djmikemouse Posted July 11, 2015 Report Share Posted July 11, 2015 About a week ago my '85 720 started making an odd kind of light grinding noise coming from under the passenger side of the dash and the battery light started glowing and got brighter as the rpms went up. A friend suggested taking apart the blower, cleaning it and checking for loose wires, we cleaned everything and put it back (we did some thing wrong cause now the highest fan speed works) with no resolve to the issue. It almost always starts when my truck starts and the noise will come on and off but the battery light is constant for the most part. Any insight is greatly apreciated tank you! Quote Link to comment
datzenmike Posted July 11, 2015 Report Share Posted July 11, 2015 The sound you hear is the auto choke relay not the heater. The rlay is up under the pass side dash on the kick pad above the speaker. Just touch it and you can feel it buzzing. It needs a charging alternator signal to work properly and when the alternator is failing or for whatever reason has a poor charge, the relay clicks on and off rapidly and makes a buzzing noise. You may have noticed a faster idle and a decrease in mileage also. This is because the choke is not being electrically heated and is partly on at all times. Measure the voltage across the battery posts while running. It should be over 14 volts. Check fan belt. Check the plug in the rear of the alternator for secure fit and no loose wires. Clean battery terminals and eliminate everything as a possible charging system failure. Probably it is the alternator If you have the original alternator I suggest you NOT trade it in for the pieces of crap passed off today as 're-manufactured' and having a truly useless 'life time warranty'. By useless, I mean it leaves you stranded for the 4th time and a $100 tow bill, but you get a 5th, 'free' replacement alternator that you have to put in. Instead, replace the brushes. You used to be able to get them as a kit for under $10. 2 Quote Link to comment
Ed-datsun521 Posted July 12, 2015 Report Share Posted July 12, 2015 Dam mike that answer was perfect and in only 15 min The Datsun wisperer ! 1 Quote Link to comment
djmikemouse Posted July 12, 2015 Author Report Share Posted July 12, 2015 That answer was perfect Mike! I switched out the alternator and good as new! Now I need to figure out what I did while cleaning the blower to loose the first 3 speed settings haha! Thank you! Quote Link to comment
datzenmike Posted July 12, 2015 Report Share Posted July 12, 2015 Power from the fuse box goes directly to the blower motor. from there the switch selects several paths to ground through varying resistances to select different speeds. High speed by passes any resistance and is directly to ground. These 'resistances' are located in the fan housing in the air stream from the blower fan to keep them cool. The are located upper front left side of the blower. The picture of mine is with the blower out of the vehicle so is likely upside down. Just look for the plug with all the blue wires... Quote Link to comment
djmikemouse Posted July 12, 2015 Author Report Share Posted July 12, 2015 Perfect! Thanks Mike! Quote Link to comment
djmikemouse Posted July 25, 2015 Author Report Share Posted July 25, 2015 Yes it was unplugged! But now the alternator relay makes an awful ticking noise and the battery light is still flashing. It didn't start happening until a few days after I put in the new alternator. Any suggestions? Quote Link to comment
datzenmike Posted July 25, 2015 Report Share Posted July 25, 2015 When something happens, always think back on thew last thing you did. For example The alternator was replaced ..........and now the charge light is on. It would seem like the 'new' alternator is what we call 'bad in the box' OR something was altered, damaged or unplugged while changing it. Have to ask though, why was it replaced? BTW the clicking noise is the choke heater relay located just above the heater fan on the pass side kick panel. It requires a charging alternator to work properly or the low voltage causes it to turn on off on off very quickly and make a buzzing sound. Quote Link to comment
djmikemouse Posted July 25, 2015 Author Report Share Posted July 25, 2015 Well I had the alternator tested at an auto parts store and the guy told me it was bad. I'm thinking he just told me that so I would buy a new one now... Quote Link to comment
datzenmike Posted July 25, 2015 Report Share Posted July 25, 2015 Your old one should have a warranty. Take it back. Usually those $60 Bosch or Orylie's, Lordco, Pep Boys have a useless lifetime warranty. Not much fun taking it back for the 4th time after being towed home for your 'free replacement' alternator. 1 Quote Link to comment
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