Battery Isolator Solenoid Relay Issue - Works but only with boost switch

bizee · 10-25-2015, 12:53 AM

When I bought our 2001 Itasca a couple years ago I eventually learned that the coach batteries should be charged by the alternator when the engine is running. Ours wasn't so we would run out of juice using the inverter and could only get the batteries charged up on shore or with the gennie.

Once I realized this I started looking into it more and found out about the relay solenoid. The battery boost switch would make it pop, but it wouldn't join the coach and chassis cables. I later determined this was because of oxidized contacts in the relay when I dissected it at a later date.

Anyways, when it wasn't working I went out and bought a replacement. It was identical to the one installed (3 post model... the chassis cable on the left post, the boost cable in the middle post and coach cable on the right post).

I replaced it and it was working... when I pressed the boost switch (engine off) it would join the coach and chassis batteries as confirmed by ohmmeter (battery cables disconnected) and also using a voltmeter (with cables connected, both legs measured the same voltage as alternator when engine running). Not only that, but you can tell just by the change in the noise in the alternator and how the coach lights brighten when you hold the boost switch when the engine it running. I also was able to verify it was working properly whereby when the engine started the relay would automatically engage thereby charging the coach batteries from the alternator.

It was auto engaging when the engine started for at least a day, because our very low house batteries were full after several hours of driving to our next stop. We ran them down pretty low that evening and drove off to the next stop. After a a few hours on the road we stopped and I checked our coach voltage to see if they were full and they were still empty, so the relay was clearly not automatically energizing with the engine running now. I tested the relay solenoid and confirmed it was not. However, it would energize if the boost switch was depressed, so the solenoid was working, but only with the boost switch.

And this is where I'm at now... I'm trying to make sure my understanding of how this solenoid works first to make sure I'm not barking up the wrong tree...

The way I understand it (based on visual inspection of the guts of my old one), is the left and right post are nothing but contacts to join the circuit. The power applied on those posts is relevant to the actual opening and closing of the solenoid. It is the center post that carries the 12v signal that actually energizes it (closes the circuit). That yellow wire goes into a wiring harness which I assume goes to alternator and that on the same wire there is a lead tapped into that goes to the boost switch which goes to either the coach or chassis battery.

I've looked at the Winnie diagrams to no avail. I can see the wire (label "LR") in the diagrams but the trail seems to end at a wiring harness. I feel like there has to be a fuse between the alternator and the signal wire. I've checked all the blade fuses (big and small) I could find (driver side under dash console and in engine bay box) and all are good.

Can anyone shed some light on how to diagnose why I am not getting 12v on the solenoid signal wire when the engine is running and only when I press the boost button?

For reference... my solenoid is wired the following way:
Left Post (+ Wire to Chassis Battery, Black wire which I think goes to alternator)
Center Post (Yellow wire - battery boost activates this but is not activated when engine is running)
Right Post (+ Wire to Coach Battery, + Wire to Disconnect Relay, a different Yellow Wire going to a harness and not sure what it does)

Thanks!

bizee · 10-25-2015, 01:24 AM

I started searching around with different keywords and have turned up some info that further confuses things even more.

I read a post where someone said they thought the solenoid on Winnies were only wired to the boost switch until 2006. Of course that could be inaccurate, but either way when I replaced the old solenoid that had the bad contacts I verified it was activating with both with the switch and on its own by starting the motor.

Others had suggested it could be wired to the AUX (ignition) as opposed to the alternator. Again, I have no idea since I can't make sense of the wiring diagram but from what I can tell that might be the case. I can't remember if it was popping on when I flipped the key to ignition position or when I actually started it, but it either way it was definitely popping on. I remember checking it couple times even on the drive we took that day and when the engine was running it would read the same voltage (about 13.6v) on both coach and chassis, so they were definitely joined.

I'm hoping someone else has been down this same road and can tell me where to look and whether the solenoid gets it power from the alternator or AUX because I suspect a wire may have come loose or a fuse or relay somewhere is bad.

bizee · 10-25-2015, 01:42 AM

Very odd... I was testing it again and decided to switch the "Radio Power" switch (House vs Engine) and it started working. But what's weird is I switched it back and it is still working, so it is probably more of coincidence. Either way, it is working but I'm still not sure why, or why it wasn't, lol, but I'll take the win.

I guess the problem is solved for now. It's just odd because on the last trip it wasn't working at all.

Monacoach · 10-25-2015, 06:18 AM

On our coach there is a circuit board that controlls the opening and closing of the isolator solonoid. This circuit board kept burning out on me so when ever the engine was running ,
the house batteries would not receive a charge. After 3 trips to the mechanic where they would simply replace the circuit board without investigating why they were burning out, i decided to use the boost switch permanently. I start the engine let it run for a few minutes to make sure the chassis voltage is where it should be then depress the boost switch and hold it in position with a beer cap.

skigramp · 10-25-2015, 07:07 AM

Monacoach

hold it in position with a beer cap

you are my kind of fixit guy ... why didn't I think of that

grtharris · 10-25-2015, 09:13 AM

bizee, what is the model of your coach?

jerichorick · 10-25-2015, 10:26 AM

Hi Bizee. Sorry to hear of your problem. Yes, the coach model would be very helpful. Go to the Winnebago site and pull the wiring diagram for your coach, if you have not already.

One caution about the BIRD solenoid. Though the case and terminals of the replacement may look the same on two units side by side it does not mean they are the same on the inside. What you need is a continuous duty, high current rating, silver contact replacement. I don't know the full spec on this one but it has a good rating: http://www.amazon.com/PAC-PAC-200-20...lenoid+battery.

If it will fit in the space you have use it. The electrons don't care. lol.

Rick Y

YC1 · 10-25-2015, 10:42 AM

Proverbial intermittent. It appears you have two control lines. The boost which has been working fine and an ignition control that has been on and off again. Since you didn't find a fuse blown and it is now working it is likely a connection that you have exercised by moving wires and things about. These can be frustrating but you have excellent information when it acts up again.

You can buy a simple fox and hound and connect it to the solenoid control wire. Then trace the wires back with the fox. One should lead you to the aux switch and the other to some ignition wire or to a loose fuse block connection.

If you have round fuses it is easy for one end of a fuse holder to loose contact. You might want to turn the ignition to the run position but not start the vehicle. See if the solenoid is activated. If so, start pulling fuses until it shuts off. At that stage you at least know the fuse that controls it.

jerichorick · 10-26-2015, 11:36 AM

So often we have electrical issues that require the wiring schematic to make the problem location more clear. Unfortunately Winnebago stopped providing this information after model year 2009 in their Reference section of their website. I have just contacted them about this problem. Let's see what response we get back.

Rick Y

bizee · 10-26-2015, 03:32 PM

It is an Itasca Suncruiser... but it is fixed now. But I want to add some more info for people who may have this problem and find this thread.

I actually did find a fuse blown that I replaced, but I didn't think anything of it since it was unrelated (so I thought) to solenoid circuit. I later realized that might have been the reason it started working and it is.

Under the dash console on the left side there are two fuse boxes. One is a standard Ford fusebox, the other is added on by Winnie. In the Winnie box there is a 15 amp fuse labeled "Coach Heater". This is supposed to be linked to the 3 way switch (low, high, off) on the dash that directs engine heat through your furnace vents when driving. It has never worked and everytime I try to turn it on it pops the fuse. I suspect a seized fan or something, but I've never needed it enough to look into it.

Apparently, at least on mine, they are powering this charge control circuit that someone else mentioned above. Or however it works, the 12v that would normally be sent to the solenoid is traveling through the fuse.

jerichorick · 10-27-2015, 09:49 AM

Quote:

Originally Posted by bizee

It is an Itasca Suncruiser... but it is fixed now. But I want to add some more info for people who may have this problem and find this thread.

I actually did find a fuse blown that I replaced, but I didn't think anything of it since it was unrelated (so I thought) to solenoid circuit. I later realized that might have been the reason it started working and it is.

Under the dash console on the left side there are two fuse boxes. One is a standard Ford fusebox, the other is added on by Winnie. In the Winnie box there is a 15 amp fuse labeled "Coach Heater". This is supposed to be linked to the 3 way switch (low, high, off) on the dash that directs engine heat through your furnace vents when driving. It has never worked and everytime I try to turn it on it pops the fuse. I suspect a seized fan or something, but I've never needed it enough to look into it.

Apparently, at least on mine, they are powering this charge control circuit that someone else mentioned above. Or however it works, the 12v that would normally be sent to the solenoid is traveling through the fuse.

"It is an Itasca Suncruiser". I have a Itasca Meridian but that tells the readers little if they don't know the year and model. The 40U first appeared in 2011 and is no longer produced. So, when I ask for help I hope the reader will view my signature to understand my question more clearly.

I am glad that it was only a fuse and that you found it. I wonder what made the fuse operate in the first place?

Happy trails,
Rick Y