Vintage Mustang Forums banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Ride of the Month Challenge!

1 - 12 of 12 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
The guy who helps me work on my cars is out of town so I'm trying to figure out what is likely a simple problem. My 66 Mustang battery was dead. When I went to jump it, I noticed that the clamps that connect the ground wire to the battery terminal were loose. When I started to tighten the connection on the negative terminal, sparks were flying. When I jumped it, I could see sparks coming from the battery area. I was jumping it using a battery in a 44 Jeep (the battery was not connected, however, to the jeep.The jeep is 12v.

Could this be a short in the solenoid?
 

·
Premium Member
Joined
·
13,229 Posts
If the key in your Mustang is OFF when the sparks fly then something "unswitched" is creating a heavy draw on the battery. Maybe the solenoid is stuck in the closed position. Trying to start an engine with a weak battery will sometimes do that. Try rapping on the solenoid with the handle of a large screwdriver or a wooden hammer handle. That may pop it loose.
 

·
Premium Member
Joined
·
6,105 Posts
Depends on how well the connections are made. Moving things, twisting a battery cable, corrosion and micro-welding etc will make that connection intermittent.
 

·
Registered
Joined
·
1,404 Posts
If you re-connect a battery when the key is on and the points are closed, you'll get a spark at the battery terminal (not good if you have a battery that isn't a sealed one). You will only get a spark while re-connecting a battery (with key off) if something is shorted directly to ground (or you have an accessory that is powered directly from the battery ie: radio, 4 way flasher switch, etc. If your battery is warm from a fresh re-charge, it might still be venting hydrogen gas when you re-connect it. DANGER! Hydrogen gas is highly explosive.
 

·
Registered
Joined
·
2 Posts
Discussion Starter #9
Wouldn't it always spark since the positive red cable is connected to the battery?
On closer inspection, the "spark" was strong enough to melt the lower portion of the lead battery terminal where you tighten the clamp to connect the negative wire to the battery terminal. I'm having the battery tested today.
 

·
Registered
Joined
·
210 Posts
I had a similar problem because of a short in the 8 gauge wire connecting my in-tank electric fuel pump.to the fuel pump relay under the dash. After removing the interior, the glove box, the ashtray and both kick panels I found that the previous owner had squashed the wire with the seat belt bracket and bolt. Problem solved!
 

Attachments

·
Registered
Joined
·
689 Posts
As mentioned above, if there is a spark when you connect the negative lead while the positive lead is connected, something is turned on or shorted creating a path allowing the current to flow. You have to use a process of elimination to find what is allowing the current flow. You can pull all the fuses and see if it still arcs. If it doesn't, put them back in 1 at a time and see which segment of the circuit is allowing the current flow. Once you find the segment, look in the shop manual to see what that fuse feeds and continue isolating things on that segment until you find whats on or shorted.
 

·
Registered
Joined
·
730 Posts
Were either of the doors open when you were messing with the battery? If so, then the interior lights would be on.
 
1 - 12 of 12 Posts
Top