dolphinguy Posted February 4, 2012 Share Posted February 4, 2012 1979 toy dolphin battery not charging took alt. to auto parts and tested it twice and its good. both batteries are about brand new.any advice where i look next.someone suggested the regulator but from what ive read so far the isolator has been mentioned.need help on this one thanks larry Quote Link to comment Share on other sites More sharing options...
Vanman Posted February 4, 2012 Share Posted February 4, 2012 dolphinguy 1979 toy dolphin battery not charging took alt. to auto parts and tested it twice and its good. both batteries are about brand new.any advice where i look next.someone suggested the regulator but from what ive read so far the isolator has been mentioned.need help on this one thanks larry The OEM battery isolator will be a silver can half the size of a soup can mounted vertically on the drivers side firewall. One big wire to the Toyota battery, another big wire to the house battery, small wire to the alternator. Return side wiring is the grounded case bolted to the the firewall. It's just a relay, after the engine is running the alternator sense wire puts out enough power to energise the relay coil which will magnetically attract the relay armature connecting the contacts inside the can, which electrically connects the battery wire to the wire going to the house battery. There is also usually a fuse that looks like a small terminal block bolted to the inside of the engine compartment close to and wired to one of the big wires. A bad connection, broken wire/connector or failure of either component will prevent the alternator from charging the house battery. If a visual look and gentle tugging on the various connections don't show the problem you should get a Volt Meter and put one lead on a good ground and check for voltage, Toyota batt red terminal, fuse terminal to Toyota batt, fuse terminal that connects to the isolator, Toyota battery side of isolator, output terminal of isolator to house battery. If all this checks good possable open wiring between house terminal of isolator to house battery. Remember these are low voltage high current connections so loose corroded bad connections will not work well, if at all. Good luck OH OH I forgot to mention when the engine is running you should have 12 volts to ground on the alternator sense wire (the small one) to the isolator coil to activate it. vanman Quote Link to comment Share on other sites More sharing options...
Totem Posted February 4, 2012 Share Posted February 4, 2012 1979 toy dolphin battery not charging took alt. to auto parts and tested it twice and its good. both batteries are about brand new.any advice where i look next.someone suggested the regulator but from what ive read so far the isolator has been mentioned.need help on this one thanks larry Bad alternators can test good on bad testers: I had a bad autozone alternator test good at autozone but bad at Nappa...It was charging right at the threshold that trigger check engine light to flicker! have it tested at two independent shops A bad fusible link will cause this behavior you have described if alternator is good. Check the links for burns pull your battery ground if it is rusty, clean it till metal, grease it with bulb grease then bolt back tight if no lights in cab, check the fuse under the dash and the fuses under the hood if it is the alternator; get a nice powermaster; well worth the cost and can run fridge while driving. Quote Link to comment Share on other sites More sharing options...
Maineah Posted February 4, 2012 Share Posted February 4, 2012 If the isolator is a rely type the truck battery will charge even if it's bad the coach battery may not. The solid state type can give you a no charge issue if it's bad for both or either battery. Being as old as it is there are many things that can give you problems yours has an external regulator the alternator may be fine when tested but if the regulator is bad it won't charge once it's back on the truck. The wiring is a bit complex with the external regulator so a good diagram and volt meter is going to be your next step. Quote Link to comment Share on other sites More sharing options...
Totem Posted February 4, 2012 Share Posted February 4, 2012 If the isolator is a rely type the truck battery will charge even if it's bad the coach battery may not. The solid state type can give you a no charge issue if it's bad for both or either battery. Being as old as it is there are many things that can give you problems yours has an external regulator the alternator may be fine when tested but if the regulator is bad it won't charge once it's back on the truck. The wiring is a bit complex with the external regulator so a good diagram and volt meter is going to be your next step. I agree with this though my own truck has the regulator bolted on the alternator; if its bad it tests bad. pre 1985 models may have a separate regulator. As for the isolator, its easy enough to rule out as Maineh states; simply disconnect it and connect direct to alternator and test via voltimeter. this will do two things; you can drive but your cab battery no longer charges off of the alternator. Good Luck! Quote Link to comment Share on other sites More sharing options...
Derek up North Posted February 4, 2012 Share Posted February 4, 2012 1979 toy dolphin battery not charging took alt. to auto parts and tested it twice and its good. both batteries are about brand new.any advice where i look next.someone suggested the regulator but from what ive read so far the isolator has been mentioned.need help on this one thanks larry Check this Thread for info and a picture of the separate voltage regulator fitted to pre-'83 Toyotas. I assume it's at least similar to your '79. http://toyotamotorhome.org/forums/index.php?showtopic=4400 Best to get your hands on a Factory Service Manual and a multimeter if you hope to try and solve this problem yourself. Quote Link to comment Share on other sites More sharing options...
waiter Posted February 4, 2012 Share Posted February 4, 2012 I assume your truck battery is charging OK and your coach battery is not. Is this correct? Is this a new problem, i.e. it was working, but now its not. JOhn Mc 88 Dolphin 4 Auto Quote Link to comment Share on other sites More sharing options...
Maineah Posted February 5, 2012 Share Posted February 5, 2012 If your isolator is a relay type there are no wiring changes as far as the alternator is concerned it's output wire goes to the truck battery through the stock Toyota wiring you could remove the entire set up and the truck battery will still charge. There is a wire that goes to the relay from the truck battery, once energized by the key switch the relay closes and joins both batteries together. If you are indeed having truck battery issues you need to correct that first then move on to the coach battery system. Now that being said if the isolator is solid state it will be a box maybe 3X6" with cooling fins there are 3 or 4 terminals (forget the small one) one will be marked "A " that is the output lead from the alt. one is marked 1 the other 2 they are the battery leads. Usually the #1 terminal is the truck battery but it could be #2 it does not matter they will work fine reversed the other lead is the one for the coach. If you join 1and 2 to the "A" terminal that will bypass the isolator if it has 4 terminals (I do not think the external regulator system needs the 4th wire) the small wire is need to make the isolator work with the alt. but it is not need if you bypass the isolator if it charges then the isolator is suspect. I'm guessing that you have the relay type it's pretty much what they put on most from the factory it's a lot simpler and cheaper set up. Quote Link to comment Share on other sites More sharing options...
dolphinguy Posted February 12, 2012 Author Share Posted February 12, 2012 If your isolator is a relay type there are no wiring changes as far as the alternator is concerned it's output wire goes to the truck battery through the stock Toyota wiring you could remove the entire set up and the truck battery will still charge. There is a wire that goes to the relay from the truck battery, once energized by the key switch the relay closes and joins both batteries together. If you are indeed having truck battery issues you need to correct that first then move on to the coach battery system. Now that being said if the isolator is solid state it will be a box maybe 3X6" with cooling fins there are 3 or 4 terminals (forget the small one) one will be marked "A " that is the output lead from the alt. one is marked 1 the other 2 they are the battery leads. Usually the #1 terminal is the truck battery but it could be #2 it does not matter they will work fine reversed the other lead is the one for the coach. If you join 1and 2 to the "A" terminal that will bypass the isolator if it has 4 terminals (I do not think the external regulator system needs the 4th wire) the small wire is need to make the isolator work with the alt. but it is not need if you bypass the isolator if it charges then the isolator is suspect. I'm guessing that you have the relay type it's pretty much what they put on most from the factory it's a lot simpler and cheaper set up. thank you got side tracked for a few days but went out to the toy and bypassed the isolator. it was the one with the fins you mentioned. it now charges the truck battery just fine.will get isolator and be great. again thanks to all that posted. i love this forum larry Quote Link to comment Share on other sites More sharing options...
waiter Posted February 13, 2012 Share Posted February 13, 2012 This is good news. In order to keep it simple, you may consider the mechanical type (looks like an old Ford Starter relay) These are easy to wire up and are pretty much fool proof. John Mc 88 Dolphin 4 Auto Quote Link to comment Share on other sites More sharing options...
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