Help with Lucas smoke!

[Gordon_Dedrick]

One small connecter...one big disaster. I need help with this one. Took the 59 TR3A out for a short run and noticed the discharge light was on. After inspection I found a disconnect on a wire to spade connector on the alternator. (The car has been converted to neg ground and an alternator). Put a new spade connector on and re connected the battery. Lots of Lucas smoke coming from the alternator area! By the time I could get the batt cable off the wire was toasty and it looks like the yellow wire at the voltage reg was hot too.
The ammeter is pegged out on the positive side, and I have no power on anything other than 12v at the battery. Car is completely dead electrically.
I am guessing that the new spade shorted out with the one beside it? I think I have a GM alternator. Hope you can tell from the photos.
How do I start to trouble shoot this one? I was getting the car ready for a show this week end and I am just sick.
Fuses are ok. Wiring behind the dash looks not cooked at first glance.
Gordon

 

[TR3driver]

From looking at your photo, I'd guess the terminal shorted to the alternator housing. There is very little clearance there, a really bad place to leave the terminal bare. In fact, if it were me, I'd want to source the connector that is supposed to go there (should be readily available as a repair part at your FLAPS).
https://www.americanclassic.com/Google_Base_HTML_Pages/PLG-114-1974.htm

Shorting the two terminals together wouldn't cause that kind of damage (although it would eventually run the battery down).

I'm not sure where the problem would be, but it shouldn't be too hard to find. Get out your test light or voltmeter, and connect one side to a good ground. Touch the probe to the battery hot terminal (to be sure it's still got a charge in it) and then start working your way along the circuit to the rest of the car. Next stop would be the post on the solenoid, then terminal 'A' on the old control box.

I'm guessing you'll find power on the solenoid, not on 'A'; which means the problem is in the ammeter or in the two wires leading to it (brown from the solenoid, brown/white from the control box). So your next step is to get access to the ammeter connections (which is usually easiest for me by undoing the clamp and popping it out of the dash, being VERY careful not to let the bare parts of the wires touch the metal dash). Again check with your test light or voltmeter. Power on both terminals means the brown/white wire is bad; power on neither terminal means the brown wire is bad. Power on one but not the other means the ammeter is bad.

If the ammeter is the problem, you can get by temporarily by just connecting the two wires together. Be sure it's a good sound connection, and well insulated so no possibility of shorting to anything.

When you do hook the ammeter back up, might as well reverse the wires ... it should have been pegged on the discharge side :laugh:

 

[startech47]

Before you remove the amp meter disconnect your battery until you have the amp meter out of the dash and safely supported. You do not need more smoke at this point.

 

[Guest]

I think Mr. Lucas is getting a bad rap on this one. CAUTION!!!! Combining Lucas electrics and other non approved parts can result in serious injury or worse. Many a good karaoke singing voice has been ruined by inhaling the dreaded Lucas smoke,but the deadly GM-Lucas combination {know as GMOKE}has rendered many to a future involoving an iron lung.The word Mustard Gas ring a bell?Procede with caution.Using butt connectors and 99 cent electrical tape will only multiply the danger. Just remember the famous actual quote by Mr. Lucas. "A proper gentleman doesnt motor about after dark". Kinda puts it in the proper perspective.Doesnt it?

 

[jsfbond]

Its ironic that testing on modern day cars involves using a smoke generator to check the system............ LBC's, just slightly ahead of their time.

 

[Gordon_Dedrick]

Randall
Happy ending! Your simple direction got me on the right track and diagnosed a bad ammeter in about 10 minutes!!!
I found the part you recommended and have the wires soldered together with shrink tube covering the repair.
THANK-YOU THANK-YOU THANK-YOU...........
I, along with EVERYONE else on this forum that you spend so much time helping owe you a huge debt of gratitude. We are all VERY lucky to have someone with your expertise level and willingness to make involved things seem so simple.
With visions of new wiring harness's, new parts galore, and lots of $$$, you got me back on the road for the show this weekend for $2.99 @ my local FLAPS.
YOU ARE AWESOME!!! Thanks again
Respectfully
Gordon Dedrick