Jump to content

U18A2

Andy2016
 Share

Recommended Posts

Andy2016 New Member

Andy2016

Posted
Posted

Ive been chasing this coms fault for awhile, it's ecm is not communicating with the FPCM, at first I read 120 ohm on 6 and 14, I replaced the FPCM, it was programmed already from GM, replaced end of 2025. Over the past week Ive had time to start by cleaning grounds, removed the wire loom at the rear of the truck to expose all of the wires to the 4 modules above the spare tire, Ive removed all connecters and inspected, after I checked ohms from the resistors through every module with connecters back in. Its weird, must of had a pin that had pushed up, now Im getting 60 ohms, voltage is good also, still not communicating. I have 2 more ground that are on top of the dash to do and see if that fixes it. Ive checked the BCM, FPCM, TRCM, SPCM, ECM, main fuse box connecter, both side dash fuse boxes etc. Any other ideas would be great. Truck is well taking.

Andy2016 New Member

Andy2016

Posted
  • Author
Posted

CanHI 2.8 CanLo 2.2, nothing to Chassis ground from Pin 6 or Pin 14, 60 ohm on Pin 6 and 14, checked every connection, cut and removed tape from the middle of the truck to the rear, opened up dash also. Im leaning towards a bad FPCM again. Couldn't be bad straight from GM could it, hopefully warranty is still good, got the new one back in June of 25 and the light and code never went away after clearing codes. I furgured the new FPCM could not be bad and some have said a wiring issue, thats why Im at this point. 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.5k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,881
    Total Members
    8,960
    Most Online
    tararebecca
    Newest Member
    tararebecca
    Joined

  • Who's Online   5 Members, 0 Anonymous, 648 Guests (See full list)

  • Latest Articles

  • Posts

    • tararebecca
      2027 GMC Sierra: Official Discussion

      By tararebecca · Posted

      I agree, simplicity and reliability matter more as vehicles get more complicated. A V8 work truck option with fewer electronic features and a stronger warranty would definitely appeal to a lot of buyers who use their trucks for real work. Customizing it with trusted outfitters is often the best way to get exactly what you need.webcrimsNY
    • artistemorbidity
      2026 Sierra 1500 Denali - Sound upgrade?

      By artistemorbidity · Posted

      I’ve heard similar complaints from newer vehicles where the factory “premium” systems don’t always live up to expectations. A good installer should be able to improve the sound without turning it into a bass-heavy setup. I’d look into upgrading the front speakers, adding a quality DSP amplifier, and possibly improving sound deadening first—those changes usually make a much bigger difference than just adding a subwoofer. Hopefully someone local can recommend a reputable installer in the Las Vegas/St. George area.
    • Grumpy Bear
      The Peckish Synapse

      By Grumpy Bear · Posted

      Do you remember that Harley Davidson was more successful (solvent) when it produced about 60% of the market demand (by design) and forced wait times of up to three years? Even when your turn came around it was, "Take what we are giving you or move to the back of the line and start over". HUGE markup's were 'normalized' and dealer killed. 40% markup and no floor plan? What's not to love? Greed will kill them yet. They have surplus production and customer base is tanking. And still they think nosebleed pricing will work.  
    • newdude
      Me too……..

      By newdude · Posted

      The engine was done as part of the 6.2 recall?   You'd have to see if your VIN also has the 6.2 engine special coverage on it.  Coverage number is N252494003.  If you have this, your engine is covered under this and NOT the GM replacement part engine warranty which is 3yr/100k from the date of install.  The 3yr/100k mi warranty is in effect for non warranty purchases.     This is not any different if it was replaced under warranty without a recall or special coverage.  So if you had a 5.3 and it popped at 3 years in at 50,000mi during the 5yr/60k powertrain, the replacement engine would not get the 3yr/100k, and instead gets the remainder of the 5yr/60k as coverage.     So N252494003 gives 10 years or 150,000mi of coverage, which ever comes first, starting at the vehicle in service date.  So if your in service date is 01/01/2022, N252494003 gives you special coverage of the engine until 01/01/2032 or 150,000mi, whichever comes first.  So if your start date was 01/01/2022, you'd have left 5 years and 4 months (lets round to august 1st), or 62,000mi left of coverage.   So you need to know your in service date to know how much coverage is left.  
    • CamGTP
      Injector update

      By CamGTP · Posted

      Okiee dokie there bud, way to take things to the extreme.   I guess you missed the whole point and take things way to serious. I installed different EV6 style injectors that just so happen to be larger in my car running the same LQ4 engine and with a better spray pattern than the stock style injectors and I noticed no difference in the idle quality. Kinda was my round about way of saying that even if you put the same size but better style injectors in your truck, you will likely see the same thing.    I'm sure you're great to have conversations with in person if that's how you act through a keyboard. One little things sets you off and now I guess my dick is all up in your face.

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...