Weird electrical problem?

B

Bobs29ModelA

Senior Member
The other day, I was able to crank my stock '29 Model A, but it wouldn't start, and I eventually ran the battery down to the point of the cranking being very sluggish. This was unusual, as it's electical system is fully stock (6-volt positive ground), with the exception of having a 6-volt Alternator in it.. and it's never given me any problems. It appeared to be getting fuel OK, but was symptomatic of no spark being present. After putting the battery on the charger for a couple of hours, the car cranked and started without any problems.

Today (a few days later), I went to see how the car/battery was doing, and it cranked and started up again just fine.

However, I've now noticed a couple of new, weird symptoms... first, unless the car is actually running, you cannot get ANY of the lights or the horn to work with just the ignition key on... not even the small dash light! No cowl lights, no horn, no headlights, no tail-lights, no nothing. However, the car WILL still crank just fine (as if it has a fully-charged battery) and, once the engine is running, the lights pop-on after a second or two.

As a side note, I also noticed that the reading on the ammeter remains at zero, no matter what you do. I'm not sure if this has anything to do with the problem; however, I removed the ammeter, just to take it out of the equation (in case it was causing a short somewhere) but the no-light symptoms remained unchanged.

If anybody has run into this weird situation, your thoughts would be much appreciated. Thanks!
 
Ignition Key on ONLY energizes the engine firing circuits. Everything else should work identically with ignition ON or OFF - or engine running or stopped.

I would check your connection between the generator all the way back to the battery ground.

Joe K
 
I suspect your battery is not seeing a good solid ground. Take the battery ground cable off and clean the attachment boss on the frame and clean the cable as well.

Tom Endy
 
bob needs some more help,maybe tom w. will be along soon. also he said he is running an alternator. tom in Joppa md
 
If the car is cranking over I'd guess the ground is good. Check and see if your alternator's batt term. is live. Use a voltmeter and a light. The engine does not need to be running. Are there three wires on the alt batt term?
 

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Tom Endy said:
I suspect your battery is not seeing a good solid ground. Take the battery ground cable off and clean the attachment boss on the frame and clean the cable as well.

Tom Endy
Click to expand...
I concur, poor grounds on any system do weird things. Like others have asked do you have the common add a fuse that bolts to the starter? They have been known to vibrate the rivets loose causing issues.

Do the following with the battery cables off the battery:

Id check all the connections (there arent too many) and just have a looksie and lightly attempt to tighten then especially the ones on the back of the ammeter since they all run thru it. If you see rust/corrosion/or alot of paint clean any iffy ones up and reconnect. id start at the starter stud since you say you ALWAYS have power to the starter when you try but no power to anything else. (all tied from that point - go until you don't have power, my guess would be behind the instrument panel is your culprit)

If you have a repo ammeter they are known to be of iffy quality on the insides so while the nuts may be tight on the backside the studs may not be tight on the inside causing a poor connection/open connection.

In the meantime Id keep the battery cable off the battery or keep the disconnect off just in case something decides to ground out and start a fire.
 
Let's take a look at the diagram the Willie posted. In place of the cut out and generator there is an alt. It is from this point, the alt connection, that the lights and horn get it power from the direction of the battery until the alt is running then from the alt when the engine is running. The starting and the ign come from the battery and does not need the alt.

Your symptoms are that the starting and engine will run, see the yellow wire on the drawing from the starter. The lights and horn only work when the alt is working, see the yellow wires on drawing from the cutout.

My guess is that your battery is not charging as well. I would check the "black/yellow" wire and the terminal on both sides to see if there is a good connection as this wire is the one that "joins" the battery and alt.
 
Just had samr problem on custmers car that had all worked but during lhd to rhd etc found no power at light switch , lights , horn etc , but would turn over ok, problem was amp meter stuffed , plus dash wiring suspect , new bits all fixed , T box & ampmeter , KEEP your NUTS tight, Thats my take on it,
 
Me again; thanks for all the input.

I should have mentioned that I checked the battery posts for any corrosion (nothing wrong there; still clean and shiny), and water levels in the three cells were fine... as well as I removed the dash panel and checked for any abrasions on the back of anything that might have rubbed a short onto the gas tank, and everything looked good. I also checked the connections on output lug on the back of the alternator (all wires clean and solid), so nothing obvious there. And, yes, I do have that aftermarket fuse holder and fuse mounted on the starter, and all of that was still clean and tight, and the fuse was good.

As mentioned earlier, I also removed the repop ammeter just for fun (had voltage across the two ammeter wires), so even though the ammeter may no longer be reading (as in, gone bad), removing it from the equation did nothing to solve the problem.

The one other thing I did notice today is that my charger (6 volts, 6 amps) used to read at a particular charging rate (shown as a percentage on the charger's gauge), which is then supposed to work it's way up to finally show a 100% charge (which it used to do in the past). Curiously, it now only levels-off at the 50% charge level, and stays at that level, no matter how long you keep it on the charger.

Because of this, my first thought was that the battery is going bad (almost 3 years old now), because it doesn't seem to want to recharge fully... but, if that is the case, why would it crank so perfectly, yet not run any of the accessories with the engine off? This all seems backwards to me...
 
Hi there Bob, I had similar probs with the same set up on our 30 phaeton and found the wires in the fuse link at the starter ie the main supply to all the electrics had a poor connection so cleaned up the fuse and soldered the wire joints and all is well.
Hope this is of some help. Happy motoring
 
I've seen glass fuses look good, but have a bad connection just inside the metal cap. You can use your short clip lead (everyone should have a couple) to bypass the fuse by clipping on the starter switch stud and to the yellow wire going up to the terminal box. See if this makes a difference.

If the car has been parked for some time during humid weather, the points may be oxidized.

Once the car is running take a voltage reading at the alternator post, each terminal box post, the starter switch, and finally at the battery post. Let us know what the readings are.
 
The smoking gun in this is that the lights don't work unless the motor is running and therefore, the alternator. Another clue is no charging indication with the motor running, and he had to use an external charger to charge the battery.

Using an ohm meter, check for continuity between the lug on the back of the alternator and the battery post. My guess is there is a problem between the alternator and battery.
 
Thanks; I will continue to look into this when I have more time available, and will update once I have something to report.

(BTW, points are not a consideration in this equation, as my car has an FS Zipper electronic distributor installed).
 
Friend, Chuck, had a BAD connection at the junction box, even though the nuts were VERY tight & NO visable signs of corrosion! He added star washers & tightened them well & problem was fixed!
Bill W.
 
Your ampere meter is part of the complete electrical wire loop from the charging unit to the battery. It has no ohm resistance. Take one wire off of the amp meter and check for continuity across the unit. Should have no resistance.
Dave
 
Have you checked the water levels in the battery in case the electrolyte levels have gotten too low and the battery may not hold a charge for an extended period?
Maybe the load of the lights is too high unless there's current being assisted by the alternator.

If the battery is going south, you don't want to overwork your alternator.
 
A poor connection means high resistence, which leads to heat. You can make a quick check by touching each connection to see if it's hot.

Alternator output stud
2 terminal box studs
2 fuse ends
starter switch stud
battery posts
Ground connection for battery cable
 
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