What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

LS Swap, Battery Overheating, help!

robster495

robster495

1/2 ton status
 Premium
Joined
May 14, 2014
Posts
104
Reaction score
45
Location
Baltimore
Hey guys, I have an '03 LQ9 in my '91 Suburban.

I had it running for a minute or two, and the battery was waaaay hot and smoked a little. It must be a wiring issue, so I'll tell you what I have.

Battery (+) to alternator post, alternator post to powerblock, powerblock to starter, starter back to battery (+)

Batter (-) grounded to body, block, and frame.

I think I need to lose the battery (+) to starter, or lose the starter to powerblock.

Let me know what you all think!!
Thanks
 
robster495 said:
Hey guys, I have an '03 LQ9 in my '91 Suburban.

I had it running for a minute or two, and the battery was waaaay hot and smoked a little. It must be a wiring issue, so I'll tell you what I have.

Battery (+) to alternator post, alternator post to powerblock, powerblock to starter, starter back to battery (+)

Batter (-) grounded to body, block, and frame.

I think I need to lose the battery (+) to starter, or lose the starter to powerblock.

Let me know what you all think!!
Thanks
Click to expand...


A battery getting hot is either a direct short, or overcharging alternator. Measure the voltage while the truck is running. If it’s anything over 14v that’s your issue. The battery could have a dead cell as well.
 
robster495 said:
Hey guys, I have an '03 LQ9 in my '91 Suburban.

I had it running for a minute or two, and the battery was waaaay hot and smoked a little. It must be a wiring issue, so I'll tell you what I have.

Battery (+) to alternator post, alternator post to powerblock, powerblock to starter, starter back to battery (+)

Batter (-) grounded to body, block, and frame.

I think I need to lose the battery (+) to starter, or lose the starter to powerblock.

Let me know what you all think!!
Thanks
Click to expand...

Are you saying you have the positive battery cable connected directly to your alternator?
 
My truck is wired up in a more traditional way. The positive battery cable goes to the starter solenoid battery stud. A hot lead also goes from the alternator to the battery stud on the starter solenoid. I also hooked up a direct positive lead from the alternator hot to the battery positive post.
 
1-ton said:
My truck is wired up in a more traditional way. The positive battery cable goes to the starter solenoid battery stud. A hot lead also goes from the alternator to the battery stud on the starter solenoid. I also hooked up a direct positive lead from the alternator hot to the battery positive post.
Click to expand...

I essentially have this same set up, too. On our square bodies there is that small power junction on the firewall, which is included in my wiring
 
if i recall from years ago some of the ls alts are computer controled in a way .

make sure your not cooking the bat and or a alt not working the way you need it .
 
I want to lean towards my wiring. I took the alternator from a 5.3 in my wrangler, and I know it's good.

In my wiring harness I have 3 wires going to the alternator plug, but I've usually used a single wire set up. Is that what I should look at? It seems my hot leads are what you all recommend
 
sweetk30 said:
if i recall from years ago some of the ls alts are computer controled in a way .

make sure your not cooking the bat and or a alt not working the way you need it .
Click to expand...

I believe in my OBD-I/TBI engine the ECM can control the internal voltage regulator in the alternator. From what I have been told the ECM can give the voltage regulator the signal to increase voltage while at a low idle instead on relying on the engine RPM's to dictate what and how much the voltage regulator will put out.
 
Last edited:
Make sure the positive battery cable terminal end is not touching anything that could ground it at the starter solenoid. If the positive battery cable terminal end gets spun around on the starter solenoid battery stud it could touch something that will ground it.
 
All the positive connections are clean and isolated from potential ground like that!

Is the battery a potential issue? It was completely dead (for days and days before that), and I charged it overnight. Threw it straight into the truck after that
 
robster495 said:
All the positive connections are clean and isolated from potential ground like that!

Is the battery a potential issue? It was completely dead (for days and days before that), and I charged it overnight. Threw it straight into the truck after that
Click to expand...

I have a an old junk battery sitting around right know that has a negative terminal turned completely black from heat build up, yet will still hold a charge for the most part.
 
Last edited:
1-ton said:
I have a an old junk battery sitting around right know that has a negative terminal turned completely black from heat build up, yet will still hold a charge for the most part.
Click to expand...

Okay so the battery isnt the issue then?
Another thing I can think of is this: the wiring harness is modified from a Yukon that had the small 2pin alternator plug, but my tuner changed it to the flat4pin alternator plug to match up to an alternator I had. Could that be an issue?
 
I know that those alternators have remote sense for the voltage regulator. I do not know if it is coming from the ECM, I thought that it read voltage at the battery. So you have to find out which wire of the small wires needs to control the voltage.

Was the battery hot when you put it in? Maybe it was hot AND it's getting overcharged.

You may also have a battery problem, you will have to test it to see. Check the voltage in it with nothing hooked to it, let it sit overnight and check it again. It should still be above 12.3 volts typically.
 
robster495 said:
Okay so the battery isnt the issue then?
Another thing I can think of is this: the wiring harness is modified from a Yukon that had the small 2pin alternator plug, but my tuner changed it to the flat4pin alternator plug to match up to an alternator I had. Could that be an issue?
Click to expand...

No, I meant your battery could very well be the issue. The battery I mentioned although it works I do not trust it, which is why it is just a junk core to me.
 
robster495 said:
Okay so the battery isnt the issue then?
Another thing I can think of is this: the wiring harness is modified from a Yukon that had the small 2pin alternator plug, but my tuner changed it to the flat4pin alternator plug to match up to an alternator I had. Could that be an issue?
Click to expand...
The only way to eliminate the battery as the culprit is to load test it.
A bad battery could do that
Actually leaving the battery overnight will tell you because it will stay hot and die overnight
 
Okay, after work today I will get back in there and see what the battery is like. I left it unplugged.

Question, my positive wiring is still correct though, right? Battery (+) to starter and alternator? Alternator to power junction, and power junction to starter?
 
robster495 said:
Question, my positive wiring is still correct though, right? Battery (+) to starter and alternator? Alternator to power junction, and power junction to starter?
Click to expand...

As long as you've got the proper gauge for the load each wire will be carrying, it doesn't really matter. Sounds to me like overkill if anything, but nothing wrong with the routing. Can't go wrong with positive to positive.

Commonly folks that are "improving" the charging circuit run the alternator output to the battery, battery straight to starter, and one wire to the junction block.
 
You must log in or register to reply here.

Latest Posts

Top Bottom