Me and my GMC

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by Turbogus, Apr 25, 2016.

  1. Turbogus

    Turbogus Active Member 1 Year 100 Posts

    I'm finding more places where it straightens itself out but after yesterdays' grocery shopping that damm Engine light came on again. Discopnnected the negative cable from the battery terminal this afternoon to force restart of the ECM (poor man's OBD2 reset).
     
  2. Turbogus

    Turbogus Active Member 1 Year 100 Posts

    SO it continues and even after an o2 sensor replacement that cleared the Engine Light it only lasted 4 days before it came on again. back to poor man's reset. On a good note I Armor Alled all of the door gaskets and rubber door electrical conduit after I noticed some dried out and cracking seals on the rear and one of the passenger door bottoms. Man! some areas were jam packed with pine needles and other debris, I'm glad I got into it!
    Hopefully going to crawl under it soon and see what kind of trans. pan I have. Despite it working fine I really want to do a trans. service as it is in unknown condition since I got it a month ago.
     
    Last edited: Jul 3, 2016
  3. Turbogus

    Turbogus Active Member 1 Year 100 Posts

    So I'm addressing the stripped out head on the negative terminal on this "new" side post battery (came with the truck), by introducing a 3/8 bolt (9/16 head) and looking more closely at the positive terminal I'm concerned with it's condition;
    The negate terminal now
    [​IMG]

    The positive Terminal
    [​IMG]

    The wire leadingfrom the terminal
    [​IMG]
    and I believe it feeds this ECU box as the wire dissapears underneath;
    [​IMG]


    If I go to the trouble of removing this box to replace the wire does it terminate in a spade or ring terminal or something else?
     
  4. Turbogus

    Turbogus Active Member 1 Year 100 Posts

    Seems this is a dead thread but just yesterday after the commute to work the truck wouldn't start (low voltage) borrowed a jumper box from the local shop I use and limper 'er over there they put a battery charger on it and I drove it home returning it to the shop today. I thought the low voltage (10-10.5 V) at the voltmeter was indicative of an issue but one of the mechanics said the voltage at the terminals is at 12.7 +/- which is sufficient. Mind you, back when I drove a '77 Chevy short wide and earlier a '76 Blazer the voltmeter always read upwards of 14.5 V!
     
    Last edited: Aug 4, 2016
  5. kennythewelder

    kennythewelder Rockstar 3 Years 1000 Posts

    The easy way to test your alt. Is to start the truck, then with it running pull the negative cable off the bat. If the truck stays running, it is running off the alt. and the alt is good, but if the truck dies, then the alt isn't working.
     
    thegawd likes this.
  6. RayVoy

    RayVoy Epic Member 5+ Years 5000 Posts

    A fully charged battery, at rest, will have a voltage of 12.6 volts.
    An alternator can output up to 14.4, normal charging is around 13.8 volts. However, as a battery charges, the alternator voltage will drop.
    A fully charged battery connected to an operating alternator will read 12.7 volts.
     
    kennythewelder likes this.
  7. Turbogus

    Turbogus Active Member 1 Year 100 Posts

    This image shows where the voltmeter nomally stays from statup early in the morning, until my 11 miles commute home. The specific gravity of the old attery was in the tank. New one is 12.4V static (engine off) and 13.7V idling with an external voltmeter. Dsconnecting the ground the motor still runs
     

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  8. RayVoy

    RayVoy Epic Member 5+ Years 5000 Posts

    12.4 and 13.7 proves, to me, that the battery and the alternator are good.
    Looks like a bad gauge, loose/poor electrical connections, or low PCM output.
    I don't remember your year, but there was a rash of poor solder joints.
     
    kennythewelder likes this.
  9. kennythewelder

    kennythewelder Rockstar 3 Years 1000 Posts

    I agree with Ray. It looks like a gauge or wiring going to the gauge issue.
     
    RayVoy likes this.
  10. kennythewelder

    kennythewelder Rockstar 3 Years 1000 Posts

    The gauge in my 97 is closer to 14. That is where it usually is.
     

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