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  • Name
    Nate Leatherman
  • Location
    Southeastern PA
  • Drives
    2018 Chevrolet Silverado 1500 Custom

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  1. Hi all, I’m new so I apologize if this is in the wrong place. I googled hi and low looking for an answer to this and found nothing, so I’m posting to try to help others. Today I tried to move my Tekonsha Primus IQ brake controller from my 2012 pilot to my new to me 2018 Silverado 1500. I had the GM wiring harness that came with my truck, so I spliced it to the Tekonsha harness from my Pilot, after cutting off the Pilot end. Im a commercial hvac service tech and used to working on vehicles as well, so this was all fairly mundane at this point. Well next I plugged in the brake controller to the junction box under that dash and got no lights. So I checked for power on the pins, nothing. Next I checked fuses, all good and had power. Next I google no power to brake controller plug every possible way I could think of and all I could find was a link to GM upfitters documents. This wasn’t totally unhelpful, but it was a little over my head at first. Well I dug into it and ended up removing the trailer brake control module above the spare tire and checking for power, I had 12v. There was lots of dirt in the harness so I sprayed the plug with electrical contact cleaner and applied some dielectric grease and plugged it back in. Now I had 12v under the dash too. Next I plugged in the brake controller again and still nothing. This is where things go downhill. I googled the pin designations for for my specific wiring harness model number from the pilot. The diagram I found indicated that I should have spliced red to blue and blue to red. I trusted the diagram and made the change. Plugged the brake controller in and nothing happened. About 3 seconds later I saw smoke from my brake controller wiring harness. I unplugged my brake controller as fast as I could. I still don’t understand what all went wrong, but that quick it ruined the little battery ground wire of the GM brake controller harness all the way back to the plug in the junction box under the dash. I was/terrified I damaged something in the truck, so I disconnected the negative battery cable and then disconnected all the plugs and removed the junction box to inspect it. I couldn’t find anything that looked damaged in the truck. Of course you really can’t see the board in the junction box though and checking the wires is really just a visual check. Hopefully nothing crazy turns up and hopefully my new brake controller and GM specific wiring harness work ok once I get them. Keep your fingers crossed for me!
  2. That sounds like a good idea. Not sure when I’ll get to it at this point, but I would rather do that than make changes to idle speed. I had read a very long thread with lots of peoples input saying that their brand new trucks had the slightly rough idle in gear and that it was due to GM setting the rpm’s too low for fuel economy reasons, but then there were also some saying fuel system and/or intake cleaning solved the issue. Is the Range module the best for just disabling afm?
  3. Thanks for the reply! Yes I am planning to look into the trans thermostat and keep an eye on temps in the meantime. Can most handheld tuners also adjust the idle speed? I’ve done a lot of reading so far and it sounds like that is one of the most reliable fixes for the rough idle in drive. It’s smooth as glass in park or neutral.
  4. Hi all, New GM truck owner here. Just bought a 2018 Chevrolet 1500 Custom. I am the second owner, truck has 132,****** miles but seems to have been well maintained and is in great shape. Currently has a leaking oil cooler line and a broken exhaust manifold stud, both for which are going to be fixed on Monday by the dealer under my 30 day powertrain warranty. I am aware of the afm issues and would like to disable it, unless I am advised otherwise here. I also have a relatively slight shake at idle in drive, which I understand is common. I plan to change spark plugs, change engine and cabin air filters, and fluids as soon as possible. I also plan to run some Liqui Moly through it, but if none of that corrects the rough idle, I’d like a tuner to raise the drive idle rpm’s a bit. That and disable afm are all I want out of a tuner, nothing else. So I’m looking for recommendations. I don’t want to spend a fortune on features I don’t need. The trucks purpose is mainly to pull my 3500 pound, 16’ travel trailer about 10 times a year. That and some general run around, getting things like lumber or mulch or firewood occasionally. I want to take care of it and have it last as long as possible. Thanks in advance!
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