Fox T-Bird/Cougar Forums

Will this work and if not why? thanks

(http://i600.photobucket.com/albums/tt88/tomrenzo/DSCF2402_zpsbe32bfc2.jpg)

Nope. With both relays open your window motor has no path to ground. You need to reconfigure it without the diodes, and using the "87a" terminals on the relays. Connect both 87a's to ground. Feed your window motor from the "30" terminals. Connect the "87" terminals to power. Feed your relay coils via the up & down switches. I'd draw a pic but I'm using my phone. Basically what you want is for both sides of the window motor to be grounded at all times when the switch is at rest. Moving the switch to "up", energizing relay 1, provides power to the motor. Relay #2 remains grounded. Motor runs and puts the window up. Move the switch to "down" causes relay 1 to go to rest (grounded) while relay 2 goes "hot". Polarity is reversed, window goes down.

Like this


This method has the added benefit of keeping the full current of the window motors out of the switch - the switch is only carrying the current the relay coils draw. You can connect the "87" terminals on the relays directly to voltage (fused, of course, preferably with a self-resetting circuit breaker). The window switch can be connected to whatever power source you wish (BAT, ACC or RUN) depending on when you want the windows to operate

That is very good but i do not have a third  lead to the window in the door for then extra battery. Cant mess with the wiring on this car as it costs a lot of bucks. But it is a good circuit. I might run another battery like you designed but if the guy ever sells the car someone will notice it . let me think about it a bit. Thank you

Thinking about it i just might run the added battery lead!!

Tom, where is the window switch going to be located? If it's going to be in the dash or console you only need to run two wires into the door (the two motor leads), and you can mount the relays in the dash or console, or even hidden behind a kick panel. If it's going to be in the door, you still only need two leads (a power and a ground), you'd just need to mount the relays in the door as well. You can connect the battery feed to the relays and the switch feed to the same power source, you'll just have to be sure that the power source can handle the load of the power window motors.

This is for that Maserati, isn't it?

Yes it is. Here is what happened. The original window motor is obsolete. they only mad 16 of these cars. So what i did was install a Cadillac motor. But the Caddy motor uses 2 leads and swaps them for up and down. The Maserati has the motor grounded by the case and uses battery in one leg then battery on the other to reverse directions.  So i am going to use Thunders print not because my does not work it does. but i would need a diode that could handle the 15Amps. Also his print does not put high current through the switches. Which are already rebuilt and totally obsolete as well. So i am going to use his print. it is a good one. I am going to mount the relays in the dash and use 2 leads as you suggested. Thanks

Thank you for helping me well appreciated Thunder

On looking at your diagram again, you're right, it would work. My bad, I wasn't even thinking about powering the motor through the diodes. I probably even have a bunch of high current diodes kicking around here... 1N540X maybe (the x could be anything from 0-8, the higher the number the higher the voltage the diodes can handle but since the lowest is 20v, any would do for automotive applications). Regardless, it's probably better to keep the current out of those switches...

This is why I could never own a rare or valuable car. The temptation to re-engineer ancient ideas would be in constant battle to keep the car original (and thus valuable). I love antique technology, will spend hours watching century old engines running on YouTube, but I like my electronics modern. And working. And for some reason, probably coming from my experiences with Ford ignition switches, I hate the idea of a switch carrying heavy current...

I know Jack Schitt about car electronics, but having one switch catch fire on me, and replacing half a dozen or so other ones that were well past needing it, I fully agree. Kinda like not putting an HO in the Sport and XR7 cars...it's one of those..."what in the actual fawk were they thinking?" things...

You know just for kicks we were on VOLICITY last night. They did not feature this car but featured a 512. You can see the Maserati in the background. You know people always ask me if i have fun driving these cars around. And i do. But believe me driving them is far from FUN, God Forbid someone blows a stop sign. Also these cars are CRUDE. The welds are garbage they always leak and the electronics suck. Ferrari for example has a complete point ignition on standby right in the car to swap over the electronic system because they are so bad. We convert them to believe it or not to MSD. This makes them reliable. You can not use second gear till they worm up but after that WOW. You shift from first to third till it heats up. They need Racing fuels of at least 100 Octane we keep on hand.  But they are as fast as hell handle like they are welded to the pavement. They turn heads better than any car on the planet and they are extreamly hard to work on.  Thanks Thunder you were a big help. Today i am installing you circuit. Have a good day