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Thread: 96,97,98,99 wiring OBS

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  1. #1
    Join Date
    May 2004
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    2,120
    I can't believe all of the differences in the wiring. I think I told someone here that the wiring harnesses are the same but they really aren't after extensive investigating. I'm going to make everything work with the 2002 PCM including the ABS which I'm just about there. I was going to buy a harness but changed my mind so I could see where every wire goes to for myself. I am building a plug and play harness that goes directly from my ABS, Cruise Control, A/C, Tachometer, Temp Sender, Oil Pressure, A/C Controls, Starter, MIL Indicator, Fuel Pump, Ignition feed, EVO Solenoid Bypass, Inlet Air Actuator, Charge Indicator Lamp and VSS which will control the ABS/Cruise Control and Tach. This will pretty much put me back to everything working like it was from the factory and have all the Camaro/Truck Weather Pack Connectors. I'm still having header issues but S&P is working to solve the problem. I do have the drivers side on and it fit's well. This has been an awsome project thanks to you guys input!!


    97 GMC, 2002 LS6.

    1991 GMC Syclone #1428

  2. #2
    Join Date
    Nov 2003
    Location
    Denton Texas
    Posts
    20,540
    Damn, Lance, you building a show truck or what?!?! Get that thing running so you can show me how an LS1 is supposed to run in an XCAB OBS.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  3. #3
    Join Date
    May 2004
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    LMAO! No days off yet so I figure I have a little time to play with the wiring when I get home each night. Dude, I'm so close! One weekend of humpin it at I'll be ready to do some tuning.

    Here, maybe this will make you feel better........


    97 GMC, 2002 LS6.

    1991 GMC Syclone #1428

  4. #4
    Join Date
    May 2003
    Posts
    60
    If you're having the PCM tuned, have the tuner change the high and low tach resolution to 3 for both fields.This will make your tach work without having to buy a converter. It will get the tach within 100rpm of what it should be reading. Down low its dead on, but above 3500rpm its off by just a hair. ABS, speedo etc all work if you just match all the circuit #s when wiring. My speedo reads 2mph higher than what the PCM says, but that can easily be fixed in the PCM. I'd rather have it read high tho as I have a heavy foot...

    Wiring shouldn't be a problem. Just match circuit #s, if it doesnt match, do not hook it up. Everything worked flawlessly on my swap besides the fuel level sensor as the PCM handles that completely differently between OBS with OBDII and NBS.
    Old: 1998 K1500 White ext cab stepside, vortec 350. Stock besides Volant intake.

    New: 1998 K1500 with stock LS2 besides LQ9 truck intake and 8.1L Marine injectors. Dynotuned, 350rwhp, custom 3.5" exhaust, '02 F-Body Racetronix fuel pump setup. All wiring, exhaust, motor brackets done in shop.

  5. #5
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    May 2004
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    Time2kill, Thanks for theinput, what year model is your truck?


    97 GMC, 2002 LS6.

    1991 GMC Syclone #1428

  6. #6
    Join Date
    May 2003
    Posts
    60
    <div class='quotetop'>QUOTE(NITROUS &#064; Apr 9 2006, 01&#58;09 PM) [snapback]49693[/snapback]</div>
    Time2kill, Thanks for theinput, what year model is your truck?
    [/b]
    Mine is a &#39;98. White ext cab with the stepside box. If you have any questions just let me know. I MIGHT have wiring diagrams and connector end views for your truck if you need them. My manuals are complete back to &#39;98, but I have some stuff as far back as &#39;96. I can take a look if you need anything.
    Old: 1998 K1500 White ext cab stepside, vortec 350. Stock besides Volant intake.

    New: 1998 K1500 with stock LS2 besides LQ9 truck intake and 8.1L Marine injectors. Dynotuned, 350rwhp, custom 3.5" exhaust, &#39;02 F-Body Racetronix fuel pump setup. All wiring, exhaust, motor brackets done in shop.

  7. #7
    Join Date
    May 2004
    Posts
    2,120
    Cool, Thanks for the offer. I&#39;ve got 96,97 and 98 factory manuals from GM but the wiring doesn&#39;t match on some of the circuits like it shows, close though. I bought HP tuners so I&#39;ll be tuning it myself for now. I&#39;ve talked to Allen about a mail order tune if I can&#39;t handle it. I&#39;ve had the truck down this long so no need for me to get in a hurry now. I&#39;ve added a small 3x5 fuse box with relays to work the fans and whatever else I want to add. It will be tucked beside main fuse box by the C100 connector. Should look very clean. How did you hook the ABS back up. I know what I&#39;m going to do but I&#39;m curious if you&#39;re doing the same.


    97 GMC, 2002 LS6.

    1991 GMC Syclone #1428

  8. #8
    Join Date
    May 2003
    Posts
    60
    <div class='quotetop'>QUOTE(NITROUS &#064; Apr 9 2006, 03&#58;21 PM) [snapback]49697[/snapback]</div>
    Cool, Thanks for the offer. I&#39;ve got 96,97 and 98 factory manuals from GM but the wiring doesn&#39;t match on some of the circuits like it shows, close though. I bought HP tuners so I&#39;ll be tuning it myself for now. I&#39;ve talked to Allen about a mail order tune if I can&#39;t handle it. I&#39;ve had the truck down this long so no need for me to get in a hurry now. I&#39;ve added a small 3x5 fuse box with relays to work the fans and whatever else I want to add. It will be tucked beside main fuse box by the C100 connector. Should look very clean. How did you hook the ABS back up. I know what I&#39;m going to do but I&#39;m curious if you&#39;re doing the same.
    [/b]
    I used a 2002 5.3 4wd 1500 harness when I did my swap. I used the stock &#39;98 fuse box. I just started on each connector on the new harness, and matched all the wires that had matching circuit numbers to the old truck. I remember there being a couple of ABS wires, all had matching circuit numbers so I just hooked them together. Then make sure you connect all the VSS wires and ABS will work. I didn&#39;t have to do anything special to make anything work on the truck.

    I don&#39;t have my efans hooked up yet, but I have a factory harness off a NBS with the relays and stuff all on it. I just need to run two wires to the PCM, and the harness plugs into the fans. Then just need to enable the fans in HP Tuners and thats all ready to go. I was in a hurry, so I just threw the stock 350 fan on for now. Truck never goes over 190*

    For the pink ignition wires that did not have matching circuit #s, I ran them all to a terminal strip that I got at radio shack. Then I ran a pink wire coming out of the firewall to a relay, and had the relay hooked up to Battery positive, and the relay 12v out going to the terminal strip. That way I won&#39;t be overloading the ignition circuit by running all the pink wires off the new harness to one or two pink wires on the truck. The relay tucks in nicely under the stock fuse panel out of sight.

    The only quirk that I havn&#39;t been able to figure out, is that now I can pull the truck out of park without having my foot on the brake. Neutral safety still works correctly with starting, so need to worry about it starting in gear, but the solenoid that locks the shifter in place doesn&#39;t kick in like it should. I&#39;m not going to worry about it though as it doesnt bother me.
    Old: 1998 K1500 White ext cab stepside, vortec 350. Stock besides Volant intake.

    New: 1998 K1500 with stock LS2 besides LQ9 truck intake and 8.1L Marine injectors. Dynotuned, 350rwhp, custom 3.5" exhaust, &#39;02 F-Body Racetronix fuel pump setup. All wiring, exhaust, motor brackets done in shop.

  9. #9
    Join Date
    May 2004
    Posts
    2,120
    Sounds like a neat installation also. I&#39;m using a Camaro harness so it&#39;s a little different. I figure I&#39;ll tie the yellow and black wire into the Camaro VSS back to the ABS. Then I&#39;ll tie the purple wire back to the Data link connector and the other purple to the brake switch and the ABS is complete. As far as the Cruise control wire LT BLue w/ black stripe goes, It&#39;ll go straight from the PCM to the Cruise control module. How did you make the inlet air actuator for the A/C work? The old PCM did it and there&#39;s not a place for it in the new PCM. Did you just aplly power to it and let it recirculate in the cab all the time?


    97 GMC, 2002 LS6.

    1991 GMC Syclone #1428

  10. #10
    Join Date
    May 2003
    Posts
    60
    <div class='quotetop'>QUOTE(NITROUS &#064; Apr 9 2006, 03&#58;43 PM) [snapback]49705[/snapback]</div>
    Sounds like a neat installation also. I&#39;m using a Camaro harness so it&#39;s a little different. I figure I&#39;ll tie the yellow and black wire into the Camaro VSS back to the ABS. Then I&#39;ll tie the purple wire back to the Data link connector and the other purple to the brake switch and the ABS is complete. As far as the Cruise control wire LT BLue w/ black stripe goes, It&#39;ll go straight from the PCM to the Cruise control module. How did you make the inlet air actuator for the A/C work? The old PCM did it and there&#39;s not a place for it in the new PCM. Did you just aplly power to it and let it recirculate in the cab all the time?
    [/b]
    I&#39;d have to look at the details to be sure on the ABS wiring, but all the colors from the new harness matched to what was on the truck. The yellow & black VSS wire I believe goes to the actual VSS sensor. I believe purprle and/or purple & white went to the firewall and to the ABS. I&#39;d have to double check my connector end views. If you are mixing and matching wire colors, then its not being hooked up right. Same thing with the cruise control, all the colors should match up and work just like they did on the old harness.

    I did not hook up the air inlet actuator wire to anything. It&#39;s just taped off and tucked off to the side. The A/C recirculation works just like it should, if I turn the A/C to max, it comes on, or if I hit the button, it comes on. I&#39;m guessing that wire was just some sort of output to the PCM for some sort of control that the new PCM does not use.

    The air recirculation gets it power from the red wire with a single 1 pin connector on it that goes through the firewall. The 1 pin connector for the red wire is right by the other connector under the glove box that runs out through the firewall.
    Old: 1998 K1500 White ext cab stepside, vortec 350. Stock besides Volant intake.

    New: 1998 K1500 with stock LS2 besides LQ9 truck intake and 8.1L Marine injectors. Dynotuned, 350rwhp, custom 3.5" exhaust, &#39;02 F-Body Racetronix fuel pump setup. All wiring, exhaust, motor brackets done in shop.

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