Either a dead short or ground wire issue

Tiny
FRANK H.
  • MEMBER
  • 2003 CHEVROLET SUBURBAN
  • 5.3L
  • V8
  • 4WD
  • 211,000 MILES
Four wheel drive for one. I found my SUV was in 4 wheel low when I started it up. And bought a new switch assembly and also replaced a 50 amp blown fuse. Which seemed to work. But when I go from 4 wheel low to either 4 high or 2 wheel I get a slight clunk. It only happens when it's in neutral. Doesn't do it in any other gear. Is this just common sound when shifting to 4 wheel low or do I have a problem? Also I either have a dead short or a loose ground wire. When I checked my new battery with my multi-meter while the engine was running the positive post sparked slightly and melted the positive wire on my multi-meter. I don't know whether the multi-meter was broken or I have a dead short somewhere.
Wednesday, May 20th, 2020 AT 7:58 AM

8 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Good morning,

Did the positive cable spark while connected? Did you verify the connection?

https://www.2carpros.com/articles/how-to-check-wiring

Melted the positive of the meter?

Did you remove the cable while running?

Yes, the noise is normal when the motor on the transfer case moves.

I attached a wire diagram. There is no 50 amp fuse. Can you tell me the fuse number that had 50 amps that failed?

Roy
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Wednesday, May 20th, 2020 AT 9:30 AM
Tiny
FRANK H.
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There is 2 50 amp fuses under the hood fuse box towards the middle. There's 1 50 then a 40 a 50 and a 30. And no I don't believe it sparked when I installed the battery. But it did melt the positive wire to my multi-meter.
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Wednesday, May 20th, 2020 AT 10:04 AM
Tiny
FRANK H.
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It is mbec 1 50 amp.
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Wednesday, May 20th, 2020 AT 10:05 AM
Tiny
ASEMASTER6371
  • MECHANIC
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Okay, I am concerned about the meter end.

What were you doing when the red lead from the meter melted?

That fuse is the feed for the relay block.

I attached a diagram for you.

Roy
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Wednesday, May 20th, 2020 AT 10:10 AM
Tiny
FRANK H.
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I was just checking the current to the battery. I hooked up the negative side first and then touched the positive side. Also it was running at the time.
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Wednesday, May 20th, 2020 AT 4:43 PM
Tiny
ASEMASTER6371
  • MECHANIC
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The negative cable is always the first one off and the last on installed. That arc from the positive could easily damage the module from the voltage spike.

Roy
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Wednesday, May 20th, 2020 AT 4:56 PM
Tiny
FRANK H.
  • MEMBER
  • 5 POSTS
Thanks. I'm also in the process of checking all my major ground wires.
I've been having a few electrical problems and I suspect it has to do with my ground wires. My left front driver side door assembly is broken and also when I tried to get the seat switch removed, low and behold it started working again. I need to find out where all the main grounds are so I can clean them up and reattach them. By the way. My 03 5.3 vortec engine is fuel injected. Does that make it an lmg? Or what would it be in that year?
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Wednesday, May 20th, 2020 AT 6:28 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
I attached a list and locations of the grounds for you to check.

They do not show a diagram but if you need a specific location, reach out to me and I will see if I can get a picture for you.

Roy
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Thursday, May 21st, 2020 AT 4:11 AM

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