Re: Push Button Auto L and D have disappeared

Posted by HH56 On 2024/6/3 9:18:42

And if it does turn out to be electrical and the actuator is not moving when D or L is pushed, before going under to check fingers check the contacts on the back of the pushbuttons. A flat leaf contact on either side of a button is connected together when the button is depressed and a spring clip around the button stem touches the two of them simultaneously. The vertical leaf has a sharp bend and metal fatigue has been known to weaken so one cannot make contact or one completely breaks off. A faulty leaf contact will only disable that particular button.

Someone long ago devised a repair using miniature microswitches to replace a broken leaf. Riki did the mod on one of his switches a couple of years ago but used a piece of aluminum angle for the support rather than bending the recommended shim stock. While the aluminum is a bit thicker than the original design called for it worked out. He also made a change in the way the reverse lights and starting relay is activated. Some photos are in his blog.

I would post the original design paper which has some detailed instructions but as I recall it came from something PI published in the 70 or 80s so may still be copyrighted.