light switch

  • LH Performance Modification Discussions
Ocean City 2019 Banner

Membership Banner

LH Performance Modification Discussions
User avatar
 #346866  by remi
 June 26th, 2015, 10:36 am
Hi there!

A while ago I posted a how-to on DodgeIntrepid.Net but I found out "how-toes" are not easy to find or advertised on DI.Net... So I thought I should post it here too.
Admins, feel free to move this subject if it's in the wrong section (KB maybe?).

Ok so you don't like throwing money out of the window, and you like to repair stuff instead of replacing with new parts, or used parts you never know when they fail like your old part did...
And guess what, you got pulled over on your way back from work because of your brake lights not coming on when stoping at a red light with a police car riiiiiiight behind you!

Of course, you have already checked all your fuses AND light bulbs, everything is fine. So next step is to remove the brake light switch, located on your brake pedal mechanism. I won't talk about this, this step is well described in the repair manual.

1st step : is this brake light switch working or not?

First thing you can do is shaking the switch and listening to debris... In my case I could definitely hear some metal moving inside!
When holding the switch with the black lever pointing to the left, you should see 6 metal connectors... We'll number them #1 on left side to #6 on right side.

Contacts when the switch is at rest should be:
- 1 and 2 closed (connected)
- 3 and 4 open (disconnected)
- 5 and 6 open (disconnected)

Contacts when the switch is "pushed" (applying pressure on the lever) should be the opposite:
- 1 and 2 open (disconnected)
- 3 and 4 closed (connected)
- 5 and 6 closed (connected)

Use an ohmmeter, multimeter or whatever you have to check for connections... I forgot my multimeter at my dad's place last time I visited him so I built a "tester" using a light bulb and a computer power supply. Be creative ;)
(Yes there are wine caps on my table, yes I drink wine - my father is a wine maker, that explains a lot - and no I didn't drink 2 bottles, I use caps to keep small screws organized untill I flip the caps... oh well)

And that is how I checked for continuity between connectors. Move from left to right to check continuity (see above for reference values).

And because videos are easier to understand than text, there you go:

2nd step : crack that switch open !

There are four retaining clips that need to come off. The small one (on the connector side) is super easy with a small screwdriver. The other ones were a PITA so I simply break them all off. If repair is successful you can glue the two parts together using epoxy!

Oh look at this... The left tab (actually on the right side on this picture, I fliped-flaped the cap on this one) making contact (or not) between the connectors #1 and #2 (dedicated to the brake lights) is broken!
Now, use a soldering iron and tin both parts, keeping the extremities (left and right here) clear like in this picture. Of course you need to do it on both sides (up and down).

You may solder the two pieces together without any other support but tin is very flexible so I doubt this would work for long.
If you want to add more strength to the tab, to make it more durable, take some brass fasteners and cut the legs off.
Tin one side ONLY of each leg, and trim the legs to a good length. Check twice before cutting.

Use two more brass fasteners to hold the tined straps from the previous step to the two tab pieces. Make the tined sides of the tabs and the strap facing each others.
Using a soldering iron, apply heat ONLY onto the strap. Heat will travel along the tined surfaces, soldering the strap to the tab pieces.
Do it on both sides (not represented on this picture) so you have two straps on one surface of the tab. Keep the fasteners in place while soldering the other strap, so the first one is still secured when the tin melt.

It's difficult to see on this picture but I added two more straps on the back. The tab is now secured with FOUR straps, drown in tin.

I didn't take a picture but... You may want to check for corrosion on all tabs and pads (the round parts on the hard metal pieces making contact with the flexible copper tabs).
After a few soldering jobs (I had to solder a few times to achieve better results) the pad on #1 wasn't conducting electricity anymore, I guess some rosin residues from the tin (on the facing tab, the one I repaired) settled on the pads.
And BTW, after a few years of service, the pad was "eaten", there was a small hole in it. So I used a thin sand paper to clean the pad, and applied some tin on it with my soldering iron.

Mount the tab back onto the plastic cap. The cap is used as a bracket for all tabs and connectors.
Check for proper alignment, and be sure the copper tab you soldered is free to move like the other ones.

Take the other part of the switch in your hand like in this picture, with the switch lever on the left.
Apply some pressure to the lever to make the switch core sliding. See the two plasting marks (or tabs) on the core, in the left window? That's where the left metal tab on the previous pictures need to go!
Put the two parts together while keeping constant pressure on the lever to keep it at the desired position. Check for alignment with the tabs... Check twice!!!

Test your repaired switch (again, see above for reference conductivity values) and if everything is working as expected, seal the parts with epoxy.
I disassembled the switch again for this step... I put some epoxy where the plastic retaining tabs used to be, checked for alignment again, reassembled everything, tested the switch, and set aside for the glue to dry.

One more video:

Please note that this how to may not be the best solution. Of course if you have a brand new switch, use it... However if you are in a hurry, like you need the car asap and you know you won't get a new part soon enough, this how to may be the way to go.

By the way this switch was (is?) used in many Chrysler/Dodge/Jeep vehicules:
- LH platforms, 1st and 2nd generations, Vision, LHS, Concorde, New Yorker, 300M, Intrepid
- LX cars (Charger, 300, Magnum)
- Neon
- Stratus, Sebring, Cirrus (1st and 2nd generations)
- Voyager and Grand Voyager
- Jeep Wrangler, Cherokee and Grand Cherokee
- Prowler
- Viper
- RAM 1500, 2500, 3500, etc...
Of course, check for years as there might be different parts.

Feel free to comment, I'm always eager to learn more