If the armature in your convertible top motor never wears out, your top switch shouldn’t wear out either. Roll back the clock to grade school science class. Remember the electromagnet you made, and how you’d put something like a paper clip in between the two nails and watch it move? That is the same concept behind an electric motor. The armature is the paper clip. When it wears out, it opens a circuit to ground. This makes the motor draw a lot more amps than it normally would. More amps equals more heat. This heat is what damages the top switch. At least in my case.
The 1970 service manual is great at guiding the reader through most repairs. It fails on the top switch. The service manual tells you to remove the instrument panel trim and clusters. Then you just reach behind the dash, remove two screws holding the switch in place, and you are done. Sounds simple? Not so fast. Your car may differ, but on my 1970 Cutlass Supreme convertible there is a support post right behind the switch. It blocks one of the screws, making it impossible to get any kind of tool on it. You know what that means?
See that vertical brace just behind the steering wheel? Guess what sits right in front of it?.
Yep, you have to remove the dash to do the work. Happy day!
Truth be told, you really don’t need to remove the dash. In my case, the dash came out because I also need to replace the heater core. If you only need to replace the convertible top switch, loosening the dash will suffice. It’s still a lot of work, but a convertible without a working top switch is a bad idea if you live in Seattle. This procedure will work on any 1970-72 Cutlass Supreme convertible. They all used the same dashboard.
Tools Needed:
- Refer to the dashboard removal guide
- A 1/4″ combo wrench
To remove the switch:
Referring to my dash removal guide, do everything in Part I.
The goal is to loosen the dash so you can get at the one pesky screw that is blocked. As long as you remembered to disconnect the battery, you can leave all the wiring and vacuum hoses hooked up. The wires and hoses have enough slack for you to move the dashboard the inch or so required to access the blocked screw. For Part II of the dash removal, skip Step 1. For Step 2, remove only the convertible top switch wiring connector; it’s got 4 wires. Skip Step 3 and 4. You will need to do Step 5, 6, and 7. You are now ready to remove the switch.
1) Move the dashboard just enough to gain access to the blocked screw. You should only need to move the dash up a bit and forward an inch or so. This will be easier to do with the gearshift in 1st/Low instead of Neutral.
2) Loosen/remove convertible top switch screws. There are two of them. Remove the LH screw. Loosen the RH screw.
1970 Cutlass Supreme convertible top swich screw location, as seen from the back.
3) Remove switch. The screw holes on the switch are open-ended. With the screws loose, just pull the switch out.
Reverse it all to re-install the switch. Make sure the part of the switch with the two terminals is on the top. Or else get a sharpie, cross out the word “Up” on the switch label and write “Dn” just below it, and vice versa.
My brother once said that I should just cut a notch in the brace to give clear access to the blocked screw for the next time the switch wears out. Yeah, ain’t gonna happen. First I’ll track down the designer of the car and ask, “why you make this so dumb?” The service manual doesn’t tell you that you should check the motor if your switch has gone bad. I’m telling you now. CHECK THE AMPS DRAW OF THE CONVERTIBLE TOP MOTOR IF YOUR TOP SWITCH IS GOING BAD! The top motor is designed to draw 30-35 amps when in operation. So is the switch. When the armature shorts out, the motor may draw 110-115 amps, like it did on my car. With great amps comes great heat.
Below is a picture of a top switch dismantled. It’s a very simple switch. Two sets of contacts, a button, and a nylon bushing that mounts inside the button. Press the button up or down and it pivots, allowing the nylon bushing to depress the proper contact and complete the circuit. Normally that nylon bushing is shaped like a lollipop. Take a look at it in the picture below. The dang thing got so hot, it melted the bushing to the contact. No wonder I couldn’t get my top to go up or down.
A convertible top switch from a 1970 Cutlass Supreme convertible, dismantled. It’s got a bit of damage.
A replacement switch costs anywhere from $60-100. If you know of a place to get these bushings, send me a message. I’ve got two switches sitting around that are perfectly fine but for this worn out melted sonofamajig.
This Old(s) Car 
Can I raise the top with switch bad to get it shut till I get a new awitch
You can raise the top manually, but because of the pressure of the hydraulics it will not be easy. The pump has bearing valves so you can do it, but go slowly. If you drain the hydraulic fluid from the system the top will go up and down easily, just like the mechanical tops on X-bodies. I wouldn’t recommend this over the long term, as there’s a chance you can throw the mechanics of the top out of alignment. If you do this make sure to cap off the pistons and the pump to prevent moisture from getting inside and wearing down components.
Question I was driving my cutlass convertible than I started having electrical issues my car would cut off battery would not charge I replaced battery n alternator car is not cutting of no more but my convertible top isn’t workin what could this mean? I recall at one point when I started my car if I tried to push switch to open an close the top it will cause the car to shut off