Garthy Posted April 18, 2009 Share Posted April 18, 2009 Hi, My alternator went kaput so I bought an A127/65 (STC234G), however I'm having trouble geting it to work. The alternator I removed had a nice socket on the back which I plugged the three connections into, however this new on has three post connections. I've worked out which one is D+ (Warning light) as this is the smallest post so I've connected the smallest wire to it. This leaves two other posts B+ and D+. How do I know which wire goes where, when both my other wires are brown and the same thckness. I've connected them both way round to see what happens and I can only get 12.8V across the battery terminals (13.1V if I rev the enigine) no matter which way round the wires are. I've taken the volts off the back of both posts of the alternator and one reads 12V and the other 12.8V. Should I not be getting closer to 14V. Attached is a picture of my alternator with labels. What do the black boxes with wires do? Do they need to be there?? It's a 200tdi 90 (1992) Thanks. Quote Link to comment Share on other sites More sharing options...
markyboy Posted April 18, 2009 Share Posted April 18, 2009 Hi,My alternator went kaput so I bought an A127/65 (STC234G), however I'm having trouble geting it to work. The alternator I removed had a nice socket on the back which I plugged the three connections into, however this new on has three post connections. I've worked out which one is D+ (Warning light) as this is the smallest post so I've connected the smallest wire to it. This leaves two other posts B+ and D+. How do I know which wire goes where, when both my other wires are brown and the same thckness. I've connected them both way round to see what happens and I can only get 12.8V across the battery terminals (13.1V if I rev the enigine) no matter which way round the wires are. I've taken the volts off the back of both posts of the alternator and one reads 12V and the other 12.8V. Should I not be getting closer to 14V. Attached is a picture of my alternator with labels. What do the black boxes with wires do? Do they need to be there?? It's a 200tdi 90 (1992) Thanks. Hi, The 2 thick brown wires on your original plug went to the same connection in the alternator, these are the wires which charge the battery. Therefore, I think these 2 need to go to the same connector, which is the B+ if IIRC. The two black boxes are suppressors to prevent radio interference. I think the "spare" terminal you will then be left with is the feed for a tachometer. Have you tried doing a search on here for information. I'm sure there should be something useful on here to help you. Failing that, hopefully someone else with better "electrickery" knowledge will be along shortly to confirm/deny these suggestions. Mark. Quote Link to comment Share on other sites More sharing options...
Garthy Posted April 18, 2009 Author Share Posted April 18, 2009 You could be onto somethhing there! Right, back out I go and have a tweak. Thanks. Yes, I've done plenty of searching on here but it still doesn't make sense. Quote Link to comment Share on other sites More sharing options...
western Posted April 18, 2009 Share Posted April 18, 2009 put the 2 thick brown wires on B+ the W terminal is for a rev counter feed NOT the warning light D+ for warning light on dash panel Quote Link to comment Share on other sites More sharing options...
western Posted April 18, 2009 Share Posted April 18, 2009 found this in a vehicle electrical book I've got. Lucas ind = warning light + = main output to battery/starter S = battery sense [not on all alternators] Other alternators D+,61,L,lamp,N = warning light B,B+,Bat,30 = main output to battery/starter S = battery Quote Link to comment Share on other sites More sharing options...
Garthy Posted April 18, 2009 Author Share Posted April 18, 2009 Thanks. I've moved both wires onto B+ and I'm now getting 13.5V over the battery. Reading on the forum some people say this is okay and others say it's not so good. I know the other two vehicles (VW Polo & VW Passat) in the household have 14V going across the terminals. I now need to move the warning light from W to D+, however I don't think that will change the P.D. on the battery. Quote Link to comment Share on other sites More sharing options...
western Posted April 18, 2009 Share Posted April 18, 2009 up the revs to 2000 then check the alternator output at the battery Quote Link to comment Share on other sites More sharing options...
Garthy Posted April 18, 2009 Author Share Posted April 18, 2009 Still just the 13.5V. hmmm Quote Link to comment Share on other sites More sharing options...
Aragorn Posted April 18, 2009 Share Posted April 18, 2009 the optimal charging voltage is 14.1v so its fair to expect 14v on a healthy car, If you dont have the warning light connected to the d+ terminal, you may not get the proper charging voltage, as the warning light feed is used to excite the alternator to allow it to start generating power. The other issue might be a bad earth between the alternator and the block. Try clamping a jump lead between the alternator casing and the block/chassis. Quote Link to comment Share on other sites More sharing options...
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