Conv Switch

Discussion in 'The ragtop shop' started by bmcmillan, Aug 2, 2002.

  1. bmcmillan

    bmcmillan Dented Hood Tach

    I have a 1972 GS Convertible.
    I have been experiencing problems with my top switch.
    I just put in a different switch in about a month ago.
    The switch looses its spring back to center, and then the
    switch doesn't work any more. This is my third switch.
    I must be overlooking something.
    Has anybody by-passed the original switch, and ran
    something under dash?
    Sure would like to drop the top!
  2. Marco

    Marco Well-Known Member

    Hello Stranger, and welcome to the V8Buick board!

    We're all pretty friendly 'round these parts and we would appreciate if you sign your posts with at least a first name so we know who we're 'chatting' with.

    I've never heard of the top switch spring doing that that quickly. It doesn't take much pressure to work the switch. Keep it gentle and the switch should last fine. Maybe the second switch was on it's way out? If you lightly press the switch, you should be fine!

    I should know - my wife was 'helping' me bleed the hydraulic system by working the top switch while I was filling the reservoir. Well, she apparently thought she was going for an Olympic record and basically put so much pressure on the switch she ruined it. :Dou:
  3. bmcmillan

    bmcmillan Dented Hood Tach

    Sorry about not having a Signature.

    The switch just lost power on the DN side,
    Then lost power on the UP side
    Could I have a ground problem at the motor?
    The switch before like melted, on opposite side of the
    three prong.
    I have notice that the top switch gets really
    warm when I use it.
    Jim Weisse helped me put this last switch in.
    The switch we put in, seemed like a good switch.

    Brian McMillan
    72 Buick GS Conv 455
    BPG #1077
  4. Marco

    Marco Well-Known Member

    Hi Brian -

    Do you have a chassis manual/Fisher body manual?

    The switch does get hot, but you definitely need to check your wiring if you think it's getting so hot it's ruining the switch. That's not good - I'd hate to hear you had an interior fire.

    You can easily check the ground in your trunk since I believe it's in plain sight, but I think there is also a ground in one of the (3) wires going to the back of the switch.

    Your best bet is to look at a wiring diagram. If you can't find one, I can look in my manuals and see if I can find this info. Sorry, but I probably wouldn't be able to get you this information until al least next week.

    Let me know if you need any help.
  5. NvrDun

    NvrDun Founders Club Member

    Hi Guys,

    I have been looking for a convt switch for a while and have not found one. I have most of the parts manuals Y1, OPGI, Poston and CARS and I have not seen it.

    Any help locating one would be very appreaciated.

  6. Marco

    Marco Well-Known Member

    Rich -

    When I needed one, I put a 'Parts Wanted' post on this site and the BCA website.

    You'll definitely find one this way!

    PS - get a spare if you can...
  7. Jim Weise

    Jim Weise 1000+HP


    Oh sure, I give you a perfectly working switch, and ya' fry it..:laugh:

    Seriously, since you have a history of this problem, I would suggest that you may have an issue with the motor, or the top mechanism itself may be binding, causing the hydraulics to overload, and working the motor harder. We need to remember that a DC motor draws more amperage the slower it runs, so if excessive Hydraulic pressures are required, the motor may slow down, drawing more current than normal, and frying the switch.

    Until you track down the problem, make sure that next time you wire a 30 amp relay into the circuit.. that way, you use the hard to find top switch to do nothing but activate the relay, and if the problem perisists, then the worst thing you have to replace is and easy to find $6.00 relay.

    I never did see the top go up and down, I guess I should have had you run it thru a couple of cycles while you were here, but we were frying bigger fish at the time.

    When I am out and about, I will look for another switch for you, and can send you a pre-wired relay assembly ... and for the rest of you ragtop guys, it is not a bad idea to have something like this, as the switch on the dash is carrying full motor current, and will eventually wear out. I know when I put my ragtop back together, I will definately not run all that current repeatedly thru a 33 year old switch... running just a fraction of that current thru the old switch will extend it's lifespan dramatically.

    'Ya know, while I am thinking about it....

    If you guys are interested in a kit for this, let me know, as I have a stage ragtop that will be in the shop in a month or so (ya Cole, that's you!) and I can put together a kit, should be an inexpensive one, that will be easy to install. I will design it so that you don't have to cut the harnesses up, but just add another harness in, and then indiviually wire the switch terminals.. should be no biggie to install, worst thing will be getting behind the dash to get at the switch connections, which is no biggie, if you pull the pad, and access it from the hole above the radio. AC guys will have to take out a couple of screws, and remove the center vent duct. Prolly gonna cost about $25.00, for a nice 30 A relay setup, with a molded plug for the relay, and all the wiring and connnectors required. Pretty cheap considering the trouble and cost of finding a switch.


  8. Brian,

    Great to see you on the board! If you're interested in having one of the pics I took of your 'vert re-sized to use as an avatar(pic), let me know, and I'll get it emailed over to you. Or maybe I can upload it from here, then I think all you need to do is browse the available avatars from the "user cp" choices.
  9. John W

    John W Member

    Conv. top switch relay

    I sure would like to get one if you decide to make them. Let me know when and I will send the cash.
  10. NvrDun

    NvrDun Founders Club Member


    I did not know the switch handled all the juice, so what you are planning is making the switch more of a basic switch and have the power handled by the relay behind the switch, if that will extend the life of the switches that would be excellent.

    I would be interested in this for atleast 2 maybe 3.

  11. bmcmillan

    bmcmillan Dented Hood Tach

    Thank you, I do have all the manuals.

    I will buy the conversion kit. I will try to find out what the
    problem with the switch is this week. Maybe it is something else.
    I noticed that I lost power first on the UP side, then it quit
    working on the DN side. It seems to still have the self center
    on it. Not like the last one I had. I need to get that working

    Yes, please send some pictures of my car.
    If you could, make them a little smaller.
    I am using the car show one as a screen saving here at work.
    I like it.

    Brian McMillan
    72 GS Conv 455
    BPG #1077
  12. Marco

    Marco Well-Known Member

    Re: Hey...

    Hey Jim -

    Good idea! I'll talk to you at Duane's house about it. I'd like to get a little more info, in addition to what I would need to take apart.


    PS - Is Cole's GS a factory Stage1??? (Cole, you out there???)
  13. Jim Weise

    Jim Weise 1000+HP

    Nope, Cole's is a GS455, but I do have a 72 STG 1 Convert here in the shop, not sure about documentation on this one, but it does have the correct engine code in the VIN.

    I will relay your info on the STG 1 Registry to it's owner.

    Too many ragtops around here... to keep them all straight..:Dou:

    I will get to work on a kit shortly, I have that Stage car here for a complete driver resto, so it is all together now, so I can build the kit, and then write the directions based on doing it with a completed car.

    Yes, the kit will use the factory switch to simply activate the the electronic relay, so the current flowing thru your 30+ year old switch will be just a fraction of what it is handling now.

    I will get back to you all on this in a couple of weeks, after I put together the kit, and install it on one of the ragtops in the shop here.

    As always, I will be doing daily testing of the system, to prove it's function and dependablity, before I offer them for sale, and the kit will include very complete instructions, and the relay will be wired up, all you will have to do is make the wiring connections that are required in the car. I am going to try and make it, so all you have to do is pull off the dash pad, and possibly remove the center AC Vent ductwork, if so equipt. It will be a bummer if you have to pull the dash cluster... that is not fun.
    But I don't think that will be required.

    Off to the drawing board.....

  14. Marco

    Marco Well-Known Member

    1972 VINs are good enough for me :cool:

    Thanks for the info relay Jim, and God willing I'll see you in two weeks!
  15. TimR

    TimR Nutcase at large

    Just some info here, as useless as it may be. If you have a top switch that is physically broken (attach point, etc), you may be interested to know the case and the the switch knob itself are the same on the rear defrost switch. Only the little plate inside with the current transferring mechanism is differerent..and that only amunts to different pin arrangement and the little tabs bent further out so the top switch will return to center when released.

    Thought it might help someone out. Also, I think JW's idea is a very good one, I find it hard to beleive they actually ran all that current through that little switch (pry the clips off the side and look at the contacts....30 amps???LOL).

  16. pakual

    pakual San Jose California

    Hello all:
    Another idea, The wiring runs close to the steering column. My switch did the same thing because I lowered my column and when raising it back in to position I pinched the wires. As Jim said there is a lot of juice and the wires cannot be crimped.
    Freeing the wires up was all it took. I originally thought the motor or switch was bad.
    I think the rear window switch in a Station Wagon is the same as the top switch. Another place to look.
    Good luck
    JA :)
  17. bmcmillan

    bmcmillan Dented Hood Tach

    I went back and tested the conv switch. I do have power at the
    middle prong. When I try the DN or UP side of the switch, No
    power. The switch has failed.
    I know JW is working on a relay for the Conv Switch.
    So I was wondering if you mounted a relay back by the conv
    motor to take up the amperage from the switch.
    thinking that you would not be running the amps all the way
    up to the back switch. The juice would still be minimal at the switch and through the wires from the relay.
    Would that work JW.
  18. Truzi

    Truzi Perpetual Student

    I really like the relay example, and your idea of the relay at the motor should work. If Jim's kit puts a relay at the switch, it makes installation easier.

    However, if your car fried the switches so quickly, I'd still check out the wiring to make sure something isn't wrong before putting in a relay.
  19. r72gs

    r72gs Another project........

    Check the ground

    The ground goes from the pump/motor to the brace that the rear seat back attaches to, may be that simple and it's easy to check. The relay is a great idea, I'm going to add one to mine before I get the dash back in.
  20. TimR

    TimR Nutcase at large

    I've already been looking at the relay idea as well....I think it would be best to mount it near the fusebox for easy access....couple of old harness GM wiring connectors and can plug the whole thing into the stock wiring harness, no cutting needed.

    Problem with putting the relay setup at the back is you will still need to run power from the front (unless your battery is mounted in the trunk) capable of operating the pump and without excessive line loss, AND the control wires to control the system(relay), so it just adds wire. The stock switch harness plugs into the middle harness right by the fusebox, so you can access the power needed easily, less wire to run as well.

    The pump motor is a reversible motor so you can't just interupt the ground side, it has to be directional (which is too bad, it wuld really make things easy).

    The contacts inside the top switch and the defrost switch are the same as well (I've been playing), just the two prongs in the middle for the return (or not) are different, and adjusted just by bending them (thats how GM did it) if your contacts inside the switch are pitted, you can use the element from a defrost switch which didn't carry much current, usually very nice shape (whereas the contacts in my top switch element were burned right up). It compounds itself since the pitting causes more resistance which in turn causes heat buildup and more pitting and the cycle continues....


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