I had to rebuild the hydro-boost on my rig for a leaking seal. Found a YouTube page with very good instructions for the repair. They did recommend replacing the brake light switch also as it was a one time use only item. If you didn't replace it your brake lights would stay on all the time. Seems like it loses it's setting once the brake peddle is disengaged. Got a new switch and the install was fairly simple.

Took the old unit apart to see if I could "reset" it. I was expecting a small circuit board of some kind but it was totally mechanical. Not sure I'm seeing what could be out of whack just by removing and replacing the switch on to the same peddle & rig. It's just a plunger with several ears (cams) engaging and disengaging a few micro-switches.

Anyone know for sure if you can reuse these or not?

 

 

If it still functions properly I would not worry about it. I re sealed my booster 3 years ago and still have the switch I bought back then. I do not remeber what I did to not replace it however.

I already have the new switch installed. I was getting ready to toss the old one but decided to have a look inside. The thing actually looks brand new inside and out.

Anyway, all info online says the switch is a one time use item. I got 20 years and 200K miles out of it so no complaints.  I just don't see anything that could become misaligned simply by taking it off and then back on.

I've always wondered about that as well. The "DO NOT REINSTALL" warning is molded into the entire side of the switch, but I've never understood (or explored) what would prevent it from working just fine if reinstalled. Always figured it was just a liability thing.

 

I also have no memory of whether I replaced or reused after replacing my booster 10 years ago. But my brake lights work fine.

Edited August 9, 20213 yr by sleezy

So there's the inside of the unit. The only thing I can see that might get locked into place is the broad chrome band on the far inside/right part of the housing. But even if that's it, it should still work on the original setup. I can't see how taking it off and right back on would throw it out of adjustment.

If I was a gambling man I would take out the new one and try the old to see if it still works. Problem with that is if they really are "one time use" I would have to go buy another for ~$20 bucks. 

About 150,000 miles ago my brake lights were staying on.  I removed the brake light switch and modified it to be reusable.  I cannot remember what I did to it, but I know it was simple.  I am currently using the original switch now with over 350,000 miles on it.

 

- John

It probably is something to do with that metal band. Like if you put it on a truck where the pedal sits a little lower then the brake lights stay on because it's been "calibrated" for a taller pedal (similar to what Tractorman experienced). Obviously they can't recommend taking a component apart, especially on a safety device. That big warning makes sure that it's not their fault if you mess with it and it stops working.

Found this warning from Genos Garage:

"IMPORTANT NOTE: You must read the instructions before opening box. Do not press in the switch plunger before installation as it will damage the self-adjustment mechanism and render the part unusable. The warranty will be void if this happens"

It could be a liability thing! I might just have to put the old switch back on (damn the $20 bucks) and see what happens. 

32 minutes ago, MikeH said:

"IMPORTANT NOTE: You must read the instructions before opening box. Do not press in the switch plunger before installation as it will damage the self-adjustment mechanism and render the part unusable.

 

10 hours ago, sleezy said:

The "DO NOT REINSTALL" warning is molded into the entire side of the switch

 

It is beyond my ability to comprehend as to why a simple brake light switch would be engineered in such a manner that it could not be reused.  i suppose if you removed your brake pedal, you couldn't use that again either.

 

- John

If you look at the design it has a ratchet design to self adjust during install. If you carefully pull the plunger back out you can re-install it again. Yes I've actually figure it out and been able to re-install two switch before. 

I think every brake light switch is "not reusable". I had to do one on one of my vehicles and it didn't have the lever like the Cummins. When you let the brake lever contact the plunger and start to push it in, you could hear either something slide or ratchet slightly until the end of the stroke of the pedal, then it was set.

 

I think that its for either multi vehicle compatibility or its for dealing with tolerancing of everything from the hydrobooster to the dash. 

 

@MikeH, what does the lever on the end that you flip after install actuate? Is it the position lock for that metal collar?

 

From the photo, as best as I can tell, the plunger is telescoping. It slides into the part with the cams, bumps, etc that hit the switches. The spring is for returning to extended position, and I think the metal collar is what grabs the plunger to move the assembly (plunger and cams) when the pedal is released.

 

From the look of it, there could be an issue of age with that lever that looks to clamp the metal collar. The rod its attached to is supplying tension to keep everything working but after a long time of the collar sliding on the rod, it might not be able to keep enough tension on the collar and then the spring force overcomes the tension provided. That causes the cams to push forward and you to have brake lights on all the time.             

8 hours ago, Silverwolf2691 said:

 

@MikeH, what does the lever on the end that you flip after install actuate? Is it the position lock for that metal collar?

The plunger itself is two parts. Think of a 1" plastic pipe sliding into a 2" plastic pipe. As I see it the black lever on the end holds the chrome collar open to allow the two pieces to slide freely. The internal part of the plunger (that 1" pipe) has grooves or teeth. This is that ratcheting action described by MoparMan. Once the unit is installed you throw that black lever and the collar clamps down locking the outer to inner parts of the plunger. This sets the "open circuit" (i.e. no brake light) length of the plunger. Now when you hit the brake peddle the whole plunger moves hitting one of the micro-switches which turns the brake light on. 

I still see no reason why my old switch wouldn't work. I guess it's possible the rebuild on the hydro-boost could throw things off a little but... I think I'll just keep the old switch in the glove box.

Thinking it over a little more I believe I see the reason for the "Do not reuse" warning. There's two big reasons you pulled the switch off in the first place:

A. The switch internals broke or became gummed up somehow. Switch is totally inop and needs replaced.

B. You pulled your brake peddle off to replace the hydro-boost or master cylinder

Either one of those could cause the brake light to either not come on at all or stay on all the time. Big safety issue so there's a warning to replace it anytime it's removed.

I think my switch was fine as I only rebuilt the hydro-boost so the brake rod and throw of the peddle would stay the same. Once I saw what was going on inside, and the tip from  Mopar1973Man, I pry open the locking collar and extended the plunger somewhat. It should reset to the correct length if I ever install it again. Mystery solved.

BTW, I found it easier to pull the whole bracket (two bolts) when removing that switch. With the bolts out the bracket, switch & elec connector are hanging down below the dash and real easy to work on.  

The only problem is the ratchet design won't allow for multiple resets eventually the ratchet will fail. 

10 hours ago, Mopar1973Man said:

The only problem is the ratchet design won't allow for multiple resets eventually the ratchet will fail

Right...they're barely scratches in the plastic plunger. Of course what you do then is to break out the JB Weld!

Just looked it up on RockAuto.Com a brake light switch is a mere $7 dollars!!! Really you going to go that far to save a 7 dollar brake light switch... 

 

https://www.rockauto.com/en/catalog/dodge,2001,ram+2500+pickup,5.9l+l6+diesel+turbocharged,1366602,electrical-switch+&+relay,brake+light+switch,10474

1 minute ago, Mopar1973Man said:

Just looked it up on RockAuto.Com a brake light switch is a mere $7 dollars!!! Really you going to go that far to save a 7 dollar brake light switch... 

 

HEY...I got ripped off at Auto Zone! They charged me $20 bucks!

Just now, MikeH said:

HEY...I got ripped off at Auto Zone! They charged me $20 bucks!

 

Should follow me more. I've been getting good quality parts for year but paying less. I just checked NAPA (Prolink) its $21.79 my cost but list or the public for $31.70. Then I fall back to RockAuto.Com and typically find good deals but the waiting for mail is the slow part. 

When I buy stuff from Advance if I order it on line and pick,it up I usually get for 20 to 25% off. Walk in the store and buy it, it's full retail. 

It's all good guys. My OE switch is now in the glove box for a spare. The new over priced switch is the first replacement in 20 years. Let me do the math...$20 dollar switch over 20 years...ummm...yep...a buck a year. 

The brake switch story was actually a side note here. The big thing was getting the hydro-boost off, resealed & back on. It went without a hitch. I couldn't see a darn thing wrong with the main seal and the internals looked very clean with no rust etc. But, the new seal was the fix and we're ready for the next big road trip. Can't wait to get "The Big Dog" back on the road.

ps: spruced up the engine bay while I was down

4 hours ago, MikeH said:

The big thing was getting the hydro-boost off, resealed & back on.

I'll make you think a second I've never had to rebuild my own hydrobooster yet. 432k miles and still going. The biggest thing is keeping the power steering fluid changed every 30k miles. If you keep up on the fluid changes then you'll never have to rebuild the hydrobooster.