Starter button explaination

[rockfla]

Okay I need some help understanding starter buttons. I am suspecting my starter button "might' be my issue on my 39 Merc. I was under the dash as best my big head could fit under the small space between the floor board and the back of the dash but the bottom lip of the dash curing back still blocked a clear view of my starter button. Feeling behind the button I felt only one wire coming in (or out) of it? SO looking at Michael's page and the possible need to get a new "button"....the button he has listed shows ONE wire coming in (or going out) Pic's 1 & 2. MY simple mind is asking JUST how does a "single" wire work because to my simplistic thinking, the button is the "basic" connection FOR power in....power out...SO one wire in and one wire out (see pic #3).....how does the "ONE" wire button work???? OR how do I meter/continuity check my button to see IF it is actually "Buttoning"??? Even IF the button operates through "grounding" a single hot wire? the power has to come from the "source" ie the battery......HOW do it tell the starter to "START"???? Doesn't there have to have a wire to the starter/solenoid???

[Karl Wescott]

The switch is designed to ground through the dash. If paint, bondo, or rust has insulated the dash the circuit will not be completed.


Try removing the wire from the switch and shorting the wire to known ground, if things work its the switch or ground connection. Now, with the switch out of the dash clamp a wire to ground to the switch housing. Try the switch. If thing works its likely a ground problem, if not likely a switch problem.


If the switch is good then consider soldering a ground wire to the switch housing (making it a two terminal switch). A best practice "street rodders" use is to run a heavy gauge wire across the dash grounded on both sides, then connect ground on any switch or gauge to the ground wire.

[Kube]

Be aware that the reproduction buttons are 100% crap. Find a NOS or a NORS on eBay.
Karl makes a VERY good point about the grounding concern. When I did each of my restorations, I would solder a short wire to the body of the switch (button) and run that wire to a nearby bolt that was free of paint. I was able to hide that wire for judging purposes. Even with NOS switches, it was amazing the difference this little wire made.

[rockfla]

Thank you Karl


I understand the whole button being the "grounding" point in the system.....SO I would assume the one wire coming into the switch is constant power? switch on or off the button has constant 6V coming in??? SO I would ALSO assume that the "same" single wire is what goes to the small machine screw thread post on the starter solenoid?? SO "IF" my two assumptions are correct??? WHERE does the 6V ie connection to the battery come in??? OR the one wire acts as the Grounding point (OR Is connected to the battery side of the solenoid for constant power AND when grounded makes the connection for the starter side of the solenoid) for the battery wire to the solenoid and the solenoid to the starter??

[rockfla]

Originally Posted by Kube

Be aware that the reproduction buttons are 100% crap. Find a NOS or a NORS on eBay.
Karl makes a VERY good point about the grounding concern. When I did each of my restorations, I would solder a short wire to the body of the switch (button) and run that wire to a nearby bolt that was free of paint. I was able to hide that wire for judging purposes. Even with NOS switches, it was amazing the difference this little wire made.

Thanks Michael, I am having to do that with my Prototype WWII jeep as they are known for both not enough and poor grounding overall. I also had to ADD extra grounds for the body to frame as well on it!!!

As for the Mercury its just curious, to me, how for 17 plus years of owning the this car, I haven't had issue one, nothing......and NOW....Lol how or why NOW if its a grounding issue?? I guess as one of good friends says "It's one of those Mysteries Of Life deals"

[hueyhoolihan]

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IOW, the body of the switch is "the second wire" that connects back to the battery through the metal dashboard and the battery's ground terminal. occasionally, on older cars, the switch will fail to work because the body of the switch and/or the metal around the hole in the dashboard can get corroded or "wallered out". mid-western expression, over time. ha

of course, the switch itself can also fail internally.

BTW, if and when replacing the switch (i put a new one in just a couple of months ago) it's a good idea to disconnect the battery, as the starter switch will likely ground itself, but more likely the bare wire that runs to it, constantly during installation and in turn activate the starter motor!!...very annoying.

[glennpm]

Karl's description is spot on. You can test the button without removing it or it's wire with a multi meter easily. Ground one lead from the multi to a known good ground and touch the other wire from the multi to the chrome bezel. With the button depressed you should have a very low number or zero on the multi-meter. This will tell you if the switch is properly grounded. To check the switch, move the multi wire from the known good source to the start button terminal on the solonoid.

[Ken/Alabama]

Connect a wire to the small post on the starter switch on the firewall then touch the other end to the positive post on the battery, if you still have positive ground system, and see if the starter engages. If so then your problem lies within the starter button not grounding or the wire itself. Also , one of the large post on the starter switch should be marked “Batt” make sure it’s connected correctly.

[GB SISSON]

I think some of the confusion comes from the fact that many starter solenoids in common use require a 'hot' connection to the small post to get the solenoid to do it's click and energize the starter. I have a drawer with maybe 8 solenoids in it. I'd say half of them work by getting juice from a hot wire through a normal 'wire in, wire out' switch. The other half are from flatheads and those odd solenoids do their trick by grounding out the small terminal. Flathead= ground the terminal, conventional= hot up the terminal. Many years ago I wired up one of my trucks with the wrong type of solenoid so I just ran a conventional momentary 12v switch and 12v to the battery. Worked great, but always confused me when troubleshooting, so found a correct solenoid at swap meet and went back.

[tubman]

When I built my engine "run stand", I made is so I could run either 6 volt positive ground or 12 volt negative ground engines (believe me, it was a difficult task when you want to run full instrumentation (including a tachometer and an O2 meter). One thing that never gave me a bit of trouble was the starter solenoid. I used a 12 volt unit I had laying around and it has performed flawlessly for over 10 years in both scenarios.

[V8 Bob]

I use a high quality two-contact momentary push button starter switch on my '32 and '40 from NAPA, O'Reilly etc, Standard SSB-1 or SSB-1. Commonly used on '37-'51 Fords, designed for 12V negative ground, but can be used in a 6V positive ground system by simply running one of the contacts to ground, as the switch body is isolated. One of the advantages is ensuring a good positive ground with a painted dash.