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10-30-2020, 05:45 PM
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#1 |
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Registered User
Join Date: Jan 2019
Location: Bonner Springs, KS
Posts: 56
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Ground the PCM
Went for my first start today with 5.3 swap homemade harness. Dead with no fuel pump kick on. I imagined the worst, did the harness myself with lt1swap instructions. Read on another sight to ground the pcm case. It fired right up
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10-30-2020, 09:37 PM
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#2 |
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60-66 Nut
  Join Date: Mar 2007
Location: Coeur d'Alene, Idaho
Posts: 23,252
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Re: Ground the PCM
Thanks for the insight.
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10-30-2020, 10:23 PM
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#3 |
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Senior Member
Join Date: May 2009
Location: Fort Worth, TX
Posts: 6,370
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Re: Ground the PCM
The PCM body doesn't need to be grounded......If it did, You're missing ground connection somewhere.
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10-31-2020, 04:18 PM
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#4 |
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Registered User
Join Date: Jun 2015
Location: Carlos MN
Posts: 2,131
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Re: Ground the PCM
I've never grounded the case of the PCM on my LS swaps. But I've never built a harness myself. Always purchased the PCM and harness from the same supplier.
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11-01-2020, 07:35 PM
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#5 |
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Registered User
Join Date: Jan 2019
Location: Bonner Springs, KS
Posts: 56
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Re: Ground the PCM
Now that I think of it, there were a few stray ground wires not accounted for, but grounding the case fixed it
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11-03-2020, 12:02 AM
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#6 | |
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BMW & ASE Master Certified
Join Date: Feb 2004
Location: Houston, Texas
Posts: 1,266
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Re: Ground the PCM
Quote:
if that's the case, your going to be creating problems thats going to be hard to trouble shoot over the web....
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11-01-2020, 10:25 PM
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#7 |
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Post Whore
 
Join Date: May 2015
Location: Alabama
Posts: 14,670
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Re: Ground the PCM
With a LS swap, the more grounds the merrier...
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Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver |
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11-02-2020, 09:31 PM
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#8 |
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Senior Member
 
Join Date: Sep 2005
Location: Lewisville, Nc
Posts: 10,237
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Re: Ground the PCM
I had to do the same thing on my swap about 300 miles into swap I had lot of run issuses turns out I never bolted the grounds to back of the head and they where touching hit a bump lost ground I felt like an idiot but never went back and ungrounded the pcm
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11-02-2020, 10:36 PM
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#9 |
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Registered User
Join Date: Jun 2015
Location: Carlos MN
Posts: 2,131
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Re: Ground the PCM
As said above Ls swaps love good clean grounds. Main ground cable from the battery I run the 00 gauge cable directly to the engine block. Then on each side of the engine block back to the frame. Similar size cable. I try to hide them. If you have any paint on the block make sure you sand down to good metal. Star lock washers help bite into the head bolt holes.
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