So I've inherited a 1948 Buick Special convertible. Having issues with the power windows, seat and top. I'm convinced the car is still setup for 6 volt. With 6 volt battery, car runs great and puts out 6.9 volts to the battery. Car running, I push button for window down and window goes down. Push button window up, window goes down. This solenoid is installed at bottom of pass. firewall and there's another one sitting loose in the trunk. Makes me wonder if PO bought it to replace but never got around to it. Before i start swapping parts, can anyone help me understand what this is for and what it might do? Perhaps a schematic? I've tried contacting the vendor on the label with no luck. Sent from my SM-G930V using Tapatalk
there's a little label on there that would tell us what it does, if only you would turn the thing a little bit and take another picture, so we can read it!
The label only has the supplier's contact info. I've been trying to contact them to no avail. Didn't want to publish their name on line Sent from my SM-G930V using Tapatalk
Correct me if I'm wrong but isn't everything operated off a hydraulic pump on those? That solenoid is probably the control for the hydraulic pump, which was usually mounted on the firewall (at least on the 2 Cadillacs I've dealt with). Pushing the down button just releases the the hydraulic pressure, you should be hearing the pump run when up is pushed. Here is some info I found when searching for a diagram that may help- http://www.antiqueolds.org/PDF/hydro-electric.pdf
Ok, well, now we know! My first thing would be to get the factory shop manual for the car, and then see what it has to say about how the power window system works. Or else take a very close look a how it is all made, and try to figure out how it works.
Can you get some pictures of the firewall? Here is some more I found, Cadillac but the basic principles should apply- http://www.1949cadillac.com/category/hydro-lectrics/
The system is powered through the ignition switch, to a circuit breaker and on to the switches but I think since your windows are going down that part is ok. Check the solenoid/relay mounted on the pump (lower left side of firewall), you should have power to the small wire when any switch is operated up (key on). Also check that you have battery power to the solenoid and through it when up is called for. Everything you ever wanted to know about 48 Buick hydraulics- http://buick.oldcarmanualproject.com/manuals/1948/Buick shop manual/13-Body/page1.html
^^^ Beat me to it. The old GMs ran electro hydraulic tops, seats and windows. Here's the Fisher body manual. It's very crude or simplistic by today's modern standards however it was cutting edge technology at the time.
The solenoid you have is a series parallel switch. These change the way 2 batteries are connected to provide 12 volts for cranking and back to 6 volts when not cranking. Does it have two 6 volt batteries now or look like it did at one time? http://www.texasindustrialelectric.com/relays_1119845_6V.asp
Looks like a part of a 6-12 volt battery they make; according to the Antique Auto Battery's web sight. Thought it looked like a parallel switch, too.
Thanks for all the support. Looks like I have 2 different issues. I have added ATF to the hydraulic system and now can get the pump to activate and work the windows on a 12V battery but not on the 6V. I even tried with the car running and charging @ 6.9Vs but no go on the pump. Based on the schematic that 24Riverview clued me into, the existing parallel switch appears to be wired wrong, which explains that dead shorted / melted wire I found... I'm certainly learning a lot. Thanks again.
Does the relay on the pump "kick" in on 6 volts but the pump doesn't run or does it not? Someone may have changed the relay in the past and put a 12 volt on by mistake, not sure how 12 volt relay would react to only 6 volt.
The company that's name is on the series parallel switch made that to go with a 12 volt battery that had center taps to act as the two 6 volt batteries in the previously linked schematic. It's purpose was 12 volt start, 6 volt run. For it to function you need either two 6 volt batteries or the specially tapped 12 volt battery. Since you said the charging system is still 6 volts; and unless you see a bunch of added wiring; I would tend to believe that your window system was still 6 volts as the car is. Since it sounds like you don't know what the previous owners have done; I would look at the relays and solenoid valves for any markings. 12 volt components will be marked; 6 volt may or not be marked. Once you have that established; just troubleshoot each piece, proper voltage, no excessive voltage drop under load, good ground, and electro/mechanical function.
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