Hello all, first post here, have mercy on me!
I am troubleshooting my 76 convertible top, and I need to deal with the switch. Whats the procedure for removing the switch?
Thanks
First, disconnect the battery.
I removed the wood grain panel that the switch is fastened to.
There are 6 or 8 bolts behind holding it on.
Look at it from inside the glove box to see what you are dealing with.
If you have the three gang switch they come apart but you need to be careful doing this.
Good luck,
Brian
Switches are not the most common cause of no work tops. Most common issue is the relay. If it was run with a failing relay the motor often then fails.
Quote from: TJ Hopland on August 28, 2013, 11:04:24 PM
Switches are not the most common cause of no work tops. Most common issue is the relay. If it was run with a failing relay the motor often then fails.
Motor and relay both new. Multi-meter shows only 10v at relay so seems to not be getting full juice from switch. Top goes down fine but bogs down about a third of the way up.
A switch is all or nothing. If you are getting ten volts, then the switch is working as it is not like a dining room dimmer rheostat type switch. The likely reason for the voltage drop is high current drawn by the motor trying to overcome a bound linkage. If you require high power (a bound or sticky linkage) then the amps go up and the volts go down (they are a constant). Have you tried lubricating all the bearing points on the top mechanism, that certainly is easy and you have nothing to lose? The top mechanism is also a weak point on the convertible top operation. Another possible less likely cause is the alternator is weak.
The actuators on both sides usually need to be cleaned of their old dried grease and re-lubricated. Barry Norman
Do broken side tension cables affect the mechanism?
The side cables help the forward bow to choose the proper direction to flop as the top is coming up. This does not happen till the leading edge of the top is about over your head if you were seated in the driver seat so it won't effect the first 2/3 of the top movement. If the arms flop the wrong direction it will bind up real bad at the last part of the closing movement. Unless things are already badly damaged you won't even be able to latch it that way. When I have seen them like that the fix is to lower it slightly to take the pressure off then unbolt one of the bow arms and get it back the correct direction.
I just had my top done and had the shop do the side gear boxes. They said they were so stiff they were hard to get apart. I have not tried to operate the top yet since they said I should wait for the material to stretch so I don't know if its going to go easier now. Before it did slow down in a few spots if the engine was not running but it would still go up just on battery.
Did you just replace the motor or did you get a complete rebuilt / new motor and gear box? Was it from one of the big name top places or just some online place? If it was an old stock item you could have stiff grease in the 'new' box.
New motor, original gears, which are in good shape and well lubricated.
Also, with the drive cables unhooked, I can operate the top manually in both directions. If that helps.
The top motor circuit is not typical of the type of things you normally find in a car. Its also hard to find in the manuals. I took this from the power seat section in a body manual and quickly modified it to match the top circuit. The relay and motors are the same. Normally in a car or typical DC motor (like windows) you don't ground the body so you can just reverse the polarity to make the motor change directions. Not sure why they decided to make the tops and seats more complicated but they did, hopefully I can explain quickly here to aid in the troubleshooting.
In the diagram the relay terminals in the center are the ones on the short end of the relay. The outside ones are the ones that are down the center. The down the center ones can be reversed with each other and it will still work. The end ones can also be reversed and it will not make any difference in the operation.
The dash switch is nothing special either, its just a typical SPST (single pole single throw) momentary switch. There is a single main power feed to the switch and to the relay / motor so if one has power the other should too.
The motor grounds directly, no switching there. That leaves 3 wires. One is the line to the armature, this takes the full load so this is why its switched with a relay. The second part of the puzzle is the field. There is a up and down field winding. Only one gets energized at a time along with the armature through the relay. The signal from the switch powers both the relay that then powers the armature and feeds the field. If both don't happen all that happens is what does have power just sits and gets hot. What is kinda hard to figure out is where the relay coil gets grounded. The ground comes through the 'unused' field winding. This means with a bad motor or the motor not connected the relay will appear to not work.
Don't feel bad if you can't quite get this yet. I do a lot of electrical / electronic work and it took me some thinking to wrap my brain around this circuit. It does not help that there don't seem to be complete diagrams for the system in the manuals. It is on the full size diagram but its kinda hard to follow spread out over the whole car.
(https://forums.cadillaclasalle.club/proxy.php?request=http%3A%2F%2Fi148.photobucket.com%2Falbums%2Fs35%2F73eldo%2FCadillac%2FTopmotor.jpg&hash=128f82451081c3d108a0f616a132d33e21195b3f) (http://s148.photobucket.com/user/73eldo/media/Cadillac/Topmotor.jpg.html)
I also just noticed in that diagram on the ground side of the motor they show additional contacts, this is likely some sort of thermal circuit breaker. IF that was open the relay won't operate. Test for that would be to unhook the connector from the relay and connect ohm meter from ground to a field wire. You should get a fairly low ohm reading that way. If its high or open that thermal switch may be the problem.
I appreciate the great description, but I understand how the electrical bits work. I have read comments that the switches can get "tired" and not pass full voltage, thats what prompted my origibal post. The more research Im doing, though, I think my probkem is the two gear boxes that move the top. I am going to try to take them off and clean them up this wknd.
Thanks
Quote from: Tiger38118 on August 29, 2013, 10:21:14 AM
Do broken side tension cables affect the mechanism?
These cables are VERY critical to operation. If one (especially driver's side) or both are broken, the mid-span bow will not swing around correctly when the top is raised, and the entire thing will bog down and crap out. The cables not only make the tension correct at the sides when up, they also correctly manipulate the middle of the top frame.
I went thru this and the actuators were a large part but end of project it required a rebuild switch & a rebuilt up actuator and the side cable adjusted. What I picked up online was a "1971-1976 full size GM scissor top repair manual " (Ebay has some listed I bet)- it was worth the investment for me. You mention you have the original actuators, what I had to do was disconnect it from the top frame and move them manually. They have a lot of resistance but should move smoothly and not have any rough or binding spots. I found the bad one that way, but too an expert to help with the cable so the swing out was balanced. Almost seems they engineered the motor and parts where there is no extra push past a rough spot.
I have that book on the way.
Today's discovery: the side tension cables are indeed important as they ensure Bow 2 folds properly. After watching the mechanism a few times, I figured out the proper position for Bow 2 as it folds. If I manually guide that bow to the correct position on the way down, it comes back up fine. If left to flop around on its own, it binds the mechanism coming up.
I need new side cables.
TJ, your diagram and circuit description was very helpful in understanding the Relay. This rascal is unique and cannot be replaced or updated with any simple 12V-40 Amp Relay. There are TWO windings to actuate the Coil (Up/Down). Unloaded on the bench, my Motor draws 21 Amps, then within 30 seconds drops gradually to about 18 Amps. This is still a Lot of current (heat) for the Relay, which is fabricated with a plastic base (not bakelite). My Relay is partially melted at the armature terminal (red wire). This melted plastic had previously caused the internal Terminal of the Relay to tilt and not make contact when energized. So far I have not located an economical upgrade alternative to the $49-$79 "correct" Convertible Top Relay...but the search is on.
I'm not sure that a typical relay would not work. You would have to get the proper matching socket. You would have to make sure its not one with an internal diode across the coil. I think many of them are only 30 amps but they seem a lot more solid than the originals. It does seem like if it was that easy that more people would have figured it out by now, its not like these tops and seat motors are that rare. If mine ever craps out I will be trying alternatives before paying the big bucks for one that may soon fail again.
I don't know why GM used such odd relays. The heater blower relays seemed unnecessarily flimsy too.
I can hear the relay when I push the switch for up but, not when I push it for down. Wouldn't that mean it is the switch? Where can I get a new switch???
You have to remove the wooden appliqué that says Eldorado on the dash. There are 8mm head bolts from the rear and the nuts for the radio controls have to come off. The three way switch is in a bezel that also bolts to the appliqué. If you really think it's the switch you can disconnect it from the harness and test it.
The center pin is the hot and the ones on each side are up and down.
Actually if you remove the center dash section you can get to the harness without removing the appliqué.
There may be better ways to diagnose this but that's how you get at the switch.
I don't think you will find new ones but used ones pop up on eBay some times.