Tagged: Electrical, roubleshooting
So… I made a mistake with a 12 volt jump starter and fried my ammeter causing it to create a short in my wiring system. Obviously I’m not an electrical expert and I now have a couple questions. Is it a problem to run with the ammeter disconnected until I get a replacemnt? 2nd question, does anyone know were to get a replacement?
I expect there is another root cause to the short circuit problem than the ammeter itself; look for a bad wire or other power consuming device that has an accidental ground connection. I also use and recommend these three tools to help your search:
1) The Pierce Arrow Wiring and Tuneup Guide [on our website: Member Pages -> Company store -> Book Gallery ->(last row of books, on the right side)]. I have one of these books for sorting out wire problems on my ’29, and it is very useful.
2) A Voltage/continuity meter; to measure resistance to ground of individual wires and devices, you don’t need an expensive one. If you find something touching ground that should not be, then it becomes very high on the list of suspects.
3) Test Battery. I use the Rayovac #918, a 6 volt lantern battery with screw terminals to connect your test wires. This battery has enough juice to make many accurate tests – but not so much power it is likely to fry something else. The battery in the car has too many amps for testing, and is not good at testing individual wires or devices.
Happy Hunting, Herb
The 6v Rayovac battery is an excellent suggestion for testing your wiring.
Also remember that your Pierce is a POSITIVE GROUND car.
A good source for 6V ammeters is eBay.
I believe that I just bought one there today.
Thanks Herb and Peter for the excellent advice!
Give us a little more information. Are you saying that the ammeter shorted out internally or that there is a short somewhere in the electrical system that you need to find?
What did your ammeter do that makes you think it is shorted? If an ammeter shorts internally between the terminals it usually just stops working but everything else will work, unless it shorted to the case. If it failed open, then everything except the starter will be dead. You can usually bypass the ammeter. What lead to this? It is possible you may have more problems than the ammeter.
Check with Greg Long about where to find a replacement.
See the attached picture of the back of my. The burnt post had a wire running to my starter. I disconnected this wire and the short to my frame went away.
So I figured when it burnt I shorted out internally and to the frame. Well, I just went out to test the burnt terminal to the frame and it’s an open circuit, no short. I also tested between the 2 ammeter terminals and it is almost shorted reading about 1 ohm. Which I think is ok?
I thought that maybe the wire that runs from the ammeter to the starter must be shorted. It is not shorted.
The only thing I’m finding shorted to the frame is the positive battery terminal. As it should be.
After looking at the back of the ammeter, I see evidence that the wire attached to the burnt post had arched to the case of the ammeter causing the short.
That would do it. According to the S80 wiring diagram, the wire from the starter should be the hot from the battery so if it shorted to the case of the ammeter there were probably some sparks. You mention the post to case is an open. Check the condition of the insulator on the ammeter post and then check the posts of the ammeter with your ohmmeter to the case while wiggling the post and see if they short, just in case an insulator was damaged. Found the sound of it, the wire from the starter to the ammeter would have taken the current surge. Any damage to the ammeter would have been from heat. It sounds like you should replace the wire, check for shorts with your ohmmeter and then see how things work. Possibly your ammeter is OK.
The right post looks like it has a nut or spacer under the the wire end. Was there one on the left post? If that is missing, the wire end would be closer to the case possibly allowing the short to the case. Maybe the extra voltage from the 12v jump was enough to initiate the short.
Judging from the wire in the upper right of your photo, it would be a good idea to check the condition of all of your wiring.
Good idea to check that the insulator is ok. I’ll add a plastic spacer to the shorted side to help keep it insulated and away from the case.
My wiring is a mess! I have a lot to redo. It starts and runs great, but basically nothing else electrical works.
Just in case you need a new gauge, you can look on eBay for a “Vintage AMPERES” gauge.
There are at least a dozen currently (no pun) available on eBay, although the faces on some are WHITE.
I believe that you can always remove the faceplate with a very ting screwdriver, and replace it with the Black one from your Pierce-Arrow.
The Packard, Amperes / Oil Pressure gauge set is near identical in shape, size and configuration, perhaps, save for color, as that on the Pierce-Arrow.
Some have Black faces.
It will be good for you to start collecting replacement parts, especially electrical parts, for your Series 80, as they are increasingly difficult to find and you should snag them when you see them.
Just don’t tell your wife!
Apropos of the wiring on the car, it will not be that difficult.
You need to buy a number of different colored rolls of electrical wire.
Get one in Black and one in Red, and then a few that are multi-colored rolls which come with White or Black tracers.
I recall that the most difficult wiring is behind the dashboard, as you may have to be lying on your back on the floor and working upward.
The headlight and taillight run is relatively simple, although you need to run it through the conduit that runs fore to aft.
I don’t totally recall, but I may have had to run a nylon string, or just SS-wire through the conduit first and then affix the electrical wire to the nylon string or SS-wire and carefully pull it through.
At least in that way, you know that all of your wiring is new.
The one wire that I did not replace was the wire that runs to the interiorDome Light, as it may require removing some of the “B-Pillar” upholstery to do it.
I rarely use that light anyway.
Restoration Supply and other vendors carry that type wire. https://restorationstuff.com
As for the gauge, I do not recall (a mind is a terrible thing to lose!), however I believe for MOST applications will require 12- to 14-gauge wire.
For some of the direct to Battery leads may require 16 t0 18-gauge wire.
If I am wrong, I am confident that someone here will correct me.
If you ave any questions on any of this, please feel free to telephone.
Hello Jason. I think I have an idea how your wire burn up. Did you hook the 12v jumper cables directly to the battery under the floor? or to the battery cable connection on the starter switch box stud?
If you hooked up at the top of the starter, on the switch box stud, then it is possible that your jumper cable clamp did not contact the battery cable, but DID contact the smaller wire going from the stud through the firewall then to the ammeter. When you tried to start the car, there would be a lot of amperage going through that wire. I need to think on this again.. Is there any chance you put the 12v jumpers on as on a negative ground car? It’s easy to do, and usually results in a lot of ‘fireworks’.
If your ammeter is not burnt internally and has low resistance, watch the needle when you apply some current through it. if the needle moves, you avoided damage to the meter.
I believe the wiring diagram in the owners manual lists the wire size. Some heavy wire like a #10 and #12 is used. most is #14 and #16, Wire gauge is inverse: larger number is a smaller wire. There is no #18 as I recall.
Hope this helps. Greg Long
Oh, if you DO decide to use a 12v battery to assist starting your car, make the connection of the jumper cables on the battery posts. Then engage the starter, and THEN connect the cables to the 12v battery. I typically will put a 12v battery on the running board next to the open driver’s door, make the connections on the car battery, make one connection on the 12v battery, double, then triple check polarity. Then hit the floor-starter button, and then touch the last cable clamp to the 12v battery with my left hand.
It is not a good idea to leave a 12v battery hooked to a 6v battery, it is a LOT of current and too much voltage and can cause the 6v battery to gas-off or even explode… you do NOT want a shower of battery acid on you or your car.. But when there is a load on the 6v battery and you temporarily hook a 12v battery via a jumper cable to the battery, the 6v battery is safe from my experiences..
I was using a 12V booster to assist starting. I hooked it up directly to the battery under the floor; positive to positive and negative to negative. The negative battery cable runs directly to the starter, the ammeter cable and battery cable are attached to the same post. Maybe the 12V booster I used had too many amps?
Thanks for your help,
All the current to supply everything except the starter itself runs through the ammeter. So if you have a short anywhere else after the ammeter, then the ammeter and the two wires in and out of the ammeter are also electrically shorted. So for example, if the supply current to the brake switch or reverse light switch was shorted to ground, the ammeter is also shorted to ground..
The ‘hot’ items, those not switched somewhere are the reverse/stop lights, dome light and the horn. All other circuits have some sort of switch before the circuit is ‘hot’.
I’d just explore each circuit one by one until you find a short or determine that the circuit is ok.