Start relay smoking after AAW install.

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John Collins

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After 2 years of messing around with my car’s electrical, without success, I finally ponied up and did a full rewire… I ended up installing a new AAW harness and I’m getting a touch of smoke coming from the starter relay. The red power wire from the from the battery post on the starter relay that leads to the battery post on the starter is warm to the touch. I suspect a bad ground, but I don’t know how. Any help would be greatly appreciated.

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This happens only during cranking, correct?

A few questions/ideas:
What type of starter is it, and how old?
Is there paint or corrosion on/under the ground cable's connection to the block/head (not sure which engine you've got)?
Have you checked your negative battery (ground) cable for internal resistance with a multimeter? I've seen new-looking ones that were solid green under the insulation.

My first impression is that it's ground-related, meaning you've got a weak connection there somewhere. To push through the ground problem it's dragging a ton of amperage through the positive side of the relay.
 
That, or you have a dead short between the relay and the starter.
My clutch pushrod once rubbed through my starter wire and it wound up burning up one of my ground wires (to the core support).
Smoke is obviously never normal. Would be a good idea to start tracing things using a multimeter with the battery disconnected.
 
Thank you for your quick response!

LA 360… Later casting.

I don’t know the age or history of the starter, but it looks like it’s original. Firstly, I sanded and cleaned where my grounds are installed. The Negative battery cable is the same one I had before the rewire, but I did not check the resistance after re installing. I’ll go check that now.
 
Sorry… Not during cranking, it always happens. The red wire from the starter relay flexes a little bit when my charger activates…
 
So let's start at the beginning...

You replaced your wiring.

The run from the battery to the starter relay is the heavy red.

The purple runs to the starter solenoid

The yellow comes from the ignition switch

The black goes to the NSS.

When you put the battery cables on the battery the red cable gets hot and smokes.


That is what I am figuring from your post #1.


Is that correct?
 
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Yes sir, that’s correct, except that I can’t tell with certainty which wire the smokes coming from. The smoke is very faint, but definitely coming from the starter relay. The red wire from the starter battery post leading to the starter relay is warm to the touch and so is the positive side of the battery terminal.
 
This is happening with the ignition key on or off? I can safely assume every connection in the car is made--i.e., everything that should be connected, is?

I have to start with the obvious questions; I mean no offense by these. The headlights are off, right? The cigarette lighter isn't stuck pushed in? Both are significant draws that I could see potentially creating a wisp of smoke on a brand-new harness.

On to deeper diagnostics: With the battery disconnected, check resistance from the battery-cable stud on the relay to the relay's case. It must be infinite (open circuit). If you have any number a'tall, replace the relay. You should also have an open circuit between the battery-cable stud and the purple wire when the engine's not cranking. If there's any continuity, try it again with the yellow wire unplugged. If that fixed it, check the yellow wire as described below.

For the next few tests, reconnect the battery only long enough to perform each test, then disconnect it. Don't leave it on the entire time with something generating enough heat to create smoke.

Disconnect the purple wire to remove the starter from the equation. Does the problem persist? It shouldn't if the relay checked out. Next, remove the main power wire from the alternator, wrap it with electrical tape so it can't short and try again. Still hot? The alternator should be OK. I expect it probably is. On a factory harness, a shorted alternator will blow the fusible link like yesterday (ask me how I learned this). With the keys in your pocket, probe the yellow wire. There should be 0.000 volts on it. It should only go hot with the key in "start". If there's stray voltage there, you may have an ignition-switch issue.

There's a big draw somewhere, but it's hard to diagnose long distance. I know nothing of AAW other than they specialize in GM. Is this a direct-fit, 100% OE-style replacement harness--stock colors, connectors, etc.? Did you re-wire the entire car, or just the engine/forward lamp harness? Without factory-style everything, we can neither make educated guesses nor assumptions, and using the FSM is difficult bordering on impossible.
 
Just shooting in the dark.


The red wire might be touching the relay housing here.

Screenshot_20230314-194408.png

ALSO...

I suspect there is quite the spark when you attach the battery cable.

On many / all the A body cars the feed from the alternator attaches to the same post as the red from the battery.

I don't see that on yours. Where does the alternator feed attach?


ANOTHER THOUGHT...

There should not be any connection from the red to any other wire ( except alternator if it was hooked up per OEM)

So if there is a load on the red wire it has to be going through the relay's contacts.

Since you are not sure if the red wire is what is heating enough to create smoke, ( I suspect it is since the battery post is getting hot) the logical thing is that the relay or the wire has a short to ground.

The relay looks a bit bulged (yellow) and old.
I would remove the relay and test it with an ohm meter. I bet you will find that the large post with the red wire is fully or partly shorted to ground.
Possibly from tightening the nut


Screenshot_20230314-195153.png
 
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Did you explain to your relay that smoking is a bad habit?
 
I've been gone all day, obviously got here "late" just some random thoughts

NEVER leave a wire / battery/ power source connected if something is getting warm or smoking. (Maybe I read something into this)

I've "preached" this many many times. When you are making wiring changes, rewiring, or even trouble shooting shorts and heavy unwanted current draw, stick a LAMP in series with battery ground

Use a lamp intelligently--sized to the trouble at hand. a 12V test lamp is nearly useless in this situation. I normally use an old 1157 bulb and socket as you can wire it up to cause it to draw different current You have a bulb there with a low current filament--the tail lamp filament, and a heavier one--the stop/ turn filament

For lightest current, use the two lamp wires for connection, and leave the ground/ shell INSULATED (unconnected) This puts the two filaments in series

Next up, use the shell as one connection, and the tail wire, leaving the stop/ turn wire unconnected

For heavier current, use the shell and the stop/ turn wire, with the tail wire unconnected

And finally, for heaviest current combination, twist the two socket wires together, and use the shell as one connection, and the common of the two wires, lighting both filaments

For heavier yet, use a headlamp

WHAT THESE DO, is you have a lamp in series with battery ground, and this LIMITS system current. You can throw a wrench across any hot connection to ground, and the only thing that will happen, is that your lamp "protector" will light up, limiting current flow.

But if you use a heavy enough lamp, things will somewhat work allowing you to easily troubleshoot. For example, using a series headlamp protector while troubleshooting lighting problems will allow most the lights to at least glow, giving you visual indication
 
Thank you very much y’all! I’m going to trouble shoot after I drop my daughter off at school. I really appreciate all the sound advice!
 
have you called american auto wire and asked them? the tech help is pretty good there.. especially if you get a hold of donnie who designs the kits.
 
Thank you 67Dart. The starter relay was bad. My battery is only at 12.2, so I’m charging the battery and will retest it in a bit with a fully charged battery to see if she starts. Thank you again!
 
After I let the battery charge, it started right up. After 2 years of chasing electrical gremlins, I can finally drive this car. If anyone is reading this and is on the fence about putting in a new harness, I’d highly suggest it. It’s wasted a ton time “learning” and not driving. AAW harnesses are worth the coin, if you lacked the skills like me to Jess around with a universal harness.

Thank you again y’all!
 
John Collins said:
harnesses are worth the coin, if you lacked the skills like me to Jess around with a universal harness
Click to expand...

So the kit you used was an OEM style replacement?

I cringe when I see a post that starts with "I just started installing an EZ... or Painless...
 
It’s an American Autowire Classic Update. It’s a generic 67-75 A Body harness. It has extra configurations intended for different setups. It comes pretty much ready to install with the correct terminals. They’re a ton on pinning to do, but it comes with everything you need. It’s an “updated” harness that has room in the fuse box for multiple modern add ons.

This is my first classic Mopar and after struggling and failing all over the place trying to salvage the original electrical system, this harness made it “easy” for me to get back on the horse. After installing it, I’ve learned a ton and feel comfortable and fairly competent now. It ended taking about 50 hours and 100 beers between me and a buddy to install. I actually had fun doing it.
 
Glad you got it worked out.
 
John Collins said:
It’s an American Autowire Classic Update. It’s a generic 67-75 A Body harness. It has extra configurations intended for different setups. It comes pretty much ready to install with the correct terminals. They’re a ton on pinning to do, but it comes with everything you need. It’s an “updated” harness that has room in the fuse box for multiple modern add ons.

This is my first classic Mopar and after struggling and failing all over the place trying to salvage the original electrical system, this harness made it “easy” for me to get back on the horse. After installing it, I’ve learned a ton and feel comfortable and fairly competent now. It ended taking about 50 hours and 100 beers between me and a buddy to install. I actually had fun doing it.
Click to expand...

their classic update kits are some nice harnesses... some would consider them expensive but you get what you pay for in cases like this.
 
abodyjoe said:
their classic update kits are some nice harnesses... some would consider them expensive but you get what you pay for in cases like this.
Click to expand...
When it comes to your car burning to the ground because of a faulty wiring harness, they become a better deal.
 
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