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Thread: Cam tune Silverado. Electric fans not working.

  1. #1
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    Cam tune Silverado. Electric fans not working.

    I am working on a 4.8 2007 Silverado. Installed a new camshaft and some bolt ons. I have been working on the tune. Got my Maf squared away and have been working on my idle. Well it's December here in SC, so I didn't notice at first, but for some reason my fans will not operate now. I didn't change anything in my tune at all under the system tab yet. I compared it to my baseline tune I pulled. The factory tune calls for 43% at 217.4*. I watched via VCM Scanner and etc crept into the 220* range. I can command electric fans on with the scanner, but the tune will not command it(well, I cant say it's actually not commanding it, I don't know how to watch the outputs in real time, if that's even a thing.) Any help would be appreciated.

    Attached are the baseline and newest running tunes. Could this be related somehow to how I wrote the tune to the truck? Should I write all instead of write calibration?


    4.8 baseline.hpt
    base tune 3.1.hpt

    Last edited by seweeperstang; 12-22-2019 at 09:40 AM.

  2. #2
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    At the time of tuning I was on 4.5 1078 beta. I just went thru the update of 4.5 1139 Beta a few mins ago. I am using the Beta so I keep up to date with the jtec stuff as it rolls out.

  3. #3
    Tuning Addict blindsquirrel's Avatar
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    You can log status of Fan 1/Fan 2 in the scanner.

    Second file won't open, '...part of a remote tuning network blah blah...'

  4. #4
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    Quote Originally Posted by blindsquirrel View Post
    You can log status of Fan 1/Fan 2 in the scanner.

    Second file won't open, '...part of a remote tuning network blah blah...'
    base tune 3.1.hpt

    Not sure why that was the case, but I just cleared the master slave. The populated number then disappeared. Maybe it will work now.

  5. #5
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    Well I logged the fan 1 and 2. But the tune never commands them to turn on. When I I use the scanner to turn them on, it shows the output turning on. But nothing yet as to why the tune isn?t doing this.

    If anyone could assist I?d appreciate it.

  6. #6
    Advanced Tuner IARLLC's Avatar
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    You are not commanding the fan on until about 226 degrees.

    First:
    Go to System>Fans>Relay Controls>State vs Desired %
    This table shows you what % has to be reached in order for 0>1 transition (usually fan on low) 50 right now, 1>2 (usually fan on medium or high depending on the table just below and relay set-up. Your 1>2 is for high fan speed) 90 right now, 2>3 (often not used. Yours is not used. Depending on relay system it can be for fan on high) 99 right now, then at the bottom of the table it shows you at what % it will cycle each level back down.


    Second:
    Go to System>Fans>Control by %>Desired
    This table shows you what % is assigned to what temperature.
    217.4 degree is at only 43%, 221 degrees is at only 48%, 224.6 degrees is at only 48%, and the low fan will not come on until 50%.......
    228.2 degrees is finally at 52%. Since it will come on low at 50%...that will be half way between 224.6 and 228.2= 226.4
    Next you will hit high fan speed (90%) at 231.8
    Behond 90% does not matter for you.

    Your fan setting largely relate to your thermostat opening temps.
    Stock 2007 5.3 rigs usually turn on the low fan speed at 195.8 and go up gradually to 231.8.

    With a cooler stat we need to cycle the fans on earlier. I can post stock tables later. I have to go for now.