rocketwheels Posted February 12, 2016 Share Posted February 12, 2016 ....long story short, after loosing a battery to what seemed to be an 8 year old Alternator that went bad, I've gone thru 2 new units off the shelf that would not charge and said "regulator no output" on the portable test unit hooked to the truck. We bench tested the 2nd new alternator and it tested good on output. SO.... I bought a pigtail for the harness, but before I chopped off the old one, I tested the 2 wires leading from it....the yellow lead went up to the "control center" area under the hood between the battery and the expansion tank and plugged into a single junction before diving into the big wire harness....and the brown went to a flat multi-wire junction up near the battery. Each of these tested solid with an Ohm meter from the pigtail to each of these junctions. The large "red" lead to the relay (not part of the pigtail) also tested solid. Is there something I'm missing, like perhaps the regulator isn't internal on these alternators....but built into the works of the truck? Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 12, 2016 Share Posted February 12, 2016 Your Renix has the Delco CS-130 alternator which is internally regulated. Link to comment Share on other sites More sharing options...
rocketwheels Posted February 12, 2016 Author Share Posted February 12, 2016 ...after cleaning , testing continuity and re-installing the alternator and said wires, it still test as "regulator bad". I'm flummoxed. Word for the day ! "Flummoxed" .... guess it is better to be labelled "Flummoxed" than "arsonist", 'cause thats what the next word of the day will be if I can't figure this pile-o-crap out ! Link to comment Share on other sites More sharing options...
rocketwheels Posted February 12, 2016 Author Share Posted February 12, 2016 Thanks, Hornbrod, that is the type I have. Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 12, 2016 Share Posted February 12, 2016 Try running an additional ground wire (min 10 AWG) from an alt case bolt or threaded case hole directly to the negative battery post. IIRC these things ground only through the mount - not the best. Link to comment Share on other sites More sharing options...
Gene Posted February 12, 2016 Share Posted February 12, 2016 Hi rocket, I'm a little rusty at this, but the alternator should have three wires. One is a heavy red one, which is the alternator output. How ever, on another connector are two smaller wires, which are the inputs to the field and regulator. One of them, which is yellow, should be hot whenever the ignition switch is on. The other one is the weird one. It should be tan with a white tracer. It actually feeds through the ignition switch, and then through the voltmeter or indicator light on the dash, then to the alternator. I know, on GM's of this era with an indicator light, if the indicator light burns out, the alternator will not charge. Something about the indicator light putting resistance in the circuit. According to the wiring diagram, I think the gauge works similarly, putting resistance of the circuit. In any case, with ignition on, you should have full battery voltage at the yellow wire connector, and there should be voltage, less than full battery, at the tan/white wire. If there is no voltage at the tan/white wire, a burned-out indicator bulb, or problem with the voltage gauge, may be the problem. I'm not certain of the above, but I remember this with GM's of this era, and it looks like the Jeep wiring diagram is similar. Good luck! Gene Link to comment Share on other sites More sharing options...
rocketwheels Posted February 12, 2016 Author Share Posted February 12, 2016 Gene....thank you, this is interesting. You nailed the description of the wires .The dash light (mine has a light, no gauge) has not come on lately that I can remember. Shouldn't it always come on when the ignition is on but the truck is not running? If so, then the bulb has gone out or something to this effect. I'll get the volt meter and see where this takes me. Thanks again !! Link to comment Share on other sites More sharing options...
rocketwheels Posted February 12, 2016 Author Share Posted February 12, 2016 Oh ....if it had only been that simple....with the ignition on, there was 0 current in the brown wire, so I pulled the cluster ....AND.....the bulb is good :hmm: , so.....until it got dark I was stripping back conduit and cloth tape, trying to follow that little brown wire to a junction where i can test it again. Looks like I have something to do tomorrow...... :dunno: Link to comment Share on other sites More sharing options...
rocketwheels Posted February 12, 2016 Author Share Posted February 12, 2016 Gene....is it possible there is a failure in the ignition switch since the brown wire goes from there to the light and then out to the alternator? Should there be current on at least one side of the circuit board the bulb plugs into? If not then I need to pull the ignition switch and check there.....I dunno, this is confusing since I don't have a grasp of the whole system from start to finish . Link to comment Share on other sites More sharing options...
Gene Posted February 13, 2016 Share Posted February 13, 2016 Hi rocket, You are right, there should be voltage at the indicator light socket. There is a wiring diagram in here http://www.bteventures.com//mj1988electricalmanual.pdf page 25 There is a fuse in the circuit too. I doubt it is the ignition switch itself, if all the other "ignition on" accessories work. You're close, keep digging! Gene Link to comment Share on other sites More sharing options...
rocketwheels Posted February 13, 2016 Author Share Posted February 13, 2016 Gene, on page 25 the tan w/tr wire is labeled as jumper to ground in the "trouble shooting at dash light / gauge". I haven't checked the fuse for the " instr panel" yet (it's 20 degrees outside this morn) , but if it is OK , could I get the same result by side splitting the pigtail at the alternator and grounding to the battery? Hornbrod also suggested the alternator case doesn't ground well, I assume this is 2 different types of ground , but it couldn't hurt...? Link to comment Share on other sites More sharing options...
Gene Posted February 13, 2016 Share Posted February 13, 2016 Hi rocket, I'm a little uncomfortable posting this. Normally I like to post stuff that I am reasonably sure about. I'm not as sure about this, much of this is from memory from about 15 years ago, but here goes. For reasons which are totally unclear to me, GM set the alternator up so their are two wires bringing voltage in, to the regulator and field, and one wire bringing voltage out to the electrical system. One of the wires coming in, the yellow, should be hot anytime the ignition is on. How ever, the tan/white wire has to have a 10 ohm resistance in place, before it brings hot to the alternator. The indicator light bulb serves this purpose. So, basically, voltage goes from the ignition switch, through the fuse, through the indicator light, and then down to the alternator. If this fuse is blown, or the light bulb is burned out, then no voltage comes down this wire. The alternator field will not get current, and the alternator will not produce electricity. The test you're referring to, which is very confusing, just wants you to ground the wire going down to the alternator. When you ground that, for test purposes, the circuit then becomes ignition switch to fuse to indicator lights to ground. So then the indicator light should light. If you try this test, and the indicator light does not light, then the fuse is blown, the indicator light is burned out, or there's a problem with the wiring. Now, if you're just in an "I want to get this up and going" situation, I think you can take any source of current which is hot with the ignition on (such as the yellow wire), and connect a new wire to this. Get a 10 ohm resistor, solder this to the new wire, and then connect this where the tan/white wire would go. So current source to 10 ohm resistor to tan/white wire's terminal on alternator. This would disable the indicator light or gauge, but would get the alternator producing current again. As I said, I'm not certain of the above. Good luck! Gene Link to comment Share on other sites More sharing options...
rocketwheels Posted February 13, 2016 Author Share Posted February 13, 2016 Ok, so it is not a ground in its intention. I won't make that mistake. I may try the test to see if the light lights up to check the wiring. I checked and the fuse is good and there is (I'm stupid and don't understand why) there is 12v on both sides of the "batt" light on the circuit board on the back of the cluster when the ignition switch is turned on.... wouldn't that make the light burn if it is good? I swapped a bulb in from the temp light and still no burn. I may have to try that trick you mentioned, sounds like a plan. Thanks for your insight and help Link to comment Share on other sites More sharing options...
Gene Posted February 13, 2016 Share Posted February 13, 2016 That question shows that you "get it!" If the alternator is working properly, you have about 12 V on one side of the bulb, and about 12 V on the other side of the bulb. Since that is equal, no current will flow through the bulb. If the alternator is not working, then there will still be 12 V at the ignition switch side of the bulb, but there will be no voltage at the alternator side of the bulb. (Somehow, in that situation, this terminal becomes grounded at the alternator. I'm just accepting this, I don't really understand it.) So, if the alternator is not producing electricity, then current flows from 12 V on one side of the bulb, to ground that the other side. The above is why I had some reluctance posting. This sounds so goofy it doesn't make sense. Gene Link to comment Share on other sites More sharing options...
rocketwheels Posted February 13, 2016 Author Share Posted February 13, 2016 I have a habit of thinking all current is "power ...items....ground" , instead or thinking of circuits. Then....that means I have current at the fuse , at the switch , at the bulb and leaving the cluster ....but not in the wire out in the harness. SO....gotta trace down that danged wire from the cluster to the alternator and find out were they "break" or bad junction connection is. BUT FIRST....I'm gonna ground that tan wire to the battery at the end of the pig tail to see if the bulb lights up....and if it does.... WOW, is there no end to this? Link to comment Share on other sites More sharing options...
rocketwheels Posted February 16, 2016 Author Share Posted February 16, 2016 WELL ...... ol' Sgt Rock is producing juice again, thanks to Gene and his "I want to get this up and going" plan. I ground the system out and the Batt light did not burn, and after several days of tracing harnesses and cleaning connectors, it was still a "no go". So ... (lucky I live in Huntsville, where everything is just a few minutes away)... after a trip to Radio Shack for the Resistor, and a swing by the local hobby store to borrow a small piece of wire and the soldering iron, I performed said "bypass surgery" on the Alternator Harness Pigtail....then ran down the street to O'Reilys for a quick check with their portable Batt/Alt checker and....VIOLA ! .... output is normal, alt checked good. Now, if I could just get the danged Speedo cable back into place after pulling the cluster out, my big fat hands just don't fit up in and back behind the cluster to re-seat the cable straight. Thanks Gene and Hornbrod !! Link to comment Share on other sites More sharing options...
Gene Posted February 16, 2016 Share Posted February 16, 2016 Way to go rocket! Congrats on the fix! Now buy a voltmeter and soldering iron/gun of your own, for future projects..... Gene Link to comment Share on other sites More sharing options...
ParadiseMJ Posted February 17, 2016 Share Posted February 17, 2016 :popcorn: Similar things going on here, so I'm rapt. Good stuff. _______________________________________________________________________________* Off topic: I can't believe that someone finally got the right spelling and context of the French word "Voila" (there you have it, essentially). I've seen "walla" "Wa-La", "Viol-a", and just about every other butcher job. Link to comment Share on other sites More sharing options...
gogmorgo Posted February 17, 2016 Share Posted February 17, 2016 ... I see "viola". Link to comment Share on other sites More sharing options...
cruiser54 Posted February 17, 2016 Share Posted February 17, 2016 ... I see "viola". An old girlfriend of yours? Link to comment Share on other sites More sharing options...
rocketwheels Posted December 21, 2016 Author Share Posted December 21, 2016 Hey, had an update and more thoughts on this charging issue....the trick Gene had with the 10 amp resistor works, but the resistor has gotten so hot it burned off all the shrink wrap and the wire insualtio close to it. Still works, though. 2nd, i now have a very slow battery drain, maybe caused by this alteration , maybe not....just added a battery disconnect. 3rd , never did find the area were the wire has the issue, but as some of you may remember, my fuse box is totally shot, melted and deformed due to heat generated by the damage caused by brake fluid dripping down the fuse box for no telling how long by the previous owner. That may be were the alt wire connection is having the bad connection. Anyways , Genes "by-pass the ignition/alt light at the alternator" trick works, just be prepared for the heat generated at the connection, and a possible slow battery drain. I guess i will look for another harness with fuse block for a future project! Link to comment Share on other sites More sharing options...
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