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Help! Electrical Problems still!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by kpanza, Dec 10, 2001.

  1. kpanza

    kpanza 1/2 ton status

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    Hope some of you can help me here:

    Ok, as of a few weeks ago, my truck's electrical system has been very weird! What is does is this - the lights (headlights, taillights, interior, dash - all of them) dim very quickly down to almost off, then come back on, then dim, back and forth...then they will be fine for a few minutes and then wham - they start dimming all over again! Now, when this happens, I notice the Volt Meter gauge going back and forth, as well as the oil pressure gauge going nuts. Now that I'm watching my gauges more than the road (yikes!), I also notice that before this happens, the volt meter usually goes into an "overcharge" mode - like up to the 15 volts mark or so, then the sh$t starts up! Haven't had any dead batteries or anything else weird. It starts up just perfect, even runs perfect, just the whole electrical system seems to drop down to nothing repeatedly...I have a Red Top Optima and a Powermaster 140 amp alternator, both less than a year old.

    I have checked all the ground straps (body to frame, frame to block, battery to body, etc) they are all good. Anyone know what could be causing the alternator to go into overcharge mode then have all these sudden drops? Is it the alternator?? Should I have it tested? Whoever helps me here will get some SERIOUS discounts on parts!! ha,ha Man, I HATE electrical!!!! [​IMG] Sorry for the length...
     
  2. shaggyk5

    shaggyk5 1/2 ton status

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    any parts store should be able to check your charging system for free, we do it here at my work for anyone who wants it. It cant hurt to see what the thing says, especially if its free. As far as actually diagnosing the problem, i have no clue. [​IMG]

    -matt
    <font color=blue>86, 350, 35"TSL's</font color=blue><font color=red>Lop Sop Doi Off-Road</font color=red>
    www.chevyhedk5.tripod.com
     
  3. kpanza

    kpanza 1/2 ton status

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    Yeah, that's what I figured - there is one guy down at the local Kragen that I trust, I will see if he can hook it up and see what it says...

    If this is a short of some kind, what system would cause such a large voltage drop?? My gut says it is headlights, but that's just cause I notice the lights flicker at night...I have seen the volt meter do this plenty recently in the daytime with no lights on at all (just see the meter going crazy in the daytime).
     
  4. 71RestoRod

    71RestoRod 1/2 ton status

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    Obviously a guess, but it sounds like a bad headlight switch to me.
     
  5. HarryH3

    HarryH3 1 ton status Author

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    Even if the alternator is failing, the battery can keep the lights on for a few hours. I'd run some wires directly to the battery and route them inside to a voltage meter, and see if it tells you the same thing that you're seeing on the dash meter. If the lights all go dim, but the meter connected directly to the battery still reads OK, then you have to start looking for a bad connection or failing component.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  6. Twiz

    Twiz 1/2 ton status

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    nStill sounds like a bad ground problem to me.
    Grounds are linked to a single point and branch out to groups. Like this: Battery ground to block, block to frame/body, .. from there they group out, like the tail lights (commonly) use a single ground, intirior lights use the same ground, ECM and sensors use the same ground, instermant-panels use the same ground. So checking the main grounds was only part of the proces, you need to keep looking.

    With electrical faults, it helps to trace the current flow from one end to the other. A group of componets going "out" intermitantly would indicate a intermitant ground fault, like a frayed wire, corrosion, or a loose grounding bolt or strap. So I would check the power flow in reverse, starting at the ground and work your way to the power. Try to find a wireing diagram nd find the common ground. It -could- be something else, but it is a process of eliminatoin. You need to make sure the cannections are secure first the go on to the next step.

    <font color=blue>Twiz</font color=blue>
    Can't get it up?
    So, drop it in
    gear.
     
  7. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    You just described how my alternator died on my trip to Texas. I didn't really get a flickering though, but my lights would steadily get brighter until the volt guage was reading over 16 volts and then stay that way for a few minutes. Then it would drop back down to 13.5-14 volts and be normal for a while. It did this to me starting in Kansas and the alternator finally quit altogether near Waco, TX.

    If you have an old known working alternator try swapping it in and see if it acts the same...

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
    <a target="_blank" href=http://coloradok5.com/gallery/project_T2> tRusty pics...</a>
     
  8. k5ntexas

    k5ntexas 1/2 ton status

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    the same thing happened to my friend not too long ago and like trusty said. it was the alternator for him. just try to see if another alternator works. if it don't do it then its yer alternator. hope this helps. later.

    jacob

    what is that low rider doing under my k5?
    wow nice lil jap car. whats it good for?
     
  9. Skigirl

    Skigirl 1/2 ton status

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    I think it's a charging problem, but may or may not be the alternator -
    1. check the drive belt and make sure it's not loose.

    2.Make sure the alternator mounting bolts are tight.

    3. Make sure the battery is fully charged and in good shape as one bad cell can cause an alternator to overcharge.

    Then try this:

    Disconnect the negative battery cable. With the key off, connect a test light between the negative battery post and the disconnected clamp. If the test light comes on, there's a short in the system. Disconnect the alternator wiring harness. If the light goes out, the problem is the alternator, and it should be replaced. If the light stays on, start pulling the fuses one by one until the light goes out. That will tell you which component is shorting.

    If, when you test the battery to ground connection and the test light doesn't come on, re-connect the negative battery cable and check the voltage with the engine off. It should be normal.

    Then start the engine, rev it to about 2000RPM and recheck voltage, it should be just under 15. Turn the headlights on. The voltage should drop a little then come back up if the charging system is OK. If voltage is reading more than 15 volts, and you have an external regulator, check the regulator ground connection. If that's OK, the problem is either the regulator, alternator or wiring between them. If you have an internal regualtor, replace the alternator.

    That's all I know to do. Hope it helps.
     
  10. chevyracing

    chevyracing 1/2 ton status

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    I am clueless on this one so I will just stick with my default answer........Put a big block in it.

    John

    Like to go sloppin' 'round in da mud in a rapid fashion....=)

    <a target="_blank" href=http://coloradok5.com/gallery/albun31?&page=1>BLAZER PICS</a>
     
  11. californiak5

    californiak5 1/2 ton status

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    I like Skigirls answer, so I will just 2nd that one. [​IMG] I was thinking regulator when I first read your post, but it wouldn't hurt to try what Pam said to try and locate the problem. Good luck Bro.

    See Ya,
    Keith

    <font color=green>Born to Drive My K5</font color=green>

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  12. Executioner

    Executioner 1/2 ton status

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    Check the Alternator out on a scope, its either a diode or two gone bad, or the voltage regukator inside the alt.
    Also could be the wiring for the alt. voltage feedback, or the ignition switch, if you don't have the one wire option
    on that Powermaster.
    Good luck, and let us know when you find the major cause.
     
  13. kpanza

    kpanza 1/2 ton status

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    Thanks everyone! I appreciate all the help, I would think that I could probably find the problem now with all of this info! [​IMG] I will update you with whatever progress I make!

    Pam, that sounds like you know your electrical! And I see you are in LA, maybe you can join us on our next So Cal wheeling trip?
     
  14. RaisedK5

    RaisedK5 1/2 ton status

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    Ya, cause when we go wheelin' we have fun like it was on sale for $19.95. The more the merrier. So is it going to be Big Bear on New Years? I'll have to see if i can get off work. And maybe get the doubler in by then, ooops did i let the cat out of the bag?? Yep, by the next trip i should have a whole new suspension, and the doubler. Woo hoo!

    Leland aka RaisedK5

    "Of all the things I've lost, I think I miss my mind the most!"
    "Are the voices in my head bothering you?
     
  15. kpanza

    kpanza 1/2 ton status

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    You sumb*tch!! [​IMG] Really, a doubler?? Cool...sh*t, I better get the ol' credit cards dusted off so that I can keep up with you and Esteban!! [​IMG] Hmmm, Dana 60, Klune-V case (to get my 155:1 gearing) and those 38s are gonna look good on the AMEX Platinum! ha,ha

    Leland, let me know if you need any help, I will come over and help drink your beer! ha,ha

    Oh, and yeah, if nothing else comes up, i will probably just go up to the cabin near Big Bear for New Years...I'll keep you posted...
     
  16. chvyhs

    chvyhs 1/2 ton status

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    I have an altenator you can borrow. Just let me know if you want it.

    <font color=red>Sure your Durango can go any place I can go, (if I hook a strap to it).</font color=red>
     
  17. kpanza

    kpanza 1/2 ton status

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    I actually have another alternator that is still good, so I will try that if it comes to being the alternator! But thanks for the offer, I appreciate it!
     
  18. RaisedK5

    RaisedK5 1/2 ton status

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    You could loan me a driveway if you want to, my neighbors get a little pissed when i start playing with the blazer in the parking lot at the condo, maybe it was all that mud i left there after Truckhaven, hmmm oh well, actually i'll probably be doing it all over the New Years Weekend, The new suspension is supposed to come in right after Christmas. yay! We can still drink beer though. MMMmmm beer! Necter of the Gods. Like Liquid bread, only its hard to get a piece of ham between two Beers.

    Leland aka RaisedK5

    "Of all the things I've lost, I think I miss my mind the most!"
    "Are the voices in my head bothering you?
     
  19. Skigirl

    Skigirl 1/2 ton status

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    Keith,

    Thanks for the invite. Never been wheeling, but once I get the truck done, I'm willing to put a tire in and test the ... whatever.

    Bought the rig mainly a ski truck for me. And guess it's time to post something about a K5 ski trip to Tahoe, maybe after the holidays.

    Actually electrical is about all I know about trucks, and I'm still learning a lot. It's annoyingly tedious, but I kind of understand the basics.

    Hoping to have my rig ready to do anything except sit in my driveway by Jan 1st, but I suspect it'll be in the body shop about then.
     
  20. kpanza

    kpanza 1/2 ton status

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    Pam,

    Sure thing! You should come out with us, we really have a lot of fun out there on the trails! Yeah, I personally HATE electrical, it really annoys me! ha,ha [​IMG] That's probably why my truck looks like a scrapyard of electrical wires! ha,ha,ha

    I am hoping to maybe go skiing over New Years locally, hopefully we get enough snow by then to make it decent! I also want to go to Mammoth, they are getting snow by the boatload!! Base of 6-7 feet already! And I have a friend who lives about an hour and a half from Tahoe, am gonna try to go up and see him and his wife this winter for some skiing also! Maybe we will get a wheeling/skiing trip going this winter?? Sounds like a good idea to me!
     

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