Altenator Question(s)

Discussion in 'GM Electrical Tech' started by MightyMax, Jun 21, 2010.

  1. MightyMax

    MightyMax Rockstar 100 Posts

    Here is the problem.
    My voltage guage on the dash sits around 10 - 12 volts and of course battery light comes on (it seems no
    voltage is getting from altenator to battery).
    I put a volt meter on the battery (pos and neg posts) and it shows about 12 volts.
    I put the negative probe on the negative post of the battery and the positive probe on the wire attached
    to back of altenator (engine off), and it shows around 12 volts. So that leads me to believe the wires
    are fine between battery and altenator.
    But of course once I turn the engine on all it will show is voltage of the battery. Tests confirm no
    voltage from altenator (my battery tester and Advance Autos tester).
    Now some times the system will correct itself, like if I make a left turn (not right turns), or last night
    when I was working on the truck in my driveway (slight incline) he was fine until I moved him back a
    little bit in the driveway.
    It is not the altenator, I had put a refab in him, but the problem persisted so I installed a new one
    last night and the problem still continues. So 3 altenators have been in the truck (the original, the
    refab and now the new one).
    So this leads me to believe there is a wire somewhere that is swinging against the chasis....
    But I have been looking at the wires and all appear to have their insulation on them or are in
    electrical tape.
    These wires I have inspected are in the engine compartment area.
    -- Are their areas elsewhere I can check? Would wires in the dashboard cause a similar problem?
    -- I saw something talking about the wires going to the starter. I have only glanced at those
    wires. They appear to be in good shape and not touching any metal. Is there something else
    I should be looking at when inspecting the starter?
    -- Is there anything else I am not thinking of or looking at that I should?
  2. Enkeiavalanche

    Enkeiavalanche Loving the Outdoors Staff Member 5+ Years ROTM Winner 5000 Posts

    What year and model truck? How many miles? It could be the Regualator..
  3. MightyMax

    MightyMax Rockstar 100 Posts

    '91 Chevy
    The chasis is over 500K miles.
    The engine is about half that...

    Where is the regulator located?

    ---------- Post added at 10:42 AM ---------- Previous post was at 09:21 AM ----------

    Ok, I am thinking it might be related to the after market FOG LAMPS that the people, that owned the truck before I did, installed.

    I have disconnected the lamps from the relay switch (which appears to be connected to the head lamps) and will drive the truck around and see what happens.

    Does anyone know or have wiring instructions/diagrams for fog lamps?
    I would like to re-run these guys to their own circuit.

    ---------- Post added at 12:40 PM ---------- Previous post was at 10:42 AM ----------

    Ok, not the fog lamps. Problem still occurred after disconnecting the relay block for the fog lamps.

    I have noticed that when I push the gas, the initial incline of the front end will correct the issue and once the truck levels out from that, the problem starts again.
    So it seems like a swinging wire, or something making/not making contact.

    Can a relay switch cause this behavior?
    Or does a relay switch do something else entirely different?

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