98 Z71 battery drain problems

Discussion in 'GM Electrical Tech' started by Aftershock77, May 1, 2012.

  1. Aftershock77

    Aftershock77 New Member

    I have been dealing with the same issues most have with the battery being drained the next day. The problem started when I went and changed my oil of all things. Disconected the neg terminal and when I reconnected , started the truck ran around and the next morning my truck was dead. My first thought was a bad cell so I bought a new battery. Not the problem.
    Changed it out, did some more running then the next day dead again. Got a jump and started right up, ran with no problems. A friend thought maybe the alternator brushes going out that it was hitting a bad spot and draining the bat. Any thoughts?
  2. rileyjr16

    rileyjr16 Epic Member 5+ Years 1000 Posts

    Why would you disconnect the neg terminal to change the battery?

    Are you sure you don't have any lights on or something? The reason I ask is my 97 did the same thing and it was my underhood lights were staying on and not tripping off with the hood closure.
  3. The Heater

    The Heater Rockstar 100 Posts

    Based on your facts presented, I suggest that you scrupulously clean the negative and positive terminals and wire terminals for the battery. If the ground was not conducting properly (and you said it started when you disconnected the ground terminal), the alternator cannot transmit sufficient current to it to recharge it when it discharges while you are driving. This is purely based on what facts you presented.

    The ground circuit must be capable of conducting the same or more current as the positive circuit. If conduction is poor at the battery, there will be a problem.
  4. Aftershock77

    Aftershock77 New Member

  5. osgprometheus

    osgprometheus Rockstar 100 Posts

    First of all, why did you disconnect the terminal to change the oil? lol Second of all, how is your volt meter reading while you are driving? Did you do a load test on the battery? Does the battery cable spark when you connect it to the battery?
  6. Lerch98

    Lerch98 Member

    With the battery reasonably charged (not dead), engine and all lights and accessories off; disconnect the positive terminal and connect an ammeter between the battery + terminal and the battery cable. A digital multimeter works works well. Meter positive to battery positive, meter negative to battery cable. Measure the current draw. Should be less than 100 milliamperes (0.100 amperes). There will always be a little current draw from the ECM.
    I had an ex-wife that could kill car batteries by leaving the dome light on. Could not tell during the day, but would leave it on for days and the battery was toast. Couldn't tell her notin' so I just removed the courtesy light fuse.
    Also, I have seen aftermarket accessories cause current draw and more commonly due to sub-standard workmenship and creating a draw though bad wiring (shorted) (you'll be surprised how many time I have seen that.)
    Good luck with your current draw issue. One thing you can do is systematically disconnect 1 thing at a time and note the change in current.
    If you don't have a multimeter or amp-meter you can us a 1157 bulb (12 volt 12 watt) bulb in place of the ampmeter, If bulb glows you got current draw.
  7. marcski

    marcski New Member

    And if light stays on as decribed above - start removing fuses until light goes out and you will find circuit that is probably the problem - be sure that you disable door jamb switch so your not getting reading from the interior light circuit
  8. Aftershock77

    Aftershock77 New Member

    As I said before I was doing other projects as well. So I disconnected for another job. Volt meter was at 14, figured its a relay gone bad.
  9. sstoner911

    sstoner911 Epic Member 5+ Years 1000 Posts

    I would have the alternator tested to see if its charging. The only thing you did that was odd, was disconnect the negative battery terminal. So if nothing is wrong there, you may have a problem hat has reared its ugly head at the time you did your oil change.

    Have you installed anything electrical lately? Something may be leaving an open circuit draining the battery.
  10. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    does it have lighted mirrors on the sun visors? I have heard of those staying on and draining the battery

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