dirtbox Posted July 23, 2009 Share Posted July 23, 2009 Hi all. Searched till exhausted list and I couldn't find anything so here goes. Since my 12 to 24V swap I have had a problem with my charge warning light. I'm thinking I have blown the resistor that works along side the warning light as my light only dims with higher revs. The alternator will self excite and it does until I put lights on- well, the light comes back on as soon as there is any drain on the electrics. Can I replace with a 24V resistor and if so where would I get one from? I have heard that some just bypass with some wire bared at each end but why is the resistor there if you can just bypass it? Anyway, thanks in advance for any advice! Cheers, Paul. Quote Link to comment Share on other sites More sharing options...
Ex Member Posted July 23, 2009 Share Posted July 23, 2009 There should be no resistor in the circuit. The light showing means you have a bad rectifier. Get it fixed as the AC voltage destroys everything else really quick..... Quote Link to comment Share on other sites More sharing options...
dirtbox Posted July 23, 2009 Author Share Posted July 23, 2009 The light showing means you have a bad rectifier. Is that inside the alternator itself? I have tried a direct current to the alt and it seemed to charge Ok? I have looked at the workshop manual and there looks like a circuit that runs with the light, and I just guessed that if it failed it took the route via the light switching it on. If its inside the alternator I'l have to get my mate to look as Its a hitachi and I don't have any manual for it so not sure what I'm looking for. Thanks again! Quote Link to comment Share on other sites More sharing options...
dirtbox Posted July 24, 2009 Author Share Posted July 24, 2009 The light showing means you have a bad rectifier. Is that inside the alternator itself? Probably not made any sense as usual with the question! Any ideas? Quote Link to comment Share on other sites More sharing options...
western Posted July 25, 2009 Share Posted July 25, 2009 worth having the alternator bench tested at your nearest good auto eletrics place, they can tell if it's misbehaving & advise/repair it. which engine are we talking about as the wiring diagram can appear here Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted July 25, 2009 Share Posted July 25, 2009 How has the 12 - 24 voltage change been made? Are you feeding the new 24v alternator with 24v through a 24v charge warning lamp? Quote Link to comment Share on other sites More sharing options...
dirtbox Posted July 26, 2009 Author Share Posted July 26, 2009 which engine are we talking about as the wiring diagram can appear here Its a Nissan FD35t. You probably won't find much info on it though! I wired it in using my existing 2.5 petrol loom and just connected everything to its equivalent on the engine. How has the 12 - 24 voltage change been made? By just changing everything on the vehicle to a 24V version, i.e. bulbs, relays, motors etc. Are you feeding the new 24v alternator with 24v through a 24v charge warning lamp? Yes, 24V alternator fed with a 24V supply through the existing charge warning light circuit that has a 24v/1.2W bulb in place. Could the bulb wattage make any difference? Thanks for the replies so far! Quote Link to comment Share on other sites More sharing options...
western Posted July 26, 2009 Share Posted July 26, 2009 I wired it in using my existing 2.5 petrol loom and just connected everything to its equivalent on the engine. within the loom is a resistor that connects each side of the charge warning light it connects they brown/yellow wire from the Alt WL terminal to the White wire that goes to the charge light, you can see it on this diagram for 4 cylinder petrol vehicles item 62 in the upper right of diagram. Quote Link to comment Share on other sites More sharing options...
dirtbox Posted July 26, 2009 Author Share Posted July 26, 2009 Thanks western. Yes that is the resistor I mentioned in the first post. So would that have possibly blown? Being from a 12V system and having 24V put through it? I don't know if I need to get a 24V one or not. Thanks again. Paul Quote Link to comment Share on other sites More sharing options...
western Posted July 27, 2009 Share Posted July 27, 2009 without removing it from the loom I can't say what amps/ohms it is rated at. possibly you've poopped the 12v one by feeding 24v through it. I don't know if the 24v loom has one fitted, only because I've never stripped a 24v vehicle to find out. Quote Link to comment Share on other sites More sharing options...
errol209 Posted July 27, 2009 Share Posted July 27, 2009 without removing it from the loom I can't say what amps/ohms it is rated at. possibly you've poopped the 12v one by feeding 24v through it. I don't know if the 24v loom has one fitted, only because I've never stripped a 24v vehicle to find out. I'd go with that (if its fitted) 'cos power is volts squared / resistance - you've probably fried it (by getting it to dissipate four times the power). To get the same current drop you need a resistor double the normal value (since amps = volts / resistance) and twice the power rating. Anyone know the right value for a 12V system? There could be a toasty bit of loom somewhere ... Quote Link to comment Share on other sites More sharing options...
dirtbox Posted July 27, 2009 Author Share Posted July 27, 2009 Thanks for the replies. Could I potentially be causing a problem by skipping the resistor with a piece of cable? Keep wanting to try it but my fear of electrics is stopping me! Quote Link to comment Share on other sites More sharing options...
western Posted July 27, 2009 Share Posted July 27, 2009 you need to know the resistance rating of the subject resistor before going any further & if not sure of elects get a auto electrician to help Quote Link to comment Share on other sites More sharing options...
dirtbox Posted July 27, 2009 Author Share Posted July 27, 2009 Well I'm thinking the best thing to do is try and remove the suspect resistor and as advised get my mate at work to point me in the right direction. Thanks all for the help anyways! Cheers, Paul Quote Link to comment Share on other sites More sharing options...
errol209 Posted July 28, 2009 Share Posted July 28, 2009 Well I'm thinking the best thing to do is try and remove the suspect resistor and as advised get my mate at work to point me in the right direction.Thanks all for the help anyways! Cheers, Paul Paul, If you do find a resistor and work out any details for it (resistance value in particular, location, etc.) please post the info., as this question crops up now and again Quote Link to comment Share on other sites More sharing options...
dirtbox Posted July 29, 2009 Author Share Posted July 29, 2009 If you do find a resistor and work out any details for it (resistance value in particular, location, etc.) please post the info., as this question crops up now and again Will do asap! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.