84TOYRV Posted July 13, 2016 Share Posted July 13, 2016 We were wondering why the truck battery in my 84 Toy Dolphin was always running down. We disconnected the coach battery and turned on the coach lights. They worked, along with the water pump. We disconnected the truck battery and connected the coach battery. Turned on the coach lights. Nothing worked. How could this be? I have no idea what to look for. It's like they're not hooked up right. We've been having battery troubles lately, where we haven't a few years ago. I did get a tune up done about the same time that we started having battery problems, but I just don't know if it's relevant or not. I know that there is an isolation unit, but not sure where that is or if it's the problem. Thank you for any help, guys. Quote Link to comment Share on other sites More sharing options...
WME Posted July 13, 2016 Share Posted July 13, 2016 Gotta find the isolator!!!!! Follow the big wires from the batteries Possibilites are a shorted isolator and or a dead coach battery. Small steps grasshopper.. Quote Link to comment Share on other sites More sharing options...
84TOYRV Posted July 13, 2016 Author Share Posted July 13, 2016 12 hours ago, WME said: Gotta find the isolator!!!!! Follow the big wires from the batteries Possibilites are a shorted isolator and or a dead coach battery. Small steps grasshopper.. The coach battery checked out at 95%, so is fully charged. Next, I will try to find the possible isolator short, after the t-storm passes. Thanx! ? Quote Link to comment Share on other sites More sharing options...
Maineah Posted July 13, 2016 Share Posted July 13, 2016 (edited) It's either wired wrong or toes up. Edited July 13, 2016 by Maineah Quote Link to comment Share on other sites More sharing options...
84TOYRV Posted July 14, 2016 Author Share Posted July 14, 2016 Does anyone have a link to a good replacement isolator? Also could you take a pic of it, to make sure that I'm looking at the right thing? I could take a pic, but I'm not sure about how to post it here..... ? Quote Link to comment Share on other sites More sharing options...
84TOYRV Posted July 14, 2016 Author Share Posted July 14, 2016 (edited) Edited July 14, 2016 by 84TOYRV Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 14, 2016 Share Posted July 14, 2016 In the picture you posted, the isolation relay is the device in the top left. The wire connected to the middle of it, is the wire that energizes the isolation relay and connects the house side to the truck side. The relay would either have to be shorted internally, (meaning the two are connected no matter if the center wire is energized or not ) or the middle wire is connected to a power source. I do not see where it goes from that terminal. A few hand tools and a test light would go a long way in figuring it out. Here is a picture of a relay kind of like I used though not sure it would help Quote Link to comment Share on other sites More sharing options...
84TOYRV Posted July 14, 2016 Author Share Posted July 14, 2016 30 minutes ago, Back East Don said: In the picture you posted, the isolation relay is the device in the top left. The wire connected to the middle of it, is the wire that energizes the isolation relay and connects the house side to the truck side. The relay would either have to be shorted internally, (meaning the two are connected no matter if the center wire is energized or not ) or the middle wire is connected to a power source. I do not see where it goes from that terminal. A few hand tools and a test light would go a long way in figuring it out. Here is a picture of a relay kind of like I used though not sure it would help The middle red wire goes to the coil w/igniter. Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 14, 2016 Share Posted July 14, 2016 (edited) 50 minutes ago, 84TOYRV said: The middle red wire goes to the coil w/igniter. The question is, do you have a test light or voltage meter? If that wire goes to the coil, it is connected via the ignition key and the relay should only work when the key is turned on. With a test light, you can first remove the battery connection at the right side of the relay. Make sure to tape up the wire you removed as it would be live. With the test light lead clipped to ground, place the probe end to the stud you removed the wire from. There should be no voltage there, meaning the lamp in the test light would not come on. If there the test light indicates voltage by coming on, and there is no voltage at the middle terminal, the relay is shorted and is toast. Simply search for a "12 volt battery isolation relay" If there is no voltage at that terminal it means your battery discharge problem is elsewhere. Edited July 14, 2016 by Back East Don Quote Link to comment Share on other sites More sharing options...
WME Posted July 14, 2016 Share Posted July 14, 2016 There are not enough wires on your isolator. There should 2 large wires on one terminal. There should be a charge wire from alternator and a wire to the truck battery on one terminal, the other should be a large wire to the house battery. Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 14, 2016 Share Posted July 14, 2016 5 minutes ago, WME said: There are not enough wires on your isolator. There should 2 large wires on one terminal. There should be a charge wire from alternator and a wire to the truck battery on one terminal, the other should be a large wire to the house battery. Not necessarily. If the alternator wire is connected to the truck battery along with the relay, it is the same circuit. You might be able to argue it will charge better but marginally. Like a lot of these, the wire gauge is more the limiting factor. Quote Link to comment Share on other sites More sharing options...
WME Posted July 14, 2016 Share Posted July 14, 2016 IF???? Follow all the wires, where does the large wire from the alternator go? Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 14, 2016 Share Posted July 14, 2016 11 minutes ago, WME said: IF???? Follow all the wires, where does the large wire from the alternator go? I am a little fuzzy on the description of problem and how they are troubleshooting. They have not said the battery is not charging just that it is discharging. Perhaps that is built in to how they are describing the problem. Definitely need a better dialog and description. If as they say, if they disconnect the house battery that doesn't disconnect the isolator so the truck battery would feed the house but should be only when the key is in. If when they disconnected the truck battery and everything goes dead that would be odd if the house battery is connected back up. The question is, does the battery charge when the engine is running? Then some clarification is in order of what is connected and disconnected when testing. I'm not leaning on anything at this point and don't have enough to point in any direction. Quote Link to comment Share on other sites More sharing options...
WME Posted July 14, 2016 Share Posted July 14, 2016 With out the facts a guess would be, it seem to be very possible the house battery is not connected to anything. Which is why your asking about a volt meter and I'm saying follow the big wires. Its gotta be simple. Quote Link to comment Share on other sites More sharing options...
Maineah Posted July 14, 2016 Share Posted July 14, 2016 If it is a relay type isolator it does not have an alternator wire it is directly connected to the truck battery. Only the solid state ones do. The relay you have pictured probably does not work because one of the small terminals is not connected. That however does not explain why it is killing your truck battery. Follow the two heavy black wires and see where they go. If you disconnected the - terminal at the coach battery it may explain the problem. Remove the coach battery wire from the isolater check the voltage on the terminal the wire was removed from the voltage should be nil (key off). If it's not the relay is toes up. That's a start see what you get. Quote Link to comment Share on other sites More sharing options...
zero Posted July 15, 2016 Share Posted July 15, 2016 Just a guess - but it looks like your RV was wired with a AMC or Ford starter-relay to use as an isolation relay. If true, it only needs that one small terminal to energize. Again, if true - the other small terminal will be marked with the letter "R." That "R" is for an ignition resister bypass and is not needed to be hooked to anything for the relay to work. Again, if I am correct - the large (10 gauge wire?) I marked "A" should be hooked to the positive terminal of the engine-cranking battery. "B" is the small terminal on the relay that gets POS power whenever the ignition key is "on." It is likely marked "S" for "start." "C" is the unused terminal that should be marked "R" for resistor-bypass. "D" looks like another 10 gauge wire that runs to "E", a 30 amp circuit-breaker. From there - wire marked "F" gets connected to the POS terminal on the "house" battery. There are two different types of relays that have two small terminals and two large terminals. On one - used for starter-relays - they can be energized with just the one small terminal and are self-grounding. On the other type - one small terminal is for POS power and the other small terminal is for NEG power - to get energize. Quote Link to comment Share on other sites More sharing options...
zero Posted July 15, 2016 Share Posted July 15, 2016 One added comment. Some of the relays with two small terminals that only need one hooked to anything to energize - vary with the letter marks. On all I know of, "S" is the one that needs POS power to energize and are self-grounding. The other unused terminal can be marked "R" for "resistor bypass for ignition", or "I" for "ignition resistor." Like in these photos used on 60s-70s Fords and Jeeps. Quote Link to comment Share on other sites More sharing options...
jjrbus Posted July 15, 2016 Share Posted July 15, 2016 17 hours ago, 84TOYRV said: Does anyone have a link to a good replacement isolator? Also could you take a pic of it, to make sure that I'm looking at the right thing? I could take a pic, but I'm not sure about how to post it here..... ? This is the most user friendly RV site on the net for posting pictures at least from a camera, I am not sure from a phone. It would be in your best interest to spend a little time learning how to post them and may save you endless grief. HTH Jim Quote Link to comment Share on other sites More sharing options...
Maineah Posted July 15, 2016 Share Posted July 15, 2016 A 4 terminal relay was also used as a start inhibit so it could not be started in gear (a grounded connection) both types were not constant duty relays and would soon burn up.. Quote Link to comment Share on other sites More sharing options...
linda s Posted July 15, 2016 Share Posted July 15, 2016 I don't know if all those wires are good or not or if they terminate in the correct places but it's hooked up exactly the same as my Sunrader except for mine has a ground wire running to the empty pole on the front. Here's a replacement. Since nothing is attached to your 4th pole I am only showing the 3 pole isolator. The 4 pole is available here too. Linda S https://www.amazon.com/Tekonsha-7000-Terminal-Battery-Isolator/dp/B0002UHVYQ Quote Link to comment Share on other sites More sharing options...
Maineah Posted July 15, 2016 Share Posted July 15, 2016 Yep that will work. Quote Link to comment Share on other sites More sharing options...
84TOYRV Posted July 18, 2016 Author Share Posted July 18, 2016 On Thursday, July 14, 2016 at 11:53 AM, Back East Don said: In the picture you posted, the isolation relay is the device in the top left. The wire connected to the middle of it, is the wire that energizes the isolation relay and connects the house side to the truck side. The relay would either have to be shorted internally, (meaning the two are connected no matter if the center wire is energized or not ) or the middle wire is connected to a power source. I do not see where it goes from that terminal. A few hand tools and a test light would go a long way in figuring it out. Here is a picture of a relay kind of like I used though not sure it would help Thanks to all. Lots of ideas. I will be checking it out, further , within the next few days. I have been busy, lately, with other things. The middle red wire goes to the coil w/igniter. Quote Link to comment Share on other sites More sharing options...
WME Posted July 18, 2016 Share Posted July 18, 2016 GET a Voltmeter. The center red wire should go to a switched 12v source (key on). There is a second auto CB on the far right side of your picture, where does it go.? Quote Link to comment Share on other sites More sharing options...
84TOYRV Posted July 18, 2016 Author Share Posted July 18, 2016 I'll check it out tomorrow and get back with an answer. Quote Link to comment Share on other sites More sharing options...
Maineah Posted July 18, 2016 Share Posted July 18, 2016 The small signal wire is generally connected to the wiper wiring it's close by and fused. Many local auto parts stores carry continuous duty high current relays if indeed it's bad but replacing parts until some thing is fixed is not real cost effective. Quote Link to comment Share on other sites More sharing options...
84TOYRV Posted July 18, 2016 Author Share Posted July 18, 2016 On Thursday, July 14, 2016 at 4:27 PM, Maineah said: If it is a relay type isolator it does not have an alternator wire it is directly connected to the truck battery. Only the solid state ones do. The relay you have pictured probably does not work because one of the small terminals is not connected. That however does not explain why it is killing your truck battery. Follow the two heavy black wires and see where they go. If you disconnected the - terminal at the coach battery it may explain the problem. Remove the coach battery wire from the isolater check the voltage on the terminal the wire was removed from the voltage should be nil (key off). If it's not the relay is toes up. That's a start see what you get. I'll check it out tomorrow and get back with an answer. ok. We checked the voltage on the coach battery terminal. It registered 12 volts. So the isolater relay is toast? Both batteries were charged 2 weeks ago. Both batteries registered 6 volts, when we checked today. I'd like to know where all that power goes. A big short somewhere? My hubby & I are trying to figure it out. All coach lights, pump, ect.. runs off the truck battery only. But nothing seemed to run off of the coach battery, when we had it charged to 95%, but yet it's losing charge. Btw this coach battery is only 2 yrs old. It is an AGM type, but would this make a difference? The truck battery was replaced last year. We keep it on a battery tender on the truck battery 8 months of the year. Maybe the coach battery was toast, when I first plugged it in a couple of months ago..... ? Quote Link to comment Share on other sites More sharing options...
WME Posted July 19, 2016 Share Posted July 19, 2016 12 v ain't gonna cut it!! http://nortonsafe.search.ask.com/search?&q=rv+isolator+solenoid+diagram&chn=1000&geo=US&locale=en_US&o=APN11912&prt=NSBU&ver=22&ctype=pictures&tpr=2&ts=1468896947729&imgs=1p&filter=on&imgDetail=true OK engine running 13.5v + at the alternator post, 13.5v + at the truck battery. 13v.5v+ at the input to the solenoid. 13v+ at the solenoid output. 13v+ at the in and out to the CB. 13v+ at the coach battery. All voltages are to a GOOD ground. Quote Link to comment Share on other sites More sharing options...
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