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Thread: Fuel Gauge

  1. #1
    Join Date
    May 2003
    Posts
    60
    What are you guys doing with the fuel gauge? I have a '98 1500, and the old PCM had a fuel gauge output wire on it, but the new PCM ('02 1500) transfers the fuel guage signal across the Class 2 Serial Data. Is there anywhere I can run the fuel gauge wire to so it can pickup the signal for fuel level?
    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.

  2. #2
    Join Date
    Nov 2003
    Location
    Denton Texas
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    Hmmm, never had that issue before but mine was a 92 and 93 swap. The stock fuel gauge signal works fine on mine without feedback to the PCM. I guess that's an OBD2 issue.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  3. #3
    Join Date
    Jan 2006
    Posts
    35
    I have run into this problem with my C5 guage swap. the camaro program doesnt look for the data for fuel tank level or oil pressure, however this data is transfered to the guages across the serial data bus. Im going to try directly attaching the wire to the input on the guage. if that doesnt work then im going to get the PCM reprogramed with the corvette setup which will look for these inputs and transmit across that bus. I would check to see if this is something you can try

  4. #4
    Join Date
    Jan 2006
    Location
    Las Vegas, Nevada
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    328
    If your 98 gauge is analog you could bypass the PCM by intercepting the fuel level input to the pcm and connecting it directly to your fuel gauge... (the old wire that came out of the PCM)

    1965 C-10 shortbed stepside, 2003 5.3/4L60E conversion. Power steering, tilt wheel, power front disc brakes, 3.73 one wheel peel, 2.5/4 inch drop, relocated fuel tank and battery, 2002 Silverado buckets and console. Swap Pics
    1968 Camaro 95LT1/4L60E lots o' mods Web Page
    1961 Corvette project.......... C-4 suspension and brakes, 02 LS1/T-56 awaiting installation Pics

  5. #5
    Join Date
    May 2003
    Posts
    60
    <div class='quotetop'>QUOTE(kwkenuf &#064; Mar 29 2006, 01&#58;54 PM) [snapback]48622[/snapback]</div>
    If your 98 gauge is analog you could bypass the PCM by intercepting the fuel level input to the pcm and connecting it directly to your fuel gauge... (the old wire that came out of the PCM)
    [/b]
    The &#39;98 guage is analog, and I have tried connecting the guage wire into the fuel level sensor although the gauge doesn&#39;t read right at all. My fuel gauge was previously messed up before the motorswap, so I had replaced the fuel level sensor thinking it was that. Now I&#39;m thinking that there is a short somewhere in the wire.
    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.

  6. #6
    Join Date
    May 2003
    Posts
    60
    Well, without the gauge hooked up, the PCM reads the fuel level sensor perfectly fine, but as soon as we connect the gauge wire, it completely throws the reading off in the PCM. Doesn&#39;t look like there is any way to make it work with the new PCM unless we can find a way to convert the signal somehow.
    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
    Nov 2003
    Location
    Denton Texas
    Posts
    20,540
    I wonder if you can use a sending unit out of an earlier model truck like the 92-93 and wire directly to the gauge.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  8. #8
    if using the 98 truck cluster youd use the OE wiring. the PCM could
    careless about fuel level.
    on mine i just grounded on and used the other for the gauge.
    once i get my 03 cluster, ill rewire the PCM, like you said the PCM
    signals are class2 serial and most of the cluster uses this signal.

    airdeano

  9. #9
    Join Date
    May 2003
    Posts
    60
    <div class='quotetop'>QUOTE(RedHeartbeat &#064; Mar 30 2006, 10&#58;31 PM) [snapback]48831[/snapback]</div>
    I wonder if you can use a sending unit out of an earlier model truck like the 92-93 and wire directly to the gauge.
    [/b]
    This could be a possiblity. Although the old PCM sent a 5V signal to the sensor, and the new PCM is sending ~8V signal to the sensor. I don&#39;t think it would be a problem though to just run a different 5V reference wire though, but we need to figure out why the gauge is throwing the signal off first.

    So far we havn&#39;t had any luck just running the gauge without running it back to the PCM either. We can get the gauge to respond to the fuel level sensor, but it is way off. Empty comes up at about 1/2 on the gauge, and full is pegged out about 40* past F.
    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.

  10. #10
    Join Date
    Jan 2006
    Posts
    35
    You might want to try adding a resistor inline to drop the power to 5V then run it directly to the guage. If your applying a 12V signal to the sending unit it will be off.

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