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5.3 OBD2 Wiring

Tall Boy

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Joined
Aug 1, 2022
Member Number
5412
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5
Hey fellas. First post here... The motor on my buggy is running like shit. I have been trying to figure it out for a couple month now. I bought an OBD2 reader to see if it has any codes. The OBD2 plug isnt getting any power.

I hear its common for a fuse to go out to cause it not to get power so Ive torn the dash/engine bay apart looking for a fuse box. All the fuses that i can find are fine. there are only a couple in line fuses. No fuse pannel anywhere. Only other fuses are the press to reset that are in the dash.

So im wanting to try to hotwire it from the computer to the OBD2 plug. Ive searched all over and cant figure out which wire goes out of the computer. Its a 5,3 out of a 07 Silverado.

Can anyone help?
 

Twankie

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284
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07 classic or 07 newer body style? Gmt800 or gmt900
 

Bebop

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May 26, 2020
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That's for a GMT800, Gen3 5.3.

The Gen4 5.3 has a different ECU / wiring.
 

Leadfoot21

Red Skull Member
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Mar 27, 2021
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3723
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287
^ what he said you need to check the cigarette lighter or Aux power fuse
 

Tall Boy

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Aug 1, 2022
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5412
Messages
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It turns out that it has power and it is connected to the computer. What are the chances someone tried to tune it in the past blocks the OBD2 out? Is that possible?
 

Twankie

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Make sure pin 2 is going to the pcm
pins 4 and 5 are grounded
And pin 16 gets 12v-+ in the obdII port
 

Tall Boy

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5412
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That is correct. They are all in the right spots. It gets power. It just won’t connect to the computer.
 

Chief Rocka

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155
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Did you try the reader on another vehicle? If yes and it works, issue could be with ECM... causing it to run like shit.

Continuity test btwn ECM connector and OBD port?

What changed between it running well and then not? Welding with batt connected?
 
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