Everything but starter
- Thread starter Tom B.
- Start date
Patrick L.
Well-known member
Time to buy yourself a test light and look at a wiring diagram. [ maybe someone will post one]. Its simple system. Start at the starter and work thru the system looking to find where the voltage disappears. If your car happens to have one of those aftermarket fuses at the starter it could be a simple as a blown fuse. But, then the question is why did the fuse blow.
KGBnut
Well-known member
The way things are usually wired, a heavy cable goes from the battery to the starter, then a lighter wire goes from the starter to the rest of the car. If EVERYTHING else it out, it sounds like your problem is there. I think that wire goes directly to the terminal box.
Also, as Patrick points out, it is pretty common to put a fuse on the wire coming off the starter, and some people hide that fuse on the inside of the firewall, behind the terminal box. As he mentioned, if you find a blown fuse, you need to try and figure out why it popped.
I don't have one handy, but if you look look at some other threads you can find a full wiring diagram.
Ken
Also, as Patrick points out, it is pretty common to put a fuse on the wire coming off the starter, and some people hide that fuse on the inside of the firewall, behind the terminal box. As he mentioned, if you find a blown fuse, you need to try and figure out why it popped.
I don't have one handy, but if you look look at some other threads you can find a full wiring diagram.
Ken
BILL WILLIAMSON
Well-known member
Tom B,
DON'T let an electrical problem BOMB you out. With a wiring diagram & a test light, you CAN find it.
"Usually", the actual repair is QUITE SIMPLE.
Bill Arc
DON'T let an electrical problem BOMB you out. With a wiring diagram & a test light, you CAN find it.
"Usually", the actual repair is QUITE SIMPLE.
Bill Arc
Growley bear
Well-known member
I was working on a Model A one time, not an electrical problem. While I was standing beside the car with the hood up and engine running all seemed to be going quite well. Then the engine quit. Now what? The 12v starter whirled the engine over like no one's business. Hmmm no power past the starter. In reference to the wiring diagram in a previous post, the problem occurred at the main power connection on the starter switch. Refer to the solid yellow wire from the starter to the ammeter in the diagram and the solder connection between the wire and the eye connector at the starter switch lug was faulty. It looked great but wasn't. No voltage in the wire adjacent to the connector. The connector was HOT but the wire wasn't.
A good wiring diagram and a test light are essential basic tools for troubleshooting electrical issues.
A good wiring diagram and a test light are essential basic tools for troubleshooting electrical issues.
Tom Wesenberg
Well-known member
Clip the test light to a good ground, then probe both sides of the fuse, if it has one, then probe both terminal box wing nuts. This will only take about 5 seconds, and most likely will have already indicated where the problem is.
No light on one side of the fuse, it's blown or loose.
No light on one side of the terminal box, it's a poor connection inside the terminal box studs or the ammeter studs.
This assumes you have a good harness with soldered terminals.
If they are simply crimped, then they can be bad but look good.
No light on one side of the fuse, it's blown or loose.
No light on one side of the terminal box, it's a poor connection inside the terminal box studs or the ammeter studs.
This assumes you have a good harness with soldered terminals.
If they are simply crimped, then they can be bad but look good.
Tom Wesenberg
Well-known member
And the problem was? 
Patrick L.
Well-known member
Yes, you bet ! The problem was what ? You can't just say something like that, ya got ta tell us.
Jeff/Illinois
Well-known member
I'm chasing a gremlin myself. Test light on at starter switch, both sides of fuse, both terminal box posts, both ammeter posts, and hot at the generator output. Original points cutout and original ammeter. 6V positive ground as original, using an Autolite long generator. 1930 Model A. Started two weeks ago when the ammeter needle was bouncing wildly back and forth from Discharge to Charge. Then wouldn't show 'charge' anymore. Only discharge.
Each of the above connections shows 6.4V 6.4V at battery too. Did a continuity test on the cutout it's OK. also on the yellow wire circuit no open circuits but since it is hot I figured it has to be working anyway. Same with ammeter not shorted out. I haven't fooled with the ignition side there is power to the ignition switch and on both terminals with switch 'on'. Car starts and runs fine. I've used two known professionally rebuilt gennies and they are both working fine.
My problem is ammeter not showing a charge. Have tried a spare reproduction ammeter same thing. 'New' original ammeter shows a 'charge' when you throw the lights on. Tom W. told me that it may be a Model T ammeter (negative ground) or someone put the magnetic ring in opposite, and switch the wires at the ammeter. Still won't show a charge.
Drug out a book I've had since 1972 by Mary Moline 'Model A Miseries and Cures' and it says it is one of four things: 1.)bad generator 2.) bad cutout 3.) bad ammeter or 4.) open circuit i.e., yellow wire or yellow wire with black tracer.
Hot today got up to 90. I stopped working on the car early afternoon. Never lost my patience taking it a step at a time. Will get back on it probably Thursday.
But it's got me scratching my head
I've done the basics, three times same results, somehow I'm missing something it has to be simple. Since I'm getting good voltage all over the place, have swapped out (one at a time) known good ammeters-cutout-generators still no go, I'm stumped.
If I find it I will post the results. Only thing left to do at this point is call in a priest and hold an exorcism on the old girl.
Each of the above connections shows 6.4V 6.4V at battery too. Did a continuity test on the cutout it's OK. also on the yellow wire circuit no open circuits but since it is hot I figured it has to be working anyway. Same with ammeter not shorted out. I haven't fooled with the ignition side there is power to the ignition switch and on both terminals with switch 'on'. Car starts and runs fine. I've used two known professionally rebuilt gennies and they are both working fine.
My problem is ammeter not showing a charge. Have tried a spare reproduction ammeter same thing. 'New' original ammeter shows a 'charge' when you throw the lights on. Tom W. told me that it may be a Model T ammeter (negative ground) or someone put the magnetic ring in opposite, and switch the wires at the ammeter. Still won't show a charge.
Drug out a book I've had since 1972 by Mary Moline 'Model A Miseries and Cures' and it says it is one of four things: 1.)bad generator 2.) bad cutout 3.) bad ammeter or 4.) open circuit i.e., yellow wire or yellow wire with black tracer.
Hot today got up to 90. I stopped working on the car early afternoon. Never lost my patience taking it a step at a time. Will get back on it probably Thursday.
But it's got me scratching my head
I've done the basics, three times same results, somehow I'm missing something it has to be simple. Since I'm getting good voltage all over the place, have swapped out (one at a time) known good ammeters-cutout-generators still no go, I'm stumped. If I find it I will post the results. Only thing left to do at this point is call in a priest and hold an exorcism on the old girl.
Tom Wesenberg
Well-known member
Engine off, turn on the headlights and blow the horn. If both work fine, then the connections should be good all the way up to the cutout, where the lights and horn pick up the power.
Easy check for the generator working. Turn the lights on with the engine running at fast idle. Leave the lights on and turn off the engine. If the lights dim slightly, the generator was working. An accurate check is to measure the voltage at the output side of the cutout with the engine off, then see if it increases a few tenths with the engine running at fast idle.
Remember, when using a voltage regulator, the ammeter will remain barely above zero when the battery is fully charged.
If you have any doubts about which cutout you have, use an ohm meter between the case and input terminal. A stock cutout should show about 40 ohms, a repro cutout should show 20 to 30 ohms, and a diode cutout should show open (infinity).
Easy check for the generator working. Turn the lights on with the engine running at fast idle. Leave the lights on and turn off the engine. If the lights dim slightly, the generator was working. An accurate check is to measure the voltage at the output side of the cutout with the engine off, then see if it increases a few tenths with the engine running at fast idle.
Remember, when using a voltage regulator, the ammeter will remain barely above zero when the battery is fully charged.
If you have any doubts about which cutout you have, use an ohm meter between the case and input terminal. A stock cutout should show about 40 ohms, a repro cutout should show 20 to 30 ohms, and a diode cutout should show open (infinity).
Jeff/Illinois
Well-known member
Thanks Tom I'll do this.
The headlites low beam and hi beam and horn work fine, as do cowl lights and tail lite
I did an Ohm reading on the cutout like you suggested, and wrote it down but left the paper out in the garage. I don't recall the figures off hand but there was resistance as I recall so didn't dwell too long there. I'll re-check that too. I was hoping to find infinity and beyond (or is that a Buzz Lightyear saying from Toy Story?). Didn't check the diode cutout it's over in the bigger garage in my parts stash I'll get it back over too.
On a finer note, the '36 pickup is running better than it ever has AND I just packed the steering box with JD Corn Head grease. I'm sold! Took the '36 out for a drive today and it has never steered so well in the ten years I've owned it
No more Exxon Valdez re-enactment of 600W on my garage floor with that bad boy!
The headlites low beam and hi beam and horn work fine, as do cowl lights and tail lite
I did an Ohm reading on the cutout like you suggested, and wrote it down but left the paper out in the garage. I don't recall the figures off hand but there was resistance as I recall so didn't dwell too long there. I'll re-check that too. I was hoping to find infinity and beyond (or is that a Buzz Lightyear saying from Toy Story?). Didn't check the diode cutout it's over in the bigger garage in my parts stash I'll get it back over too.
On a finer note, the '36 pickup is running better than it ever has AND I just packed the steering box with JD Corn Head grease. I'm sold! Took the '36 out for a drive today and it has never steered so well in the ten years I've owned it
No more Exxon Valdez re-enactment of 600W on my garage floor with that bad boy!