Re: Convertible top control 101

Posted by HH56 On 2021/1/25 11:22:17

On 48-54 models there is a circuit breaker and a solenoid on the side of the pump motor. The power comes directly from the battery via a connection on the starter solenoid and thru the CB to the various window (or top) switches. The switches in turn operate the solenoid to turn on the motor. The motor only runs in one direction and pressurizes the lines. While it does not show on the diagrams, on some cars there is also a relay operated by the ign sw. Its contacts are in series with the wire protected by the CB to prevent any window or top operation when the key is off.

For the convertible, there is an electrical switch mounted on the top of a valve mechanism that is in turn bolted to the firewall. The knob connects to a rod which operates the valve and switch mechanism.

As the pump only operates in one direction -- to supply pressure to the lines -- for the top to raise or lower, the valve portion of the assy directs fluid to the top or bottom of the top cylinders at the same time it turns on the pump.

On cars that also have hydraulic window operation, when raising the windows the switches commands both the pump and a solenoid valve at each window cylinder. The pump motor provides pressure to raise the window or move the seat forward. The top is not affected when raising windows because the top valve remains closed just the same as the windows are not affected when the top is operated because their cylinder solenoid valves remain closed.

To lower the windows or move the seat back the switch only operates the solenoid valve at the cylinders. Without pump pressure a large spring and gravity lowers the window or moves the seat back.