So...the battery was dead on the Valiant. Dead. Dead. Dead. I tried some tips to fix the circuitry on the HEI conversion and I was convinced all was well. I wanted to test the car before I went out to buy a new battery, so I pulled my wife's Camry around to do a jump start.

I popped the hood and...long story short, both cables were black. The battery terminals covered the indicators on the battery completely. I followed the leads. Determined which one was ground and connected.

Fun fact you probably already know: Toyotas are positive ground.

As soon as I saw the smoke I yanked the cables, but I'm pretty sure smoke means it's too late. The wiring harness on the firewall has melted positive and ground leads on it, but the rest of it looks OK.



The inside of the Valiant was full of smoke too. Looks like it was just from the other side of the bulkhead though. Note the thick red and black wires.



I reversed the jumper cables and the Valiant started and ran until 45 seconds after the cables were disconnected, so I don't think all is lost.

Still...I think I'm going to leave this kind of stuff to the professionals from now on. At least I tried and have the good sense to know when to quit.

What do you think? Will I need to replace the whole wiring harness, or is it possible some of it might be salvageable? Looks like Dago Red still has a 64 Dart wiring harness for sale. I'd just like to know what to say when I tow her to the mechanic. (Besides, "I'm a giant moron.")

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Chuck and the Flying Valiant

Um...naw, they ain't. They're negative-ground, same as your Valiant. There haven't been any positive-ground vehicles made in decades. But even if the Toyota were positive-ground, it wouldn't matter; you connect positive to positive and negative to negative no matter which pole is grounded in either car. I think you misidentified the positive and negative on one car or the other, or possibly lost track of which jumper cable was which.
Probably toasted the diodes in the alternator.
I think there is definitely life after an event like this. Start reading about halfway down in this post.
It will probably be easiest and most satisfactory to go ahead and swap in a complete good wiring harness. You may want to opt for a new one from Evans Wiring, who can also customise the harness, as for example with provisions for the '70+ Mopar electronic voltage regulator and electronic ignition, etc., to undo previous hacks of unknown quality (such as the Ford voltage regulator...which, with all due respect to your buddy, there was no good reason to install).

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

*sigh* I was hoping they were. That makes me feel even more dumb for thinking I had carefully checked. (Turns out the only way to really carefully check is to take one of the leads completely off the battery and look under.) Either way, it was a rookie mistake and I'm properly shamed.
I was hoping it was just because the battery was too dead to hold a charge, but I'm sure you're right. Ah well.
Not my buddy and no respect needed. He should have never put that thing in my car.

Thanks for the encouraging anecdote, Dan. Glad to know other people have had to deal with something similar. I'll look into Evans. Hopefully Dago Red's harness works out, but I'll see what they can do. I really need to keep costs down because I'm going back to college and it ain't cheap.

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Chuck and the Flying Valiant

You sure... we're barely 1 month into the year...... 11 months left for someone to "top" you.

I dunno. Getting the + and - on a battery screwed up seems pretty stupid...

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Chuck and the Flying Valiant

I would say ,you probably hooked it up the same side as on your car ,and the toyotas was the opposite. hopefully not an expensive lesson .
Everybody has done something, they should have known better, but the next time I am sure you will make sure. Good luck

Dave

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81 Dodge D150
It looked easier in the book .

Thanks, Dave. I like your signature. I was just saying that tonight as I looked over the wiring schematic in my service manual.

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Chuck and the Flying Valiant

Hey, don't beat yourself up too badly. We've all made mistakes. At the very least, you probably learned an important lesson for next time.

Roger

But something we've pretty much all done before! I did it while trying to be kind to a complete stranger. My buddy did it to my Dart just a couple weeks back. I got off lucky both times...

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Thanks, guys. It's nice to hear I'm not the only one that's slipped up with the battery cables. I think the shock has worn off after a night's sleep. I'll get it fixed and she'll be back on the road in no time.

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Chuck and the Flying Valiant

In your case (a 100% dead battery) it wouldn't have helped, but long ago I instilled the strong habit of a fast "wipe" of all second connections before securing. It's spared me much grief and some coin over the years.

My old high school auto shop teacher called it the "Zap" test.
Thank you Mr. Myers.

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Sex, drags, and rock & roll.
Dick, 225% crazy.
Hobby (cars, that is) Photos link

Yeah, I figured the battery was a lost cause. I was more interested in seeing if my circuit modifications had worked. Next time I'll just bite the bullet and get a new battery.

That's a good test. I'll have to try Mr. Meyers' method.

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Chuck and the Flying Valiant

You should make the last connection to the block. That will helpreduce the chance of frying diodes in the recipient car.

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Dave

1977 d-200 crew cab ex-army pickup wants it's /6 back
1962 Valiant 2 door, 170, three on the tree
1972 d-100 parts truck
80 volare wagon now a parts car

No, nuttyprof, it won't. If the booster cables are hooked up backwards, the diodes will fry immediately whether the final connection is made to the block or to the battery.

The (only) reason for making the final connection to a non-battery ground point on the dead car is to keep the sparks away from the battery, thus reducing the chance of an explosion.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

No one has mentioned that the positive + battery terminal post is always larger diameter than the negative - terminal post. (except side terminal batteries)