Ron240zxt Posted August 5, 2001 Share Posted August 5, 2001 Hello all, just curious how you would connect a 10si altenator to your existing z car wiring. My altinator is out of a late Chevy something. It has 12v, Ground, F, R, On the back of the unit. I figured 12v battery positive, Ground is a given just have it drag on the ground..J/k ® reference isnt this the one that goes to a 12volt switch that tells the altenator to charge. And (f) I have no idea any help or correction please respond.. Thank you ROn Quote Link to comment Share on other sites More sharing options...
Mike C Posted August 5, 2001 Share Posted August 5, 2001 Check out this FAQ from an Oldsmobile board. It talks about converting GM external alternators to internal, but should explain connections.Olds Alternator FAQ Quote Link to comment Share on other sites More sharing options...
blueovalz Posted September 27, 2001 Share Posted September 27, 2001 I've been unable to post a new topic for several days (takes the completed form but never posts it up on the forums board) so I'm riding the coat tail of this one. My problem: the gentleman that rebuilt a GM 3 wire alternator for me insists that the idiot light wire MUST be hooked up to a light. If I just go to ground with it, he says the regulator will burn up, and if I leave it open (no light), he says it will not charge. My questions: what size (wattage) bulb is required. If I go too large it may look like a ground, and if I go too small, it make look like an open to the regulator? Has anybody just used a resistor? And lastly, is his information correct?. Oh yes, I did check out the "Olds FAQ" reference, but it did not address this problem. I hope this reply will work. Quote Link to comment Share on other sites More sharing options...
fastzcars Posted September 27, 2001 Share Posted September 27, 2001 hi guys, hope this helps. on the 240z the black and white wire comes from the ignition switch to the terminal 1 on the alt, there has to be a diode in that line if you are NOT conecting a 12v lamp.if you are using a lamp, an indacter bulb like a 194 can be used. as long as its NOT a light emitting diode. terminal 2 is a constant 12v,that one you can be connected to the large output post of the alt.terminal 1 is closest to the output post.finally the large white and red wire goes to the output post. black goes to ground.again hope this helps Quote Link to comment Share on other sites More sharing options...
fastzcars Posted September 27, 2001 Share Posted September 27, 2001 hi guys, hope this helps. on the 240z the black and white wire comes from the ignition switch to the terminal 1 on the alt, there has to be a diode in that line if you are NOT conecting a 12v lamp.if you are using a lamp, an indacter bulb like a 194 can be used. as long as its NOT a light emitting diode. terminal 2 is a constant 12v,that one you can be connected to the large output post of the alt.terminal 1 is closest to the output post.finally the large white and red wire goes to the output post. black goes to ground.again hope this helps Quote Link to comment Share on other sites More sharing options...
fastzcars Posted September 27, 2001 Share Posted September 27, 2001 I forgot to add you SHOULD add a 14 gauge fusable link to the large white-red wire to protect the car should a short the alt. develops a short. Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted September 27, 2001 Share Posted September 27, 2001 Have you got the JTR book? I ran into this exact same problem when my one wire got fragged. The $40 replacement was 3 wire and I've wired it up with one wire going to the Z harness and a second wire jumpering to excite the doohicky (field?) inside The third wire, which I think would normally be used for a light, isn't hooked up as I recall. I pretty much just did it exactly the way JTR said it should be done.... Quote Link to comment Share on other sites More sharing options...
blueovalz Posted September 27, 2001 Share Posted September 27, 2001 Blake, I don't have that book, and yes, I did run a jumper from the field excitation lug to the charge lug, but this idiot light wire has me wigged out. Every manufacturer uses a different type of blub depending too, on the year is was made (led vs filament). So unless I get any more input, I'll go for the "194" bulb, or its equivalent resistance and watch the alternator real close. I'll get some pics of this thing out in a couple of weeks. You guys will enjoy (wonder about my state of mind) the set-up (what with my hood fitting up against the front of the motor). Quote Link to comment Share on other sites More sharing options...
John Scott Posted September 28, 2001 Share Posted September 28, 2001 I wired mine to my choke indicator bulb. Works fine. If the bulb were to fail the engine won't turn off. The diode might be a better solution, but I'm on my second conversion using the bulb method. JS [ September 27, 2001: Message edited by: John Scott ] Quote Link to comment Share on other sites More sharing options...
pparaska Posted September 28, 2001 Share Posted September 28, 2001 Terry, I don't know if the bulb really matters. It needs to have a few ohms of resistance is all, I believe. Also, if you've hooked the field wire to +12V, I am confused. Usually the field source wire IS the idiot light wire! You sure you don't mean the voltage sensing wire? That's the other small wire of the two small ones (the large wire being the alt output). If the battery is relocated, it's a good idea to run the voltage sensing wire all the way back to at least where the pos battery cable ends at the solenoid. If the charge wire has enough voltage drop (resistance), the battery will never get fully charged. Guys, I don't know what's been up with the site lately. Sometimes I can't open a post, etc. Maybe SuperDan knows? Quote Link to comment Share on other sites More sharing options...
blueovalz Posted September 28, 2001 Share Posted September 28, 2001 Something I should mention here is this is "new" wiring. The original wiring was gutting for the track, and I have only added an altenator just recently due to the conversion to street duty. So, with that said I have one 10 ga wire to charge the battery, and a 2nd smaller ga wire to excite the field from the battery also. This 3rd wire is the topic of my question. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted September 28, 2001 Share Posted September 28, 2001 Pete, I'm having the same problem posting new topics. Anyway, You may be correct about the voltage sensing wire. I may be wrong on my terminalogy. If indeed the field is excited by the bulb wire, then a low resistance sounds good. I've measured three different idiot light resistances. they ranged from 13 ohms to over 70 ohms. I will start with the highest and work down. Thanks for all the replies, guys. Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted September 28, 2001 Share Posted September 28, 2001 Heh, now I'm confused. I'm pretty darned sure that the wire that JTR says is for the bulb is simply NOT hooked up in my car. I can doublecheck if it would help but after searching here, finding this thread (early on), still being stumped, I simply followed the JTR advice and it's seemed fine so far. Need to go get my one wire alternator though - it was rebuilt. I'm told it didn't look too great inside too BTW - it was a ProForm unit. As for running a sensing wire to the back well... When I was troubleshooting my charging issue (bad alternator) I took some measurements between the alternator and the battery and saw NO voltage drop! Yup, I couldn't find but maybe a tenth of a volt difference. I can doublecheck if that sounds really whacky but it's what I recall. I ran stereo cable to the positive side and used a batteyr relocate kit for the ground. Ground comes right to the starter motor as well as the bodyframe in about 4 places I really figured I'd lose at least a half volt but so far it looks kosher, what a relief! Especially after the first starter seemd to labor so much on hot starts - I swore it was probably battery but nope! Quote Link to comment Share on other sites More sharing options...
pparaska Posted September 28, 2001 Share Posted September 28, 2001 Jim, if you use a big enough wire from the alternator output and run it to the pos battery cable at the starter solenoid, the sensing wire probably doesn't need to go to the battery, but just the alt output. I'd use at least 10 gage wire, but I used some 8 gage wire. I also ran 8 gage wire from the bottom pivot bolt (put a ring lug between the alt case and the bottom alt mount) back to the negative battery cable end that connects to the engine block near the starter. There can be voltage drops on both sides of the circuit, and my POR-15'd alternator mount didn't seem to have good continuity between the alt and the block where it's mounted. Details, details... Quote Link to comment Share on other sites More sharing options...
blueovalz Posted September 28, 2001 Share Posted September 28, 2001 Well then, based on what I've read here, I will use a short jumper off the charge wire to go to the sensing spade. The charging wire (8 awg) will still go to the battery via the emergency C/O switch (dead side), and the idiot light wire will come off a swithched 12v source, through a 1.5W bulb and then on to the idiot light spade. This now seems to make perfect sense, and Pete, you were correct, the field is excited through the idiot light circuit- No light, No charge. Thanks again, Terry Quote Link to comment Share on other sites More sharing options...
blueovalz Posted September 28, 2001 Share Posted September 28, 2001 That's the way I see it now. I just got off the phone with the rebuilder. He verified that the 12+ goes through the light and then to excite the field winding. According to him, with this wire left off, there will be no charge (no field excitation, no generator output). I asked "what if the bulb burns out" and he confirmed that no charge would exist. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted September 28, 2001 Share Posted September 28, 2001 I think the reason your car has no light Jim (nor does mine) is perhaps they're talking different alternators? He did call it a three wire, which is confusing, I have what they call the 'one wire' alternator, but it has the big output lug, and then the two wires, one voltage sensing and another for the bulb (optional according to JTR as you said), I've used no bulb and it charges. I can only assume they're talking a different alternator than I'm using. I'd have no problem adding a light if its of benefit though. Regards, Lone Quote Link to comment Share on other sites More sharing options...
pparaska Posted September 28, 2001 Share Posted September 28, 2001 Jim, you may have an alternator that's has some sort of bypass in it to turn on the field as soon as it hits a certain (low) rpm. The idiot light is a very old idea, and yes, if the bulb burns out, it won't charge. Maybe a relay instead of the bulb, and then run a bulb or LED off the relay. I'd think an automotive relay would have comparable coil resistance to a bulb, and would last longer. Of course, you might want to fuse this with a small fuse also. BTW, I like idiot lights. Maybe that says something about me. [ September 28, 2001: Message edited by: pparaska ] Quote Link to comment Share on other sites More sharing options...
blueovalz Posted September 28, 2001 Share Posted September 28, 2001 Lone, I was going to use a 1 wire, but the charatoristic "turn on" rpm was higher than I wanted (because of the particular way my alternator is mounted). So instead, I chose the more conventional 3 wire that would charge at any speed (abeit a very small charge at lower rpms). Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted September 28, 2001 Share Posted September 28, 2001 Lone, my setup is just like yours. I agree too, a light would be fine by me so long as burnout doesn't kill things. My previous alternator was a "one wire" that had the two additional outputs if I so desired to use them - it had a "turn on" RPM. Heh, yeah this is all somewhat confusing and I'm just happy my silly $40 alternator works now. Want my nice chrome 100amp one wire back though, need to see about that And Pete - NOTHING wrong with idiot lights. I'm pretty close to installing one for my coolant temp. I've had the thermostat stick ONCE for a short period of time, thankfully it was fine after it hit 210. However an idiot light in addition to the gauge to warn me of such an event would be a VERY good idea methinks! Maybe wire up the alternator to the same light? Quote Link to comment Share on other sites More sharing options...
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