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Top Motor Troubles

timbeam

Member
I thought I would have my convertible top issue fixed today, but it still is not working. The red wire at the motor is showing 12 volts when the switch is moved in one direction and the yellow is reading 12 volts when it is moved to the other. This made me believe that the motor was bad, so I went over to Dallas Mustang and picked up a new one. I swapped the connector (the new motor has the late model connector), installed the lines, wires and filled it with Transmission Fluid (stopped at Walmart on the way home and bought a Turkey Baster). I expected it to work and... nothing. Still getting 12 volts to the wires but the motor is just not running. Am I missing something? I doubt that this new motor is bad, now I am doubting my old one was bad. I hope I didn't just waste almost $300 - convertible motors are not cheap!
 
I checked the place it's grounded and it show continuity to the chassis. I even took a test lead (wire with alligator clips on each side) and ran it to another ground point. Still nothing...
 
I am thinking that even though I am getting 12 volts on both leads, it must not be providing enough current to run the motor. Since this is running straight from the battery, through a 20 circuit breaker, to the switch, then to the motor, I am thinking the only thing that could be dropping the current is the switch. Does this logic sound feasible?
 
There's a way to check for current to the top, but it is kind of risky. Instead, can you bypass the switch itself with alligator clips and some large diameter wires (not speaker wires) and see if the motor runs?

As to your question, yes, the current draw can cause the voltage to drop at the motor. Is there any way you can measure the voltage at the motor while using the switch to power the motor?
 
I did something along those lines. I hooked the motor up straight to the battery and used ammeter (across the fuse holder) to complete the circuit. It ran momentarily but the breaker on the meter pops at 10A. My guess is the motor is pulling above 15 amps. I guess I should order a new switch. This one is a reproduction only a couple of years old. Ouch!

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1966 power tops use a 20 amp circuit breaker. Ford usually built in a 100% safety margin on wiring, so your motor should pull about 10 amps. I'm beginning to think your motor is bad or there is an excessive load there.
 
I am going to pick up a few fuses for my test rig - a 10, 12 maybe a 15. I went ahead and ordered a new switch too. The switch I have is of very marginal quality so it's still good to replace it anyway with a Scott Drake which should be more on par with the original.
 
I haven't disconnected the rams. I think it would though. The top always worked before the motor quit responding to the switch.
 
Sounds reasonable......but......if the top slowly bound up in the joints, it could cause the drag on the motor. You may not have noticed the slow change in the top action.
 
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