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'29 DA short?...or multiple shorts?


Bob Zetnick
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I think I may have a short.... or multiple shorts on my '29 DA. 3 people have worked on my wiring incl. myself, but main harness is from Rhode Island Wiring. I have a new battery and coil as of last year and starter was rebuilt in 2009, but I've only been driving car since 2018. Wiring is all new, I've checked most connections and fuses (plural as I've added a few accessories) are all okay. I do have a disconnect switch that I turn on everytime I get in car.

First, dome light and switch worked before upholstery installed, but now only works when directly connected to battery. Since I got upholstery in, its never worked again....thought maybe the guy knocked the ground loose or put an upholstery nail through wire up windshield post.

Second, 6 weeks ago lights and horn wouldn't work...you'd think something w/ CLUM switch, but an added spotlight w/ no connection to CLUM wouldn't work either....again, all fuses okay.....next day everything worked fine.

Yesterday, lights and horn wouldn't work again....when I started the car, then everything went on....I started it again and all was fine.....cleaned her up a little and went to start for a drive and nothing. All lights and horn worked, but starter didn't make even a sound...tried again this a.m. and again, nothing on starter.

Everything is new or rebuilt. I'm not sure if all this is related or separate. Hate to remove upholstery for dome light wiring unless I know it's the culprit, so thought I'd ask for any advice first.

Thanks in advance!

 

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I would start by checking all the earth connections. Pull them off and clean back to bare clean metal. Make sure there is no paint under the connections. If your using original old switches the contacts could be either worn or dirty so they may need to come apart and be cleaned. 
good luck, finding wiring faults can be a pain especially when they are intermittent. 

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1 hour ago, Mattml430 said:

I would start by checking all the earth connections. Pull them off and clean back to bare clean metal. Make sure there is no paint under the connections. If your using original old switches the contacts could be either worn or dirty so they may need to come apart and be cleaned. 
good luck, finding wiring faults can be a pain especially when they are intermittent. 

Yep, battery and starter switch looks good....I'll check some others.......still don't know why it seems intermittent.

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Kevin BC here

Do you have a earth strap between the motor and the chassis, my Dodge 8,s both have a strap from the engine rear mount/bel housing to the chassis, by passing the rear engine mount to give the motor a good earth, it is not relying on the front solid mount of the motor which could  have paint , or rust preventing a good earth though the front mount, which is the only contact of the motor  to the chassis.

 

regards Kevin

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15 hours ago, Kevin bc said:

Kevin BC here

Do you have a earth strap between the motor and the chassis, my Dodge 8,s both have a strap from the engine rear mount/bel housing to the chassis, by passing the rear engine mount to give the motor a good earth, it is not relying on the front solid mount of the motor which could  have paint , or rust preventing a good earth though the front mount, which is the only contact of the motor  to the chassis.

 

regards Kevin

Thanks, I will check more connections this weekend. My ground cable runs from battery to disconnect switch on firewall, then runs from that switch to a rear starter bolt that mounts starter to rear engine frame member. ...major connections look good, but will check again. That said, car was working fine for 2 years until last week and wondered if it had something to do with lighting problem....that may be a different issue.

 

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If your engine is mounted on rubber you would be wise to add a strap from that starter bolt to the body. (I assume your lights are mounted on the body)

You could even put a second wire from the disconnect post to its mounting screw.

I have seen more than one case where the body isn't a well grounded to the path to the battery.

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51 minutes ago, JACK M said:

If your engine is mounted on rubber you would be wise to add a strap from that starter bolt to the body. (I assume your lights are mounted on the body)

You could even put a second wire from the disconnect post to its mounting screw.

I have seen more than one case where the body isn't a well grounded to the path to the battery.

Thanks, I'll try that. Does a second ground need to as heavy a wire as the main ground?

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Not really as you wont be cranking thru it.

I see some cars come with a smaller one of those web looking straps that run from the back of the block to the firewall.

I guess you could experiment with some jumper cables in your troubleshooting procedure.

 

I had a guy once come to my shop complaining that his gas pedal was sparking when he turned on his headlights.

It was an older pickup that used a rod thru the floor under the foot feed and the rod was scraping against the floorboard. The headlights were looking for a ground back to the battery.

I suspect that he was getting sparks there when it was light out as well.

 

Some wise old guy once told me that "90 % of all electrical problems are groundless".

Good luck.

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55 minutes ago, JACK M said:

Not really as you wont be cranking thru it.

I see some cars come with a smaller one of those web looking straps that run from the back of the block to the firewall.

I guess you could experiment with some jumper cables in your troubleshooting procedure.

 

I had a guy once come to my shop complaining that his gas pedal was sparking when he turned on his headlights.

It was an older pickup that used a rod thru the floor under the foot feed and the rod was scraping against the floorboard. The headlights were looking for a ground back to the battery.

I suspect that he was getting sparks there when it was light out as well.

 

Some wise old guy once told me that "90 % of all electrical problems are groundless".

Good luck.

Thanks Jack! I remember you using that quote on another one of my electrical problems! :)  Your headlight story may also be my intermittent lighting problem. When I got my car I had the "web strap" ground going from battery to frame....just wanted a cut-off switch this time. When I got my car running again in 2014 a mechanic and I were working on it and the starter would shut off and get warm, so he grounded the starter to the transmission and all was fine......the guys doing the rest of my wiring took this ground off.....I've run the car  many times since I got it on the road in 2018 without problems, but I'm going to try your grounding idea. Thanks!

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  • 2 weeks later...

So, I got an extra cable and have been using it to test grounds for the starter....I also used a test light to to check circuits and haven't found a problem yet. I looked at a Model A video regarding starter "hang-up" where the starter gear can jam into the flywheel ring gear. I loosened the starter enough and thought that I could take it off and check it. Not being a mechanic or electrician I thought I'd ask a stupid question....if I take the starter off to check it I know the hot wire will go to the contact, but do I have to ground the starter case or is the grounded battery enough of a ground?....does that make sense? I just didn't know if I needed more of a ground from battery to starter w/ battery jump cables involved. Thanks!

 

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2 hours ago, Bob Zetnick said:

So, I got an extra cable and have been using it to test grounds for the starter....I also used a test light to to check circuits and haven't found a problem yet. I looked at a Model A video regarding starter "hang-up" where the starter gear can jam into the flywheel ring gear. I loosened the starter enough and thought that I could take it off and check it. Not being a mechanic or electrician I thought I'd ask a stupid question....if I take the starter off to check it I know the hot wire will go to the contact, but do I have to ground the starter case or is the grounded battery enough of a ground?....does that make sense? I just didn't know if I needed more of a ground from battery to starter w/ battery jump cables involved. Thanks!

 

Yes, the starter will need to be grounded.  If your running off the car just bolt a ground cable to one of the mounts.

 

Make sure you have it well secured if testing off the car - the torque reaction can cause it to jump a bit.

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