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Ammeter drops with turn signals, brake and backup lights... **UPDATE**

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 89GMCSuburban, Jul 5, 2003.

  1. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    When anything goes on, my gage drops to just above the red, but will never go into it. It's doing this every once in a while (Every couple of minutes) and will even cause a power loss to my CD deck where it shuts off then turns back on. Is it my alternator biting the dust?
     
  2. R72K5

    R72K5 Banned

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    Re: Ammeter drops with turn signals, brake and backup lights...

    id have to start with it either being bad connection at alternator or at battery or at guage or broken wire inside insulation somewhere, or alt belt slipping but cant hear it squeal- if it is at all, sometimes they dont make noise when the are slipping.

    if you pseed up the engine will it not do this, or does it do it no matter engnie RPM ? engine always start up with no lag ? what happens if you turn on headlights at idle speed ? does engine slow up any or alternator kick in and make the output noise that you hear from them when you are jump starting another car ? how old is the alternator where is it from ?
     
  3. tecton

    tecton 1/2 ton status

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    Re: Ammeter drops with turn signals, brake and backup lights...

    see if your alt belt is tight
     
  4. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: Ammeter drops with turn signals, brake and backup lights...

    Check your body grounds. There is a ground strap behind the passengerside head to the fire wal. If that strap is off it will cause those symptoms.
     
  5. MTBLAZER89

    MTBLAZER89 3/4 ton status Premium Member GMOTM Winner

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    Re: Ammeter drops with turn signals, brake and backup lights...

    check your voltage regulator too I have seen it cause this problem.
     
  6. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Re: Ammeter drops with turn signals, brake and backup lights...

    The more I hit the gas, the lower the gage goes. Idle speed is lower than usual. It does the voltage drop in bursts. Headlights don't drop it too much. I hear a struggling noise sometimes. It's about a year old and it's a lifetime warranty one from O'Reilly.
    Worse yet, the thing just died and I had to get it towed home. The gage was going low again, so I turnedd off all acc. to try and get home. I take a right turn, as I'm taking it, the fasten belts light comes on and the power steering goes away. The engine almost dies taking the turn. I go a little ways further and take another right turn. As I do that, my ammeter drops to nothing and the engine dies. As I pull over to the side of the road, my caution lights don't turn on. The bizarre part??? My interior lights work, my headlights work, nothing else does. The alarm was cutting in and out like it would get power, then go away and this would happen in evenly spaced intervals. What the heck is wrong with it??!??! It won't start and is sitting in the driveway with the windows rolled down (power) and it's supposed to rain for the next week. I'm going to take it to the shop Monday since no one could work on it tomorrow. Any ideas of what I should look at tomorrow?

    P.S. About a month ago, I noticed when I'd turn the key to engage the starter, it would pause sometimes for half a second or so before it would crank. It always starts quickly once it cranks. It would do this rarely, but it would happen.
     
  7. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Re: Ammeter drops with turn signals, brake and backup lights...

    Ground strap is good. Had the engine out in January and checked its condition and made sure I had it on, but I'll re-check. Alternator belt slipping would be tough, it's a serpentine belt with auto tensioner.
     
  8. Skigirl

    Skigirl 1/2 ton status

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    Re: Ammeter drops with turn signals, brake and backup lights...

    Sounds like it's time to get the alternator tested.
     
  9. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Re: Ammeter drops with turn signals, brake and backup lights...

    I'm going to do that, but doesn't it sound like a short? When I turn the key to "on", no lights turn on...no check engine, no seat belt light, nothing. My radio doesn't turn on, my alarm doesn't work, but my headlights and interior lights work like they're fully charged. /forums/images/graemlins/confused.gif I mean, isn't it strange that my headlights work and my interior lights work, but my hazards don't even turn on to start blinking?
     
  10. crazykev4x4

    crazykev4x4 1/2 ton status

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    Re: Ammeter drops with turn signals, brake and backup lights...

    does the engine start ? maybe u havea burned fusible link somewhere under the hood . id start checking some wiring and stuff . also did u check your ignition switch . It is on the top of the steering column by the firewall . The switch can go bad and melt the connector sometimes . i would check that

    Kevin /forums/images/graemlins/k5.gif
     
  11. Skigirl

    Skigirl 1/2 ton status

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    Re: Ammeter drops with turn signals, brake and backup lights...

    That sounds like 2 different problems to me. One, the alternaotr and 2) something open or shorted in the circuit you mention.

    Shorts I've had (including stuff that drains the battery) haven't caused the ammeter gauge to drop like you described earlier. I've seen it drop when power is being drained beyond the capacity of the alternator to recharge or spike when the regulator goes out.

    If you are having a short somewhere that's draining the battery more than the alternator can recharge on short, low speed trips, then you could check that out with an ammeter at the battery and eliminate that possibility.
     
  12. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Re: Ammeter drops with turn signals, brake and backup lights...

    I think it is the ignition switch. If my headlights and interior lights work, those stay on even with the switch in "off" anyway. All the other stuff that isn't working (except the alarm) won't work unless the switch is in "on". With the switch in "on", the stuff still doesn't turn on. Now...how do I test the switch??
     
  13. crazykev4x4

    crazykev4x4 1/2 ton status

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    Re: Ammeter drops with turn signals, brake and backup lights...

    look at the switch . Does it look or smell burnt? u could get a service manual with a wiring diagram and check it out . or try a known good one in the truck u can try it with out mounting it on the column. .

    Kevin /forums/images/graemlins/k5.gif /forums/images/graemlins/usaflag.gif
     
  14. Skigirl

    Skigirl 1/2 ton status

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    Re: Ammeter drops with turn signals, brake and backup lights...

    [ QUOTE ]
    how do I test the switch??

    [/ QUOTE ]

    I don't know if the switch for your year is the same as mine ('76 K5). That said, you could use a test light to see if the switch terminals have current when they are supposed to and don't when they aren't supposed to.

    Here's how the switch works on mine (from the service manual):

    The ignition is fed from a junction at the horn relay to the BAT terminal of the switch. When the igntion is OFF, no current flows thru the switch.

    When the ignition switch is turned to the ACC position, BAT is connected to the ACC terminal.

    When the ignition is trurned to START, the BAT terminal is connected to SOL (solenoid) and IGN terminals.

    When the switch is released from START to RUN, the IGN and ACC terminals are connected to BAT. SOL is not longer connected.

    The instrument panel warning lights are fed from the IGN terminal and have current when in the START and RUN positions.

    So, if you put a test light probe to each terminal on the switch that should have current in the above positions and one of them doesn't when it should, then that part is bad (open). Or if there is current to terminals when there shouldn't be, then there's a short.

    If it were me, I'd just replace it and chaulk one more thing off my list of parts that may go tits up soon /forums/images/graemlins/thumb.gif

    I do have a diagram if you need it.
     
  15. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: Ammeter drops with turn signals, brake and backup lights...

    EVERYTHING gets power from the connection at the starter. Wires could have got against the exhaust or something. There is 3 fusable links at that junction. two more fusable links off the junction block on the fire wall.
    Humor me and check that ground strap again. Head lights ground off the coresupport. everything else grounds off the body.
     
  16. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Re: Ammeter drops with turn signals, brake and backup lights...

    Took it to a shop today...I don't have enough to fiddle with it. /forums/images/graemlins/smirk.gif They called me and said they need another day, they still can't figure it out. Will let you all know when I find out...
     
  17. OFFRDK5

    OFFRDK5 1/2 ton status Premium Member

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    Re: Ammeter drops with turn signals, brake and backup lights...

    Did you find out what your problem is?
     
  18. Ignato

    Ignato Registered Member

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    Re: Ammeter drops with turn signals, brake and backup lights...

    OMG DUDE!!! I had almost the exact same problem!!

    I think what it was, was the starter(solinoid) grounding out on the heat shield. I was out in the smack dab middle of the frickin desert. I go to start it, and the alarm starts freakin out, only certain electrical iteams work, and the starter is freakin out.
    I first thought it was the alarm system, but I had a buddy that worked at circuit city, he totally disconnected the alarm. It SOUNDED ok, but it wouldn't start. So we popped some jumper cables on the battery, and it somehow backfed thru the cables and MELTED them. They were some pretty heavy duty cables too. I still have the burn marks on the Blazer.
    So anyways, I work my way around the the starter, take it off, and the solinoid smells burnt. I replace the sucker, and everything works great! I also needed a new battery. Autozone said it coundn't be recharched.

    I've now wrapped my heat shield is some heat reflective tape. (that does NOT conduct electricity) /forums/images/graemlins/crazy.gif
     
  19. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Re: Ammeter drops with turn signals, brake and backup lights...

    Fusible link off the starter. Grounded to a post on the starter and blew.
     
  20. Ignato

    Ignato Registered Member

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    Re: Ammeter drops with turn signals, brake and backup lights...

    AH-HA! So it WAS the same problem....sorta! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
    Sure glad you got it solved!
     

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