burberry Posted February 8, 2015 Share Posted February 8, 2015 A couple of weeks ago, I had an RV repair shop replace my battery isolator, because the current isolator wasn't separating the batteries, and I was told I needed a new one. They replaced it with a Sure Power 70amp isolator. They also installed a battery switch to turn the house battery off as an added measure. However, when they called to tell me the job was done, they told me that my alternator was also bad. They asked if I wanted a mechanic down the road (who they'd called to determine this) to replace it. I told them I would have my mechanic do so. My mechanic put in a new alternator. When I picked the RV up, he told me that the RV place had hooked up the isolator incorrectly and it might be the reason the alternator blew. From what I could determine of what he'd done, he had wires running from the alternator to both the isolator and the starting battery, with the only used posts on the isolator being the alternator running in and the house battery wire running out. I was pretty sure this wasn't correct, but not confident enough to argue with him. Once I got home and tested things out with the system my mechanic rigged, everything that runs off 12v power still operates when the house battery is switched off, so the current setup isn't separating the batteries. That can't be right! (I know the battery switch on the house battery works, because when I disconnect the wire from the alternator to the isolator, the 12v lights/etc. operate when the house switch is on and do not operate when the house switch is off.) I have a general idea of how things should go - from the alternator to the A post on the isolator, and then from posts 1 and 2 to the starting and house batteries, respectively. But once you start following the wire toward the starting battery, I get lost and just don't think I can do this myself. I need help, and I just don't know who to trust. Any recommendations for solid RV repair folk, or even a local Toyhome owner, who can re-run the wires in the chassis area and then test to make sure everything both charges and is still separate? I'm really at my wits end. Quote Link to comment Share on other sites More sharing options...
Maineah Posted February 9, 2015 Share Posted February 9, 2015 It sounds like they installed a solid state isolator. Do you know if that what was on it to begin with? The alternator wiring has to be redone for a solid state isolator to work. You are on the right track the "A" terminal goes to the alt. B+ the 1 and 2 go to the batteries it makes no difference what battery is on one or two it will work either way. I'll assume your MH is reasonably late module so it will also require a 4th terminal on the isolator usually marked "E" that needs to have power to it with the key on. Now with the engine off you will have power on both terminals 1 and 2 that is normal but internally they are not joined to the "A" terminal they are blocked by internal diodes inside for the isolator. The diodes are like a one way valve they only allow current to flow from the "A" terminal not to it. So with the engine off you should have no voltage at the "A" terminal. That's how the isolator works if that all ok then you need to fine some one that can figure out what they did with the switch setup and it sounds like some thing you don't need I kind of wonder if there is an original isolator relay still in place. Quote Link to comment Share on other sites More sharing options...
burberry Posted February 9, 2015 Author Share Posted February 9, 2015 i have this pic of the old one (you actually gave me some good information before, when I was thinking of doing the job myself): I have a 1987 Toyota Sunrader, but there wasn't an ignition wire there before. Quote Link to comment Share on other sites More sharing options...
zero Posted February 9, 2015 Share Posted February 9, 2015 Here are the wiring diagrams assuming you have the Sure Power 70 amp non-relay type isolator. If you have something different, like a "Smart" relay, then it does make a difference on which charge wire goes to which battery. Quote Link to comment Share on other sites More sharing options...
Maineah Posted February 9, 2015 Share Posted February 9, 2015 i have this pic of the old one (you actually gave me some good information before, when I was thinking of doing the job myself): I have a 1987 Toyota Sunrader, but there wasn't an ignition wire there before. There should be. The external regulated alternator did not require one. Quote Link to comment Share on other sites More sharing options...
Maineah Posted February 9, 2015 Share Posted February 9, 2015 The connections should be direct to both batteries with nothing in between except for maybe a circuit breaker no relays switches etc.With the engine off there should be no voltage at the "A" terminal ( digital multimeters can be deceptive they may show some voltage but not much) Check the voltage at both batteries then check the voltage at terminals 1 and 2 to ground they should be close to the the battery reading. Next start the engine check the voltage at the "A" terminal it should be some thing around 13+ volts do the same at terminals 1 and 2 it will be lower by about .7 volts that is normal bump up the engine speed and all the voltages should climb. Next go to the batteries and recheck their voltages it should be some thing close to terminals 1 and 2. If the voltages are not close to the terminal voltages there is some thing up with the wiring in between. Quote Link to comment Share on other sites More sharing options...
Derek up North Posted February 9, 2015 Share Posted February 9, 2015 And always remember to check the (often forgotten) ground for each battery. Quote Link to comment Share on other sites More sharing options...
dolcecanto Posted April 30, 2016 Share Posted April 30, 2016 New member. We’ve been having battery problems for several years. Replaced the starter, then the inverter(?) board in the cabin of the RV, then the alternator. Recently the ’87 sunrader would not start. An RV mechanic came to our house and said the cables were not connected correctly. He changed them, got the vehicle to start. But the next day the RV would not start again. Can you tell from these photos anything more? Is the item bordered in red my isolator? We see the solenoid is rusty, so we are replacing that. Help. My husband has a broken leg and can’t get out to the vehicle to assist the mechanic who will be arriving on Tuesday. I’d like to make sure he knows which is the isolator. IIRC, he didn’t seem to recognize the fixture bordered in red here. (I am a literature major, no knowledge of vehicles, but trying to learn.) Thank you in advance. Quote Link to comment Share on other sites More sharing options...
linda s Posted May 1, 2016 Share Posted May 1, 2016 The isolater is the rusty round thing attached to your washer bin. Sunrader use 4 pole isolaters so they have a separate ground. Don't really think it's the cause of your not starting. Linda S Quote Link to comment Share on other sites More sharing options...
dolcecanto Posted May 1, 2016 Share Posted May 1, 2016 Thank you! Quote Link to comment Share on other sites More sharing options...
zero Posted May 1, 2016 Share Posted May 1, 2016 18 hours ago, dolcecanto said: New member. Recently the ’87 sunrader would not start. An RV mechanic came to our house and said the cables were not connected correctly. He changed them, got the vehicle to start. But the next day the RV would not start again. When you say "would not start" do you mean it would not crank over, or it DOES crank over but won't start? If it was not cranking over - from what you have said, the cause-and-effect sounds like this. Cranking battery was dead or had a bad connection but the "house" battery was okay. "Mechanic" undid the proper connections on the isolator-relay and joined both batteries together on one post. Then the added power from the house battery let it start, until it TOO got drained down. Just a guess going by what you have told us. Rust on the OD of the relay means nothing. Quote Link to comment Share on other sites More sharing options...
fred heath Posted May 1, 2016 Share Posted May 1, 2016 On 2/7/2015 at 6:32 PM, burberry said: A couple of weeks ago, I had an RV repair shop replace my battery isolator, because the current isolator wasn't separating the batteries, and I was told I needed a new one. They replaced it with a Sure Power 70amp isolator. They also installed a battery switch to turn the house battery off as an added measure. However, when they called to tell me the job was done, they told me that my alternator was also bad. They asked if I wanted a mechanic down the road (who they'd called to determine this) to replace it. I told them I would have my mechanic do so. My mechanic put in a new alternator. When I picked the RV up, he told me that the RV place had hooked up the isolator incorrectly and it might be the reason the alternator blew. From what I could determine of what he'd done, he had wires running from the alternator to both the isolator and the starting battery, with the only used posts on the isolator being the alternator running in and the house battery wire running out. I was pretty sure this wasn't correct, but not confident enough to argue with him. Once I got home and tested things out with the system my mechanic rigged, everything that runs off 12v power still operates when the house battery is switched off, so the current setup isn't separating the batteries. That can't be right! (I know the battery switch on the house battery works, because when I disconnect the wire from the alternator to the isolator, the 12v lights/etc. operate when the house switch is on and do not operate when the house switch is off.) I have a general idea of how things should go - from the alternator to the A post on the isolator, and then from posts 1 and 2 to the starting and house batteries, respectively. But once you start following the wire toward the starting battery, I get lost and just don't think I can do this myself. I need help, and I just don't know who to trust. Any recommendations for solid RV repair folk, or even a local Toyhome owner, who can re-run the wires in the chassis area and then test to make sure everything both charges and is still separate? I'm really at my wits end. I sent you a pm. I live in Raleigh. Quote Link to comment Share on other sites More sharing options...
dolcecanto Posted May 1, 2016 Share Posted May 1, 2016 2 hours ago, jdemaris said: When you say "would not start" do you mean it would not crank over, or it DOES crank over but won't start? If it was not cranking over - from what you have said, the cause-and-effect sounds like this. Cranking battery was dead or had a bad connection but the "house" battery was okay. "Mechanic" undid the proper connections on the isolator-relay and joined both batteries together on one post. Then the added power from the house battery let it start, until it TOO got drained down. Just a guess going by what you have told us. Rust on the OD of the relay means nothing. The lights on the dash and the radio worked, It would not crank. So as one mechanic at the RV place told me that I could charge the camper battery by plugging it in, and even though the camper battery had shown power by the home visiting mechanic, I thought what the heck. I turned on shore power, plugged in the RV shore power to my home electricity for 7 hours, returned, and the RV started. Does this mean someone incorrectly wired my camper battery to the starter? Thank you for your help. Quote Link to comment Share on other sites More sharing options...
zero Posted May 1, 2016 Share Posted May 1, 2016 48 minutes ago, dolcecanto said: The lights on the dash and the radio worked, It would not crank. So as one mechanic at the RV place told me that I could charge the camper battery by plugging it in, and even though the camper battery had shown power by the home visiting mechanic, I thought what the heck. I turned on shore power, plugged in the RV shore power to my home electricity for 7 hours, returned, and the RV started. Does this mean someone incorrectly wired my camper battery to the starter? Thank you for your help. If the lights in the dash worked and did not go dim when you turned the key to "crank" - then battery power (from the main battery) is not the problem. If battery power is low, and starter in good shape. the lights should go dim when it fails to turn over. The way your isolator is bypassed right now - plugging in your converter/charger to shore-power would charge both batteries. Now - if are are saying that charging the batteries makes it start okay, but when sitting for awhile and NOT on a charger it does NOT start - then I'm a little stumped. Need to take some simple voltage readings. Battery (cranking) should be near 13 volts when not being used and should drop to 9-10 volts when the starter is cranking properly. Quote Link to comment Share on other sites More sharing options...
dolcecanto Posted May 1, 2016 Share Posted May 1, 2016 1 hour ago, jdemaris said: If the lights in the dash worked and did not go dim when you turned the key to "crank" - then battery power (from the main battery) is not the problem. If battery power is low, and starter in good shape. the lights should go dim when it fails to turn over. The way your isolator is bypassed right now - plugging in your converter/charger to shore-power would charge both batteries. Now - if are are saying that charging the batteries makes it start okay, but when sitting for awhile and NOT on a charger it does NOT start - then I'm a little stumped. Need to take some simple voltage readings. Battery (cranking) should be near 13 volts when not being used and should drop to 9-10 volts when the starter is cranking properly. Thank you again. I'll try to get some voltage readings. Also, I just went out this morning to start it and it started ok. However, after 5 -10 minutes, the battery light and the brake light came on in the dash. Stumped why that would happen. Quote Link to comment Share on other sites More sharing options...
linda s Posted May 1, 2016 Share Posted May 1, 2016 Battery light and brake light on at the same time in a Toyota means your alternator is bad. Doesn't matter if it's been replaced or not. Lots of replacement alternators aren't good. Linda S Quote Link to comment Share on other sites More sharing options...
zero Posted May 1, 2016 Share Posted May 1, 2016 As I recall, when the the charge and brake light comes on - a bad alternator is a common cause but NOT the only possible cause. I think with an 87, a bad fuse, bad fusible link, bad connection, or bad charge relay can also cause the problem. Not fresh on my mind though and I'm not in the mood to study a 1987 schematic. Best thing is to check the alternator first and if it checks OK - obviously there are more things to check. Quote Link to comment Share on other sites More sharing options...
dolcecanto Posted May 1, 2016 Share Posted May 1, 2016 1 hour ago, jdemaris said: As I recall, when the the charge and brake light comes on - a bad alternator is a common cause but NOT the only possible cause. I think with an 87, a bad fuse, bad fusible link, bad connection, or bad charge relay can also cause the problem. Not fresh on my mind though and I'm not in the mood to study a 1987 schematic. Best thing is to check the alternator first and if it checks OK - obviously there are more things to check. Thank you to both Linda and you. Very helpful. The mechanic who put on the alternator has a shop only 4 blocks away. I will call him tomorrow. Quote Link to comment Share on other sites More sharing options...
Maineah Posted May 2, 2016 Share Posted May 2, 2016 The light is tied into the break warning system also if the fluid is low it will come on but in your case you seem to have a charging issue it kind of sound to me like it maybe a good ideal to go to a shop that deals with automotive electrical systems connecting both cables to the starting battery kind of defeats the isolators purpose. Quote Link to comment Share on other sites More sharing options...
dolcecanto Posted May 5, 2016 Share Posted May 5, 2016 On May 1, 2016 at 9:20 AM, jdemaris said: If the lights in the dash worked and did not go dim when you turned the key to "crank" - then battery power (from the main battery) is not the problem. If battery power is low, and starter in good shape. the lights should go dim when it fails to turn over. The way your isolator is bypassed right now - plugging in your converter/charger to shore-power would charge both batteries. Now - if are are saying that charging the batteries makes it start okay, but when sitting for awhile and NOT on a charger it does NOT start - then I'm a little stumped. Need to take some simple voltage readings. Battery (cranking) should be near 13 volts when not being used and should drop to 9-10 volts when the starter is cranking properly. On the sun reader wiring diagram published it shows the isolator/solenoid connected to the alternator. The shop had wired the alternator directly to the starting battery. Is this incorrect? Apologies for electrical wiring ignorance. Quote Link to comment Share on other sites More sharing options...
Maineah Posted May 5, 2016 Share Posted May 5, 2016 1 hour ago, dolcecanto said: On the sun reader wiring diagram published it shows the isolator/solenoid connected to the alternator. The shop had wired the alternator directly to the starting battery. Is this incorrect? Apologies for electrical wiring ignorance. If it is a relay type (like your picture) yes the alternator is wired directly to the starting battery. There seems to be an issue with your picture though it appears to have two battery cables connected to the same terminal that is not correct that defeats the purpose of the isolator. Quote Link to comment Share on other sites More sharing options...
zero Posted May 6, 2016 Share Posted May 6, 2016 2 hours ago, dolcecanto said: On the sun reader wiring diagram published it shows the isolator/solenoid connected to the alternator. The shop had wired the alternator directly to the starting battery. Is this incorrect? Apologies for electrical wiring ignorance. It looks to me like the cranking battery and "house" battery are both joined on one post, while the white 10 gauge wire (approx) that comes from the alternator is on the other post. That is absolutely wrong. Wired that way, neither battery gets any charge unless the isolator-relay is energized and when not- alternator charge current has nowhere to go and might fry the alternator. Just a guess since I cannot see much with the photos. Quote Link to comment Share on other sites More sharing options...
dolcecanto Posted May 6, 2016 Share Posted May 6, 2016 1 hour ago, Maineah said: If it is a relay type (like your picture) yes the alternator is wired directly to the starting battery. There seems to be an issue with your picture though it appears to have two battery cables connected to the same terminal that is not correct that defeats the purpose of the isolator. Thank you. I will copy your posts for the mechanic tomorrow. Quote Link to comment Share on other sites More sharing options...
dolcecanto Posted May 6, 2016 Share Posted May 6, 2016 3 minutes ago, jdemaris said: It looks to me like the cranking battery and "house" battery are both joined on one post, while the white 10 gauge wire (approx) that comes from the alternator is on the other post. That is absolutely wrong. Wired that way, neither battery gets any charge unless the isolator-relay is energized and when not- alternator charge current has nowhere to go and might fry the alternator. Just a guess since I cannot see much with the photos. Thank you, this is information I will give mechanic tomorrow. Quote Link to comment Share on other sites More sharing options...
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