Aparrent low voltage with a 1995 Suburban

Discussion in 'GM Electrical Tech' started by Chev2tehCore, Sep 3, 2007.

  1. Chev2tehCore

    Chev2tehCore Member

    I have noticed for a long time that my 1995 Suburban doesn't read as high in voltage as other cars I have owned. It shows 14 at the absolute highest and is on the line between 9 and 13 if I am running a lot of things such as front and rear fans with the radio and the lights on. All of the other Chevy vehicles I have owned have run between 13 and 16 all the time.

    I have replaced the alternator and the battery but it hasn't seemed to change anything. in my experience with other cars I have never seen the volts so low yet the car still starts. What is the chance I have a bad volt gauge?
  2. Crawdaddy

    Crawdaddy All hail the Mad King!! Staff Member 5+ Years 1000 Posts Platinum Contributor

    the tyical output voltage for an alternator is between something like 13.6 and 14.4 volts, so if you got over 14.5 volts on other vehicles, I'd be a little worried about them. However, between 9 and 13, that's low, like the alternator's failing. You may have some nasty underlying problem that's causing this. I know a camp truck that I used to run has/had a nasty electrical issue we never fully tracked down. It would eat alternators for breakfast, lunch, and dinner. Eventually, we got tired of putting new alternators on it and retired it. I'm going to leave the floor open for other people, because I don't have any further ideas concerining your issues :(
  3. Cableguy

    Cableguy Epic Member 5+ Years ROTM Winner 1000 Posts

    I would go with actual measurement with a volt meter. Don't be to bothered by the guage there notorious for an accurate reading. As long as your in spec like Crawdaddy says your OK, higher than 14.5 VDC will usually start blowing bulbs and other assorted craziness. Mine in my work van drops to 11VDC (or so the truck says) when my 4000 watt inverter is on under a load of 120vac at 10amps but when I take a batt measurement its fine. Don't put to much stock behind gauge.
  4. TA Dave

    TA Dave Member

    I agree with Cableguy. It's probably the guage if you replaced the alt and the battery and things didn't improve.

    IIRC, Autozone and Advanced, ect will test the car for you, for free.
  5. Chev2tehCore

    Chev2tehCore Member

    I suspect it is a gauge and not an actual problem because the lights are bright, the fans seem to be turning normal speed, and when I put it on the battery charger it shows as fully charged within an hour with a 2 amp charger.

    My Camaro always ran on the line between 14 and 18 and it never blew bulbs or had any eletrical issues. Every Chevy I have owned ran above 14 by the guage except this one. I have checked the battery connections and nothing seems loose. I am at a loss of what to try next.

    We only have Schucks(Krager) and Napa in this town. When they do a check do I have to take the alternator off? Can they test it while it is running to see what the real output is?
  6. 95CTburb19

    95CTburb19 Epic Member 5+ Years 1000 Posts

    haha with my 95 burb when i put my turn signal on the gauge goes back and forth at the same speed as the lights. Also drops when i turn on my headlights and use my interior lights. but again its an 800 dollar truck that starts every morning so i have no complaints. :money:
  7. Chev2tehCore

    Chev2tehCore Member

    How do I find out which Alternator I shoudl have?

    The Auto parts store gave me a 105 amp alt when I replaced it. I am told that 1995s also came with 130 amp alternators.

    How do I know which one I am supposed to have?

    Can I use a 130 when it came with a 105?
  8. Crawdaddy

    Crawdaddy All hail the Mad King!! Staff Member 5+ Years 1000 Posts Platinum Contributor

    There should be no reason why it won't work. I know for my 91, there were 3 different alternators that the truck could come with, and they all have the same specs with the exception of output ratings...
  9. unplugged

    unplugged Epic Member 5+ Years 1000 Posts

    I have the same symptom on my 93 burb. When I have the lights, stereo, and ac on full bore, the gauge dips well below 14 volts. I've driven many miles with it this way and no trouble starting so I haven't dug into it. Voltmeter at the battery confirms 13.8vdc. Could be a problem similar to later model trucks that have stepper motor issues. I have a hunch that it is a bad chassis ground, or maybe wiring to the instrument cluster. I swear the speedometer was 'ticking' with the turn signals one time when I was at a light. The speedo swept from 0 and higher in tune with the turn signal. Gremlins!

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