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02-06-2019, 10:27 PM | #1 | |
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Re: OBD gremlins ... need assistance please
Quote:
Let me know
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HSRACER Slammed 53 5 window Blown/Bagged 54 Pickup Patinaed 67 LS stepside Supercharged 67 Nova Bagged 69 Suburban Turbo'ed 5.3 LS |
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02-08-2019, 02:18 PM | #2 |
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Join Date: Feb 2004
Location: Houston, Texas
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Re: OBD gremlins ... need assistance please
PM sent
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1987 Silverado - L83 5.3 w/ 6L80e ,A/C,P/W,P/L,TILT, HID projectors, Wilwood C-10 Pro Spindles w/ 2018 silverado front brakes & C-5 Corvette Rear Disc Brakes 1999 BMW 528i - 5.7 LS1 w/ 4l60e, Ford 8.8 IRS w31 spline posi & FX-r projector retrofit New project: 2006 BMW x5 6cyl AWD to L83 6l80e 4wd to 2WD / RWD A poor man buy's it twice finally got my domain name back, 87chevy.com.... site rework in progress |
02-10-2019, 12:00 AM | #3 |
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Location: Katy TX
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Re: OBD gremlins ... need assistance please
So today’s results were a mixed bag. We did all the things we knew to do and had zero results with this silly obd connection.
The main reasons I needed the obd was to turn the fans control on for my new electric fans and that was when I figured out I could no longer communicate with it. A couple of days ago I got the computer out of the truck and took it to my tuner. We set the fans at the on/off temperatures we wanted and verified that there were no communication problems with his bench connection. The fans now work as they should when the truck gets up to temperature and that is the positive part of the mixed bag of results. The negative is we still can’t get the obd to communicate with the darn computer. We put all new pins in the Obd and ran new dedicated wires with no splices in them at all. The obd constant power was directly hooked to the battery, the grounds were directly attached to the block, the data line was separate from the harness as were the other three. Basically we moved the connections outside of the harness, ran all new wires, verified grounds and power with no luck on the communication at all. This computer will communicate when it is in other vehicles and I am out of ideas! Anyone have anything else to try??......... As the post title says.... any help is appreciated
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HSRACER Slammed 53 5 window Blown/Bagged 54 Pickup Patinaed 67 LS stepside Supercharged 67 Nova Bagged 69 Suburban Turbo'ed 5.3 LS |
02-10-2019, 06:45 PM | #4 | |
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Re: OBD gremlins ... need assistance please
Quote:
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My '72 short bed build. http://www.ls1tech.com/forums/conver...6-0-4l80e.html 5.3 swap into my RUSTY '71 C10 http://ls1tech.com/forums/conversion...71-c-10-a.html |
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02-10-2019, 12:17 PM | #5 |
meowMEOWmeowMEOW
Join Date: Sep 2009
Location: MKE WI
Posts: 7,128
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Re: OBD gremlins ... need assistance please
I noticed you still said both grounds are going to the block. Did you ever look any more at the "signal ground" instead of putting both straight to block? It looks like you tried everything else.
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'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD
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02-12-2019, 05:37 AM | #6 | |
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Re: OBD gremlins ... need assistance please
Quote:
There was two (and still is a small pink and a small black) wires that were cut and I assume they were for the check engine light. The check engine light works in the Dakota Digital gauges as it comes on when the key is on and goes off when the engine is running. I keep wondering if these have anything to do with the situation but am unsure what to try with them.
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HSRACER Slammed 53 5 window Blown/Bagged 54 Pickup Patinaed 67 LS stepside Supercharged 67 Nova Bagged 69 Suburban Turbo'ed 5.3 LS Last edited by HSRACER; 02-12-2019 at 06:00 AM. |
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02-12-2019, 11:18 AM | #7 | |
meowMEOWmeowMEOW
Join Date: Sep 2009
Location: MKE WI
Posts: 7,128
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Re: OBD gremlins ... need assistance please
Quote:
I don't see any black wires going to MIL control on the schematic that I'm referencing (the schematic on Lt1swap, not the harness legend).
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'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD
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02-12-2019, 11:36 AM | #8 | |
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Re: OBD gremlins ... need assistance please
Quote:
He remembers cutting them and moving the new connections to inside the truck.
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HSRACER Slammed 53 5 window Blown/Bagged 54 Pickup Patinaed 67 LS stepside Supercharged 67 Nova Bagged 69 Suburban Turbo'ed 5.3 LS |
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02-11-2019, 12:05 PM | #9 |
BMW & ASE Master Certified
Join Date: Feb 2004
Location: Houston, Texas
Posts: 1,266
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Re: OBD gremlins ... need assistance please
Yep, positive the obd wiring is spot on. It has to be a wire shifting to something else causing the obd issue. Down side is no way of knowing since there is no way of knowing unless the harness is unwrapped and all the wires spread apart and trying to read again.. that's my last guess .. it's one downside on Ls swaps the wiring is old, then the junk yard fiddles with the wiring, then an installer mods the harness
. All that wiggling around can lead to wiring issues. The fan wire they left us was 1-2 feet away from the pcm... that wire had had an open causing the fans not to work
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1987 Silverado - L83 5.3 w/ 6L80e ,A/C,P/W,P/L,TILT, HID projectors, Wilwood C-10 Pro Spindles w/ 2018 silverado front brakes & C-5 Corvette Rear Disc Brakes 1999 BMW 528i - 5.7 LS1 w/ 4l60e, Ford 8.8 IRS w31 spline posi & FX-r projector retrofit New project: 2006 BMW x5 6cyl AWD to L83 6l80e 4wd to 2WD / RWD A poor man buy's it twice finally got my domain name back, 87chevy.com.... site rework in progress |
02-11-2019, 02:47 PM | #10 |
Senior Member
Join Date: Jun 2015
Location: Atlanta, GA.
Posts: 737
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Re: OBD gremlins ... need assistance please
ok, i'm going out on a limb here but might be worth trying.
Ask the tuner HOW his OBD connector on this bench set is wired in. Where does HE pull power from and where does it go to on the PCM & OBD connector? Where does HE pull grounds from and send to? In other words, duplicate the last known correct functioning while in the truck. If this can NOT be duplicated while installed in the truck, my thinking here is that maybe, just maybe, there is another circuit somewhere in the harness that is PREVENTING the PCM from communicating. Like one PINK wire that was omitted in the harness and that one slot on the PCM plugs may enable communication. Maybe one Ground on the Bench set up that was omitted and PREVENTS communication? Again, I'm going out on the limb but it sounds like you have narrowed it down to a bad harness. Look for anything that is not present in the harness but IS in the bench set up. (power, ground, communication wise) If anything, it may shed some light on an issue. Another thing to consider is the addition of the A/C and other items right before this issue started. Maybe disconnect them to see if there was any affect with communications. If all this fails...its time to cut the harness open and do it the old fashioned way, one wire at a time. Start with LT1Swap wiring guide and go wire by wire.
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Jay Gesner Atlanta, GA 1985 C10 Long Bed 4X2 LS 5.3, 4L60E Father/Daughter Project Last edited by Wgesnerjr; 02-11-2019 at 02:52 PM. |
02-12-2019, 05:51 AM | #11 | |
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Join Date: Sep 2007
Location: Katy TX
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Re: OBD gremlins ... need assistance please
Quote:
I can try and see where these wires go the next time I have the computer unhooked and see if I can get a pin location. My other friend who helped me Saturday that moved all the new wiring and installed the pins said basically to start pulling the harness apart as well. When we tried the fans they didn’t work initially, and we found the fan control wire from the computer open. After running a dedicated new wire from the computer they worked flawlessly. So now everything is working on the truck...... gauges, fan control, speedometer, great tune, transmission shift points etc. I am mentally exhausted on the obd issue and just want to enjoy the truck but I know in the back of my mind that it isn’t right. If I ever have any problems on the road I will be stranded as we wil not be able to diagnose anything until I can get the truck home and remove the computer and get it to my buddy for a bench tune analysis. This truck has turned into my daily driver as I enjoy it so much. I have others to use but keep going back to this one. I am working in Chicago this week and will take a break from all this fun and may attack it upon my return or drive it a month or so and regroup mentally. Btw, I drove it to the airport and it will be the first thing I drive to get home
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HSRACER Slammed 53 5 window Blown/Bagged 54 Pickup Patinaed 67 LS stepside Supercharged 67 Nova Bagged 69 Suburban Turbo'ed 5.3 LS |
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02-12-2019, 12:21 PM | #12 | |||
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Location: Independence Mo
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Re: OBD gremlins ... need assistance please
Quote:
Quote:
Quote:
Also, you know taking the computer out to scan it wont work, since when you unhook it, it will loose all its stored codes. My other question for you is, did you just leave this truck at the airport??? That would make me a nervous wreck!
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My '72 short bed build. http://www.ls1tech.com/forums/conver...6-0-4l80e.html 5.3 swap into my RUSTY '71 C10 http://ls1tech.com/forums/conversion...71-c-10-a.html |
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02-12-2019, 02:08 PM | #13 | |
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Join Date: Sep 2007
Location: Katy TX
Posts: 1,268
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Re: OBD gremlins ... need assistance please
Quote:
We ran all new dedicated wires to the obd inside the engine compartment and when that didn’t work I elected not to run them into the cab. The harness is thought to have a possible short or grounding issue causing the obd not to work but that is just speculation since we haven’t gutted the harness. I didn’t know you loose all the info when removing a computer. Thanks for letting me know. I am just now starting my LS Education! So the cut pink wire is still just capped in the harness as is the ground. I am not sure where my friend picked up the power and ground for the light in the Dakota Digital gauges. Not sure if it will even set a light if a code shows up. Heck yes I left it at the airport. Who would want an old patinaed 67 when they can pick anything to steal. Also it is fully insured.
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HSRACER Slammed 53 5 window Blown/Bagged 54 Pickup Patinaed 67 LS stepside Supercharged 67 Nova Bagged 69 Suburban Turbo'ed 5.3 LS Last edited by HSRACER; 02-12-2019 at 05:09 PM. |
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