Esky_addict Posted October 13, 2013 Share Posted October 13, 2013 Hi all ill just aqcuired a surf with a 3.8 in it and it starts and idles fine but sputters and farts around when taking off. I think that the alternators poked but dont have a multimeter only a test light and when i put it on the "S" terminal of the alternator there is no life. Should that be live? Quote Link to comment Share on other sites More sharing options...
Yowzer Posted October 13, 2013 Share Posted October 13, 2013 The S is the voltage sense, it should be connected to the battery via a separate cable from the main power cable. It's purpose is to monitor the battery voltage so the alternator can compensate for voltage drop across the power cable. So yeah it should be live, if it's not connected then the alternator may not put out as many volts as required. I've found they seem to still work sweet with it disconnected though, so slap a meter across the battery and give it a bit of rev and see what the voltage is. You should be seeing 14 odd V at the battery. Quote Link to comment Share on other sites More sharing options...
Esky_addict Posted October 13, 2013 Author Share Posted October 13, 2013 ok. i have nothing on the sense wire and no mutimeter to check it with. It starts and idles then when i turn the electric fans and the lights on it idles rough. Quote Link to comment Share on other sites More sharing options...
CaMpylobacter Posted October 13, 2013 Share Posted October 13, 2013 sounds like you'll wanna hook it up. definitely check all your earths and shit, and get a multimeter to check with. Quote Link to comment Share on other sites More sharing options...
Yowzer Posted October 13, 2013 Share Posted October 13, 2013 Multi meters aren't pricey for a basic one. Go to Repco, Supercheap, Jaycar etc and buy a $20 unit. It'll do the job fine. Quote Link to comment Share on other sites More sharing options...
Esky_addict Posted October 13, 2013 Author Share Posted October 13, 2013 yeah had a quick squizz at the earths. Was supposed to say have no voltage on the s wire i had it plugged in. Will whip it off tomorrow and take it to get tested. The other kicker is that the factory volt meter reads around 14 volts and doesent drop away down when accessories are turned on. Quote Link to comment Share on other sites More sharing options...
vivaspeed Posted October 13, 2013 Share Posted October 13, 2013 S wire on Toyotas is Signal (or Sense). It needs to be connected from the Alternator to the Battery (should be switched, fused via the main relay). I have not so fond memories of trying to get an alternator on a 2TG trying to run with no S wire in place. Voltage will be present on the battery side of the wire. If you're measuring the voltage on S off the back of the Alt it will be zero volts from memory. Quote Link to comment Share on other sites More sharing options...
coldturkey Posted October 13, 2013 Share Posted October 13, 2013 Voltage will be present on the battery side of the wire. If you're measuring the voltage on S off the back of the Alt it will be zero volts from memory. Wat... That's not how electrickery works. Unless the wire has resistance in it and is grounded at the alternator lol 1 Quote Link to comment Share on other sites More sharing options...
vivaspeed Posted October 13, 2013 Share Posted October 13, 2013 Wat... That's not how electrickery works. Unless the wire has resistance in it and is grounded at the alternator lol Maybe I explained it poorly - I'm not trying to redefine how physics work. But what I meant was if you measured the voltage on the S wire ( wrt. negative/earth/chassis with the wire disconnected off the alternator) off the back of the alternator it will be 0, if you measure the wire from the battery it will be +12 - i.e. it takes the reference voltage from the battery rather than pokes power back to the battery along the S wire. (fucking two electrical engineers arguing over how electricity works, lol) Edit: I think you were making reference to the voltage drop along the wire, i.e. due to resistance in the wire and a complete circuit allowing current to flow. That's not at all what I meant. Quote Link to comment Share on other sites More sharing options...
Ned Posted October 13, 2013 Share Posted October 13, 2013 Let me join in too then? Apply power to sense wire and see if it works better. Off the top off my head (and I'll likely get it wrong) there is sense, lamp ignitiona nd battery. Battery goes through fuseable link to battery (via the giant terminal on the back of the alternator) Ignition goes via key switch to accessory so it's live when the car is running Lamp (in most cases) MUST go through the dash light (which must obviously not be blown) Sense goes to battery through another fuse or fusable link. Fuse or fusable link must be physically close to the battery and battery and sense need their own wire, you can't just connect sense to the battery terminal on the back of the alternator. Quote Link to comment Share on other sites More sharing options...
Yowzer Posted October 13, 2013 Share Posted October 13, 2013 Pretty sure your problem isn't relates to the alternator. You say it splutters when taking off. Does it hold a constant speed but stuffs around under acceleration? Or does it wanna do nothing except idle? Quote Link to comment Share on other sites More sharing options...
Esky_addict Posted October 13, 2013 Author Share Posted October 13, 2013 Let me join in too then? Apply power to sense wire and see if it works better. That was the first thing I tryed as a mate had a VN in our younger days and the "S" wire had failed/Blown fuse somewhere back the loom. Im thinking that there isn't enough power to keep the engine running which Is why im thinking alternator. Just chucked a multimeter on and battery volts are 11.5 so have removed alternator to get checked out. Quote Link to comment Share on other sites More sharing options...
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