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Electrical Problems

Discussion in 'Chevy Trucks' started by Dave_Dean, Dec 15, 2002.

  1. Dave_Dean

    Dave_Dean Junior Member
    Messages: 28

    83 K5 Blazer 350 4x4 used extensively off road. When I have the headlights, wipers, and the defroster turned on to high the voltage meter reads about 8.5. If I turn the defroster fan off the volt meter will slowly come back up to 14. Even if the wipers are off the meter goes low. The alternator is only 1 maybe 2 years old. I've checked/cleaned the connections on the alternator and battery which were not bad but I cleaned them anyways. Battery cables are in good shape with no corrosion. I even added an extra ground strap from the battery to the cab. I don't know much about electrical stuff but with the blower motor being almost 20 years old could it be going bad and would it cause the drain on the alternator? The fan is still responsive to the switch changes between speeds and still blows a good amount of air. It only does it when the fan is turned up to med-hi and hi. Also the wipers go slow occasionaly. The wipers have no effect on the volt meter unless the blower motor is on as well. Once again any help would be greatly appreciated.
     
  2. Mike 97 SS

    Mike 97 SS Banned
    from U.S.A.
    Messages: 1,106

    Well first off, i wouldnt pay to much attention to factory dashboard gauges cause it seems as they get old, they tend not to work 100% anymore. Next when you say the alternator is 1-2 years old, im assuming it was purchased as a rebuilt? Your lucky you got that much use out of a rebuilt in my oppinion. I have seen rebuilts be bad right out the box and in other cases last a week or 2 then quit. First thing i would do is have someone or a shop put a real meter on the battery while its running to check the charging rate if you have not yet. That is the better way to check rather than judge by the dashboard gauge. See what they come up with, if they also say its coming up low, i think your alternator is on the way out. Is the voltage regulator built in on yours or is it separate? The more stuff you turn on the harder the alternator has to work and it seems these rebuilts from parts stores dont like to work as it is. :) Oh one last thing, make sure your alternator belt is tight and not slipping, just thought of that. Mike
     
  3. JohnnyU

    JohnnyU 2000 Club Member
    Messages: 2,040

    Judging by that I'd say the next thing to check would be teh blower motor, seems to me there is a bad connection or dirty/worn brushes what are causing a high current draw, for $30 it might be worth replacing.
     
  4. Dave_Dean

    Dave_Dean Junior Member
    Messages: 28

    Thanks

    Yea the alternator is a rebuild. Good thing it came with a lifetime warranty. I've put a digital multi-reader in line between the positive cable and the positive post and am getting a good charge. (while accessories are off) I think I'll change out the blower motor. 20 years is a long time to expect it to work efficiently. By chance would anybody know what the amp draw should be for a properly running fan? While I'm at it the wiper motor will get changed as well.
     
  5. Mike 97 SS

    Mike 97 SS Banned
    from U.S.A.
    Messages: 1,106

    I wouldnt change either of the things you mentioned. If its lifetime warranty go get yourself another one and give that a shot first. If they will give you another one for free, why not try that route first? You tried checking the charging rate with everything turned off, why not try it with everyting turned on? Thats even a better test. The alternator should still be able to charge with everything pulling juice. I wouldnt go changing parts to try and eliminate the problem. Mike
     
  6. Garagekeeper

    Garagekeeper Senior Member
    Messages: 459

    Dont't Change Anything

    Have some one do a battery and alternator test on the truck before you change anything. This will tell you what the battery capacity is along with the output in amps of your alternator, and what the current draw is from your fan and wipers etc. You may just have a battery that's going bad. I may cost you a few bucks to have it checked out but will save you in the long run. :rolleyes: John
     
  7. Dave_Dean

    Dave_Dean Junior Member
    Messages: 28

    Last edited: Dec 16, 2002
  8. Mike 97 SS

    Mike 97 SS Banned
    from U.S.A.
    Messages: 1,106

    So did you fix it or what? Mike
     
  9. Dave_Dean

    Dave_Dean Junior Member
    Messages: 28

    Not yet. It works as long as I don't have all the accessories on so it is low on the priority list. Lower ball joints, rear axle seals and bearings will come first. This week end and next will be very busy. :)
     
  10. Mike 97 SS

    Mike 97 SS Banned
    from U.S.A.
    Messages: 1,106

    Ahh lower ball joints, fun fun fun. :D Mike
     
  11. Dave_Dean

    Dave_Dean Junior Member
    Messages: 28

    Ball joint replacement

    Well, where to begin. Replacing the ball joint was easy enough. Went to Harbor Freight Tools and picked up the ball joint tool for $30.00. Good deal. Thanks again Alan for the sequence info. Well, in the process I found that the u-joints on both front axles were bad (ball joint tool came in handy here as well) so I replaced them while I was in there, as well as the spindle bearings and seals. Also installed a "Lincoln Locker" in the front. Because of the "Locker" I had to install manual hubs to help keep things under control so to speak. While in the sh*t both will be locked but if just trail cruising only one will get locked.

    Time to do the rear axle seals and bearings and I find that the spider, side gears and carrier bearings were shot. I am amazed that it has held up this long. The damage was pretty bad. Bearings and seals went in easy enough and once again I broke out the welder to install another "Locker". Am supposed to go wheeling next week so I'll post an update on how things hold up.

    Also installed a dual front shock kit and dual steering stabilizers. Cant wait to finally test it all. Just hope that the breakage gremlin stays away.
     
  12. DarinRay

    DarinRay Junior Member
    Messages: 20

    Well I have a 91 GMC 2500 350 etc...I have been having trouble with the battery voltage for some time now and can't seem to find out what the problem is. I have a new alternator, battery, serpintine (sp?) belt, and I get readings of 14.4 off the alternator and off the batteries (dual). If I put the blower motor on or headlights this reading goes to about 14.0 or near. NOW if I take a volt meter and take readings off my fuse panel near the drivers door I get the loooooowwww readings. 11.8 to 12.5 which is what the cab volt meter reads. The readings off the firewall mounted junction block I get almost the same as the alternator give or take .1 or.2>>>I guess my real question is where does the wire come from and go to that feeds the gauge panel. Does it come off the alternator (little brown wire) or does it go from the starter to the ingnition switch???? I must have some kind of bad wire somewhere between the firewall junction block and the gauge panel. I believe this is the same trouble the you are experiencing too. Well hope we get somewhere with this. ha,ha. Thanks

    Darin
     
  13. Dave_Dean

    Dave_Dean Junior Member
    Messages: 28

    Alternator Test

    Stoped in to Advance Auto and had the alternator tested today. They hooked up the machine and started the motor. After the test he told me that it was fine. Even under load it was putting out 12.7V and 178 amps. I said cool but that is a little strange, it is only rated for something like 70 amps. His reply was "oh". So I get to take it out and turn it in for a "new" one as it was still under warranty. I'll take the new one but I still have a question for anyone here. If it was putting out 178 amps and 12.7V why would the gauge and accessories act like they weren't getting enough juice? I asked them the same question but they couldn't give me an answer.
     
  14. DarinRay

    DarinRay Junior Member
    Messages: 20

    Man I always thought that the alternator had to put out at least 14.0 or better to be in good operating condition. You said you did get the new one though right? If you did then you have nothing to worry about because your new one will probably be fine. Now just because your battery and your alternator say a certain voltage doesn't mean that you will have that same number at your gauges. I mean if you have a bad wire then you plain ole can't have the same. Right? I am trying to find out which wire feeds teh gauges now anyway but nobody has jumped on it yet. I was thinking that my problem and maybe yours too could be in the ingintion swithc if thats where our feeder is for the guages. I have good readings at my batteries and the alternator but have low at the gauges and fuse panels. Jus tlike you I think.

    Darin
     
  15. Dave_Dean

    Dave_Dean Junior Member
    Messages: 28

    Electrical Diagrams

    Here is a link to an on line library by Chiltons. Follow along and enter your trucks info and it will take you to the appropriate diagrams.

    Your truck is a little newer than mine and I'm not sure if the instrument panel wiring is even slightly similar to mine. Chances are that it is not. I put the new alternator in and turned on all the accessories, the gauge fluctuated slightly but didn't drop below 13. We'll see how long this one lasts. With a lifetime warranty I couldn't ask for anything better than a 10 minute swap. When (if) the gauge starts to drop below 13 again I'll know that it is time to get another one.
     
  16. DarinRay

    DarinRay Junior Member
    Messages: 20

    Dave,

    I am sure they are not similar in looks but it's got to get it's feed from somewhere after the alternator and the battery. You know what I mean. A battery without a charger on it shoudl read well above 12.4 vdc if it's a fully functional battery. I had a chart that said a new fully battery is somewhere around 12.75 vdc, 50% batter is 12.4 or something. So my point is with the electric load and also having to charge your battery the voltage has to be more like 14vdc right?? Well check out this site anyway for a better description http://www.tractorbynet.com/cgi-bin...=yanmar&Number=218472&page=&view=&sb=&o=&vc=1
     
  17. Dave_Dean

    Dave_Dean Junior Member
    Messages: 28

    gauge fead

    According the the diagram for my truck the gauge is fed by a brown wire coming off the alternator. I've had my dash completely apart and the gauge/spedo cluster is a whole other world all together. There is a stamped paper thin piece of plastic on the back that has various copper "trails" that take the electrical signals to the appropriate gauges. The next time I have it apart I am going to look and see if there is actually a brown wire that goes to the plug in the back of this. I don't know if the wire goes straight from the starter or through a junction box but I guess a color is a start.
     
    Last edited: Dec 30, 2002
  18. DarinRay

    DarinRay Junior Member
    Messages: 20

    Yeah thats the same color my drawing shows is the brown wire but haven't been able to find that darn wire after the firewall it disappears behind everything by the gas and brake pedal. Man it's sure is a pain in the butt. I mean mine is getting to the point where the draw in the gauges get low enough that the truck starts to run like it stalled with a NO throttle response for a bit. It must be corresponding with the looooowww voltage somewhere but can't quite get my finger on it. ha,ha. Well I hope someone else here or yourself can tell me how this would affect the throttle and the inside guage panel voltage. Talk later

    Darin
     
  19. mulchmonkey2000

    mulchmonkey2000 Senior Member
    Messages: 106

    hey guys, thought i'ld try to post here before starting a new thread. I have a problem with the other wire coming off the altenator. I tested the brown wire and it read somewhere around 12 volts. (book said over 10 is good) I then tested the other wire which says it goes between the altenator and the starter and got no reading. THe book says it is the red wire, but mine is white. The only red wire is the one that goes to the battery. Im' not sure if im missing something or they just swapped wire colors. If there is a short somewhere between the altenator and the starter, would that be the reason that every once in a while when i turn the key i get a click and then a couple tries later it cranks over? I replaced the started on christmas eve so unless something is burning it out i'm pretty sure it isn't that. Do you guys have any idea??? :confused: :confused: :confused:
     
  20. DarinRay

    DarinRay Junior Member
    Messages: 20

    The brown wire comes from the gauge panel off the voltage meter I believe which is needed by the alternator and mine is actually 11.8 or something like that. Now the white wire is something I'm not familiar with because mine is red and fromthe alternator it goes to the firewall junction box on the passenger side. From there there is a wire that feeds that whole block from the battery I think and then off that same box the starter wire or it goes from the battery to the starter and then the junction box. Man I don't really know for sure sorry. The best thing for you to do is follow the wires and find out where they do go...WHich is something I also need to do real soon. You may have a bad wire that is causing the intermediate problems like maybe a fusable link. Well let us know what yo ufind but you should have power at that white wire if that goes to you alternator.

    Darin