Replacing Trombetta booster solenoid with Cole Hersee

[mojack]

I'm new to the forum and hoping to learn from those who have more experience in RVing. Thanks in advance for any suggestions, help and advice.


I have a 2018 Winnebago ERA RV and the Trombetta booster solenoid is bad. Following advice on this forum and others, I'm replacing it with a Cole Hersee 24213 and I need help with the wiring. On the old solenoid there was a yellow and white wire paired together and connected to the small pole. There was a diode on the end of the white wire where it was connected with the yellow wire. I'm guessing the yellow wire is the D+ wire and the white wire is connect to another white wire and both are apparently ground wires that are bolted to the seat frame.



My question is with the 4 post Cole Hersee, do I connect the yellow and white combo wire to one of the small posts and put a separate ground wire on the other small post? Or do I separate the combined yellow and white wire and put the yellow on one small post and the white on the other small post? Thanks

[bigb]

Originally Posted by mojack

I'm new to the forum and hoping to learn from those who have more experience in RVing. Thanks in advance for any suggestions, help and advice.


I have a 2018 Winnebago ERA RV and the Trombetta booster solenoid is bad. Following advice on this forum and others, I'm replacing it with a Cole Hersee 24213 and I need help with the wiring. On the old solenoid there was a yellow and white wire paired together and connected to the small pole. There was a diode on the end of the white wire where it was connected with the yellow wire. I'm guessing the yellow wire is the D+ wire and the white wire is connect to another white wire and both are apparently ground wires that are bolted to the seat frame.



My question is with the 4 post Cole Hersee, do I connect the yellow and white combo wire to one of the small posts and put a separate ground wire on the other small post? Or do I separate the combined yellow and white wire and put the yellow on one small post and the white on the other small post? Thanks

Look closer at those 2 wires, I think you'll find they are not grounded, they are the positive trigger wires for the relay coil.
The two wires (yellow and white with diode) go on one coil terminal and you make up a second jumper to go from one of the mounting screws to the other coil terminal. The coil terminals are interchangeable so it doesn't matter which one is grounded and which one is positive. On mine there was a pair of white ground wires behind one of the mounting screws, I just left them there and added a jumper. This assumes your coil is mounted to metal, if it is mounted to wood then run a jumper from a metal area.

[mojack]

I believe the yellow wire is the positive wire for the relay coil, and the white wire with the diode that is paired with the yellow wire is grounded with a bolt to the seat frame. Do I leave them paired and attach it to one of the coil terminals and make up a second jumper to to from the other coil terminal to another bolt on the seat frame (or some other grounding source)?

[bigb]

Originally Posted by mojack

I believe the yellow wire is the positive wire for the relay coil, and the white wire with the diode that is paired with the yellow wire is grounded with a bolt to the seat frame. Do I leave them paired and attach it to one of the coil terminals and make up a second jumper to to from the other coil terminal to another bolt on the seat frame (or some other grounding source)?

Yes that's it, you can pick up the ground anywhere, it's just for the coil and the current draw is in the milliamps.

[mojack]

Thanks Brian

[bigb]

I didn't realize the wire with the diode was grounded, mine was such a rats nest I couldn't see where they both went. That explains why when I cut it in an attempt to disable the solenoid it still worked. Makes total sense now, Winnie uses white for ground/negative.

[bigb]

One more thing I learned, the instructions for the Cole Hersee (which do not come with it) recommend installing with the printed cap down, not up like the Trombetta. I'm guessing it will make little difference but when mounted with the cap down, and de-energized, the plunger contact naturally drops downward instead of relying on the spring to push it upwards. I mounted mine cap down but it was kind of a pain to make the wires all reach as a couple are only a few inches long and very fat.

[mojack]

I thought about separating the white wire with the diode from the yellow wire, and putting the yellow wire on one relay terminal and the white wire with the diode on the other relay terminal. But, I don't if that would affect the booster function that allows the house batteries to boost the starter battery.

[bigb]

Originally Posted by mojack

I thought about separating the white wire with the diode from the yellow wire, and putting the yellow wire on one relay terminal and the white wire with the diode on the other relay terminal. But, I don't if that would affect the booster function that allows the house batteries to boost the starter battery.

No, don't do that. putting them both on one terminal and grounding the other is basically the same as the factory setup

[bigb]

Here is where I saw to install it with the printed cap down, you can see that this way when at rest the plunger is naturally inclined to drop down.
https://www.colehersee.com.au/produc...duty-solenoid/ It's an Australian web site, I didn't see that info anywhere else.

[mojack]

Thanks for pointing that out. I haven't seen that previously.

[Morich]

I'm late to the discussion but there seems to be something major missing?

If one wire is grounded under the seat and you add it to the same post as the 12Volt signal coming down from the front, isn't that going to blow a fuse if you tie battery and ground directly together?

I would want to check the wiring carefully as it seems way odd. The wires should be stamped with an Id on the ends, LR being the power and FM being the ground.

This is the chart to ID small wiring:
https://www.winnebago.com/Files/File...ical_guide.pdf
Many Winnebago do not have the FM wire as the ground for the solenoid coil is just provided by the mounting screws of the solenoid.
All the ERA RV of that year seem to show FM should be laid on the mounting screw, not the small terminal.
Basic idea is that power comes down on LR, goes through the solenoid coil to operate it and then to ground.
If the small lug is on one end of the coil and we lay both battery and ground there, how can the coil operate?

Just not making sense from here! If this is the way the old solenoid was wired, that might explain why the solenoid did not work? Sometimes when we are following work done by somebody else we need to be extra careful!

The drawings for this year of ERA are really pretty poor quality as they tend to not connect wires to lugs but just stop in mid air!
I made a few corrections to show the wires actually stop at lugs, not mid air!

See if that makes some sense of what you see?

[mojack]

I'm a novice when it comes to RV wiring but I know enough about electrical in general to recognize that the what you're saying about the signal wire and ground going to the same post makes sense. I checked but haven't found any blown fuses. The yellow wire that goes to the small terminal is labeled LR, but the white wire with diode paired with it apparently is not original as it is labeled GDN (and it is paired with another white wire that is labeled FM of unknown source) and both are grounded to the seat base. Since I don't know the source of the FM wire that is paired with the GDN wire I don't think I can simply disconnect them from the base. I suppose I could cut the GDN wire and then test if the solenoid works.

Jack
2018 Winnebago ERA on 2016 Sprinter

[bigb]

Mine has the same setup, diode and all, only I didn't realize the white wire was grounded till I saw yours. Pretty sure the diode keeps it from short circuiting

[Morich]

Yes, we often get confusion along with a few bits of info we can trust, so we need to cross check when we can!

The FM definitely Id's as ground. I have found numerous Winnebago which use a three post version of this solenoid and has only the LR wire from the front bringing power in to the coil. On those the other end of the coil is connected to the metal of the frame inside where we don't see it.
On those we connect LR to one small lug and then when it is mounted, the metal case acts as ground to the RV body metal.

Having looked at older RV, way back, I found that was not the best system as any loosening or corrosion of that mounting screw lost the ground and the coil stopped working! Since ground is such a handy thing to find, I just ran a strap to ground at the mounting screw, kind of to double the ground connection.

I have not found what diodes might be meant to do in this plan. Maybe to reduce arcing at the switch?
The other wire ID of gdn is not listed on their ID chart. My first thought (as being a person paranoid about making mistakes) was that you might have meant gnd and that sounds like GROUND! But I find neither in the list, so got nowhere!

Two ideas that might be true? We know it has to have ground and the screw may be funky. So if you can test for ground on FM or know it goes to a bolt or ground under the seat, leaving it on the mounting at the solenoid seems to match.
Then we know that the coil has to have power come in from the front under two conditions. When we are pushing the boost switch for jumping a weak chassis battery and two when it gets power from a point some call "ignition hot" when the key is turned or engine running! That connection stays hot long enough to hold the solenoid and connect the two batteries together as we drive!
But if both go back to ground under the seat, I would leave them together as it looks like they are making double ground connections for whatever reason!

I've not worked on any of the Mercede RV but I read about a number of things that we have a hard time figuring!

[mojack]

Morich, you're right that the white wire is labelled GND (a typo in my previous post), but I still don't understand why it is paired with the LR wire. But, since that solenoid is not working, I'm planning to replace it with a Cole Hersee (4 post) solenoid. I plan to put the paired yellow and white wires on one small post and will add another wire as a ground. Thanks for your replies and help.

[bigb]

Here's an explanation for that grounded wire with the diode in case anyone is interested:

[Morich]

Thanks for the note. It makes sense but not one I would have thought of in a really long time. Helps hold down arcing at the switch or noise it might cause!

I'm not sure about how you are using "paired?
If you mean there are two together with the plastic making them a pair, I would look at them as two singles and use LR on the small center post and FM as the ground.
Whether to use a three post or four solenoid, I see no real difference as the three has the coil end attached inside the metal case and the four post uses the second small lug as ground instead of using the case.
So if we have a separate wire for ground we can put it on the second post or just lay it on the screw for mounting the solenoid as it then doubles the ground. One of the complaints on the three post type was that the mounting screw could get loose and you lost the ground to the solenoid.