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  1. S

    PCM issue?

    Is that something that can be tested with a meter for differences in voltage at different points from the alt and battery? What is an expected difference in voltage between alternator and battery posts. If I remember correctly, I saw a couple tenths less at the battery.
  2. S

    PCM issue?

    Yeah, I was curious what that was then I came across information on this system. Connections look good and tight. I've been driving the last couple of days and no problems or engine codes, just the lower reading on the volt gauge than I'm accustomed to. Will take a bit but I think I can get used...
  3. S

    PCM issue?

    So I've learned about the battery generator control module this morning, and low and behold, driving with tow mode on or my headlights on, voltage stayed over 14v. Is there any way to check if my module is going bad? I've had MAF related codes thrown twice when the volts were low due to "fuel...
  4. S

    PCM issue?

    I brought in the alternator to test it out, and it tested fine on the bench test. 13.3 volts. The guy did another warranty exchange for me. Things went great... for the first run at idle for 20 minutes, then the 3 minute drive to pick up my kid from day care, it started to show signs of the...
  5. S

    PCM issue?

    So the drive home from class, I watched the scanner vault reading. Initial voltage kicks off at 13.3 and rises to 13.5 within a minute. Then a minute later, it starts to lose a tenth roughly every 30 seconds until i pull over to shut it off and start it up again. That really sounds like the...
  6. S

    PCM issue?

    I checked voltage at the junction block grounded to the alternator and saw around 12 volts between the first and second alternator change. I have a Bluetooth odb adapter and it's reading 11.9 volts when the gauge drops, which tells me I'm running off the battery... This thing is really...
  7. S

    PCM issue?

    I got a 2006 Yukon XL Denali around 87000 miles a couple weeks ago and have been trying to work out a charging system issue. Initially, it had a bad battery when I bought it, so I picked up an optima red top. On the drive home, the volts dropped to where it was running off the battery. I...
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