98-99 Suburban K1500 with charging problems.

Discussion in 'General Chevy & GM Tech Questions' started by Bredin, Dec 21, 2011.

  1. Bredin

    Bredin Rockstar

    Hey everyone,

    My 99 K1500 Suburban (old body style, same as 98) with a 5.7L Vortec engine is having some problems charging...
    It goes from charging at 13.5V down to 11.2 and lower, and then jumps back up to 12 to 13 sometimes...

    I know that my A/C Compressor is bad, but the clutch is not spinning, but it is giving off a whining sound when the A/C pulley is spinning.
    Could the A/C Compressor cause the alternator not to charge properly, or am I lucky enough to have a bad alternator (as well as a bad starter, bad water pump and a bad master brake cylinder or power booster...)

    If it's a bad alternator, would either of these alternators that I found on eBay fit in my truck?


    http://www.ebay.com/itm/H2-ESCALADE...del:Suburban 2500&vxp=mtr&hash=item4160001587

    I am looking for a high output alternator, since I am running dual batteries, sub woofer etc...

    ---------- Post added at 11:09 AM ---------- Previous post was at 11:08 AM ----------
    also, how can you tell what amp alternator is already installed on the truck?
    (solved the Q how you can find out what amp the alternator is... it is stamped on the housing of the alternator... just get a steel brush and brush the housing on the upper passenger side and you should be able to see some numbers and letters stamped in... this told me 100A...)
    Last edited: Dec 21, 2011
  2. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    The belt is tight and steady and turns the alternator with no slippage, slop, looseness, or wobble?
  3. Bredin

    Bredin Rockstar

    tight as a 18 year old virgin... :x
  4. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    Wires connected to the alternator are all in good shape?
  5. Bredin

    Bredin Rockstar

    The exiter (sp?) wire looks like it has seen better days... but there is no change in the charge or lack of charge I should say.
    It's been going from 14.3V while I was driving around right now, to 11 (while driving and at idle)...

    I think it's the alternator that is going on me... but I think that I should get a new wire and plug as well for it, just to have everything new. Now I just have to find the funds to be able to do that... anyone who would like to lend me some money? lol I take paypal at info[MENTION=23758]Bredin[/MENTION]s.com lol (what... it never hurts to ask right)... lol
  6. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    If you've done a 'tug test' (tug on wires and make sure they're still secured) then the wires/connectors are likely ok. That and the belt were worth a cursory look before going directly to the alternator. If it were me, my next step would be to take a voltmeter to the alternator, itself, to see what it's putting out at its terminals. This will tell you if it's the alternator or something between it and the vehicle.

    If your voltage test at the alternator terminals shows fluctuation like you're seeing at the gauge then you likely need to replace the alternator. If not then the issue may be with the vehicle wiring and you might test the wiring to see what's actually being received by the battery from the alternator, as it could be the wiring from the alternator to the battery. If both your voltage testing at the alternator terminals and at the battery-end of the connections from the alternator show no issue then it's time to take a hard look at the gauge's connection ... or perhaps the stepper motor of the gauge, itself.

    As for what alternator to consider if you do need to replace yours, I believe the 98-99 K1500 burbs were offered with a standard 100amp alternator and and optional 140 amp 'high capacity' alternator from the manufacturer. If you move to the larger OEM size be sure to replace the belt with what's intended for that size, too, as different belts were used with each size. Your make, model, year, engine size, and plug type into the alternator will determine what alternator you must buy.

    Pertaining to aftermarket, high output alternators, they are spendy -- usually close to ~3x the cost of a replacement alternator in the optional OEM size.
    Last edited: Dec 21, 2011

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