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Thread: Fuel Level Incorrect

  1. #1

    Default Fuel Level Incorrect

    Holley HP ECU
    7" Digital Dash Firmware V6 - 230
    Aeromotive fuel cell 0 - 90 Ohm sending unit.

    Searching through the forums I'm experiencing the same problem as a couple others here. With the fuel level sending unit out of the cell and grounded to the battery, and testing the Ohms at pin 13 of the I/O module, resistance readings are perfect. 3 Ohms empty, 93 Ohms full. However, if the Custom Ohms in the fuel level table are programmed 0 - 90 the fuel level never reads above 63% full. Spoke with tech support several times and no progress has been made.

  2. #2

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    Seems to be the same for the Pro Dash also. I'm at about 1/2 tank and read about 39 Ohms with noting, but the DVO meter hooked up. Once I attach the Pro Dash my Ohms go to about 70 on the dash readings.

    Now with the DVO meter hooked up, but the Pro Dash off the Ohms reading is correct on my meter as soon as I power the dash the Ohms on the meter match the dash at about 70.

    This is on V6 Build 220 for the Pro Dash on input 7 for the fuel level. No response from tech support on this problem. -Greg

  3. #3

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    Found this link: https://speedmaxinnovation.com/produ...-7-holley-dash. In previous research, I think I found a thread that stated the fuel level ground wire needed to be pinned to the I/O module as well, but I can't find the thread any longer.

    It's interesting that the link above is a harness doing exactly that, but it does not use the I/O module. They found a connector that goes straight into the dash where the I/O module plugs in. Can anyone confirm this? -Chris

  4. #4
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    Default

    Quote Originally Posted by Chris@Pauls View Post
    In previous research, I think I found a thread that stated the fuel level ground wire needed to be pinned to the I/O module as well, but I can't find the thread any longer.
    https://forums.holley.com/showthread...034#post234034 (Digital Dash Fuel Level I/O Ground)
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  5. #5

    Default

    This was indeed the fix, fuel level now reading exactly what I've programmed into the Custom Ohms chart.
    I ran PIN 2 on the I/O module all the way back to the sending unit. Pin 2 & Pin 6 are labeled just grounds for the I/O module.

    My theory for why this is the resolution, is that the I/O module actually needs to be grounded. (NOT noted in the instructions part #553-432.) Otherwise when using the CAN to the HP ECU, the dash is only grounding through CAN which would skew the resistance on your fuel level sending unit when plugged in.

    I tested this by running PIN 2 to chassis ground instead of the sending unit and it gave the same result although it was still off 3% compared the my Ohms chart. I could actually move pin 2 on & off my chassis ground and watch the fuel level % change on the Digital Dash. Hope this helps anyone else and should be included in the Digital Dash/IO instructions in my opinion.

  6. #6

    Default

    I've never tried to run the signal to the Digital Dash, but I wire the sending unit (ground & signal) to the ECU and use that for the Digital Dash as an input.

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