Unknown Solenoid

Topic: Unknown Solenoid (Read 1386 times) previous topic - next topic

Unknown Solenoid

May 28, 2013, 08:35:40 am

I know I should know the answer to this and it may be too early in the morning but I don't recall what the extra, outboard solenoid behind my driver wheel is for. I will post a photo later if required.

For those who have a U300, the isolater, several relays and two solenoids are attached to a metal plate behind the drivers rear wheel. I know the inboard solenoid is the Boost Switch but what is the outboard solenoid for? I am replacing them both tomorrow but I would like to know what it does and what switch activates it.

Re: Unknown Solenoid

Reply #1 – May 28, 2013, 09:30:20 am

On mine it's for the engine start at the back end.

Re: Unknown Solenoid

Reply #2 – May 28, 2013, 10:46:22 am

Kent,

One is the boost and the other is the aux starter solenoid and is tied to the starter button in the engine compartment. Make sure they don't talk you into older model solenoid. Newest solenoid part number is here in old posts. Either one of the small terminals goes to ground and the other hot. Makes no difference.

Pierce

Re: Unknown Solenoid

Reply #3 – May 28, 2013, 12:49:26 pm

I know I'm gonna regret asking this, but why would anyone start their engine from the back unless they've installed an oil pressure gauge back there where it can be seen? I watched a guy start one from the back for a moment, then shut it off, I guess just to demonstrate that he had a rear start switch. He didn't have any oil pressure gauge I could see and he didn't even check the oil before he started it. His engine had probably been sitting cold for several days. I never take risks like that unless it's an emergency or something... but that's just me

Re: Unknown Solenoid

Reply #4 – May 28, 2013, 03:54:37 pm

Scott, There is an oil pressure GAUGE at the rear start panel, on mine it is a RED lite, if it stays on you have no oil pressure. You might be surprised at the times you would want to start from the rear when working on the coach. Just another convenience that FT adds to its coaches.
Gary B

Re: Unknown Solenoid

Reply #5 – May 28, 2013, 04:47:43 pm

When the fuel lift pump went out on my 1998 U270 last week, the tech spent over 1/2hr starting it from the rear. Which required a portable charger to keep the batteries up. After seeing how hard it was to get started, I do not want to ever run out of fuel.

Re: Unknown Solenoid

Reply #6 – May 28, 2013, 04:51:31 pm

Scott,

I use the rear switch all the time. Good if adjusting the belt tensioner alignment, after replacing the AC belt, after replacing filters to check for leaks, etc., etc. A decent mechanic can even detect low compression by listening to it crank over when cold. My bus had the same switch and I also used it frequently.

Pierce

Re: Unknown Solenoid

Reply #7 – May 28, 2013, 06:20:54 pm

The DDEC will shut the engine down if there's no oil pressure or not enough. It's more vigilant than any driver.

Re: Unknown Solenoid

Reply #8 – May 28, 2013, 06:24:14 pm

Quote from: Kent Speers – May 28, 2013, 08:35:40 am

I know I should know the answer to this and it may be too early in the morning but I don't recall what the extra, outboard solenoid behind my driver wheel is for. I will post a photo later if required.

For those who have a U300, the isolater, several relays and two solenoids are attached to a metal plate behind the drivers rear wheel. I know the inboard solenoid is the Boost Switch but what is the outboard solenoid for? I am replacing them both tomorrow but I would like to know what it does and what switch activates it.

I know I should know the answer to this ... but if they are working, why are you replacing them?

Re: Unknown Solenoid

Reply #9 – May 28, 2013, 06:31:09 pm

Excellent question Carol! The problem lies in the location of the panel. It gets some road spray and all the components are exposed to the elements. Photos of some panels look like they are under a pier in San Francisco bay. There is not even a cover for protection. This is why Brett moved everything up to a better spot. The problem is also on all GVs, not just U300s. Kent is making a smart PM move and will have one less "monster under the bed" to grab at his ankles this summer.

Pierce

Re: Unknown Solenoid

Reply #10 – May 28, 2013, 07:14:58 pm

My coach doesn't have the rear start switch, but I think it does have the extra solenoid already installed for it if I remember correctly. Mine doesn't have an oil pressure gauge in the back. I've seen a couple of coaches like mine with the rear start switch but none of them had an oil pressure gauge back there that I saw. My dad was a diesel mechanic and I have a bunch of his tools, including a heavy duty remote start switch that he used to crank diesels. I think I'm carrying it around with me in the cargo bay actually, but I've never needed it. I don't even start the generator or my motorcycle without first checking the oil. There's no way I'd start my coach from the back without checking the oil and watching the pressure gauge for at least few seconds. I guess I'm more paranoid than you guys.

Re: Unknown Solenoid

Reply #11 – May 28, 2013, 08:48:58 pm

Quote from: Carol Savournin – May 28, 2013, 06:24:14 pm

I know I should know the answer to this ... but if they are working, why are you replacing them??

Carol knows me to well. My favorite saying is "If it ain't broke don't fix it and if it is broke you cain't hurt it". My boost switch is broke. "It don't work no mo". I did order two Cole Hersee, 24213's. I was going to replace both but the Rear Start Switch works just fine so I will keep the extra switch for future use.

Thanks for the info on the outboard switch. I just couldn't' remember what it was for.

Re: Unknown Solenoid

Reply #12 – May 28, 2013, 11:24:19 pm

As others have said one solenoid is boost.

The other solenoid closes whenever the ignition key is turned to start (if transmission is in neutral), sending start battery bank current to the starter solenoid.

And is also used by the 'controversial' rear start.

Changing these solenoids are always a good idea as terminals get corroded and boost solenoid gets burnt points from high amperage flowing during engine start.

Re: Unknown Solenoid

Reply #13 – May 28, 2013, 11:30:31 pm

As far as using the rear start goes, I've used it after a purge of the fuel system to ensure the engine will start.
I've also used it when adjusting the voltage regulator and adding freon.. Turn the ign key on, go to the back and flip the switch to 'on', then press the start button.

When you are down, flip the switch back to off - the engine will still run, then go up front and turn the ignition off.

There are times when it comes in handy.

Re: Unknown Solenoid

Reply #14 – May 29, 2013, 12:35:21 am

Kent,

I replaced mine last month. Cole hersee 24213 and should be a stock item at your local O'reiley's for $65. I was starting to have intermittent delays when turning the key on and mine was 20 years old and very corroded. No problems since I replaced it and I also replaced the same one for the boost solenoid last summer. The new one has two terminals in the front and be sure to run a ground wire from one of them as recommended by Gary B. Hopefully, I'm good for another 20 years.

Jerry

Re: Unknown Solenoid

Reply #15 – May 29, 2013, 09:13:14 am

Quote from: Barry & Cindy – May 28, 2013, 11:24:19 pm

As others have said one solenoid is boost.

The other solenoid closes whenever the ignition key is turned to start (if transmission is in neutral), sending start battery bank current to the starter solenoid.

Correct, both the "aux" solonoid (on the isolator board), the "ign" solonoid (in the dash), and the N/S (neutral start) circuit are required to operate to get the engine starter solonoid to fire.

Quote from: coastprt – May 29, 2013, 12:35:21 am

Kent,

Hopefully, I'm good for another 20 years.

Jerry

That's what I thought but after just a few months the Cole Hersey unit died. I had another one and knew right where to go. I posted my results about it at the time. My original "aux" sol is still in place and won't get replaced unless it fails. I put penetrating oil on all of the terminals on the aux board and then applied some grease over them to keep the oiled and ready to come off when the time comes.
Rick

Re: Unknown Solenoid

Reply #16 – May 29, 2013, 09:50:02 am

Quote from: Rick – May 29, 2013, 09:13:14 am

That's what I thought but after just a few months the Cole Hersey unit died. I had another one and knew right where to go. I posted my results about it at the time. My original "aux" sol is still in place and won't get replaced unless it fails. I put penetrating oil on all of the terminals on the aux board and then applied some grease over them to keep the oiled and ready to come off when the time comes.
Rick

Thanks Rick,

I guess I better keep a few spares handy. Says a lot about the quality of parts now and 20 years ago.

Jerry

Re: Unknown Solenoid

Reply #17 – May 29, 2013, 10:16:32 am

A lot of members have had trouble with the CH 24123 and have replaced it with a solid state solenoid (for more $$). Here is a quote from Cole-Hersee: "This part number replaces #24143. 24123 had silver contacts; the replacement 24213 has superior silver tungsten carbide contacts, and is electrically identical."

Seems they have been upgraded several times and hopefully will provide better service now.

Pierce

Re: Unknown Solenoid

Reply #18 – May 29, 2013, 10:55:13 am

bought two of the 24123 just now from Ryder Fleet sales for $41.95 each plus $7.95 shipping

Re: Unknown Solenoid

Reply #19 – May 29, 2013, 05:03:16 pm

While installing my me CH 24213, I also installed the Ultra Trik L Start charger. Hopefully I will not need to leave my boost switch on for any length of time to charge the starting batteries thereby eliminating the "continuous use" that tends to burn up the contacts of the solenoid more frequently.

Re: Unknown Solenoid

Reply #20 – May 29, 2013, 09:36:45 pm

These solenoids are easily disassembled in a minute or less, the heavy copper contacts can be dressed to new condition as long as they have not eroded away. If the coil is good, it's then as good as new.

Chuck

Re: Unknown Solenoid

Reply #21 – May 30, 2013, 06:39:40 am

Kent I think the other one is the starter solenoid.

Re: Unknown Solenoid

Reply #22 – May 30, 2013, 08:45:36 am

Quote from: Kent Speers – May 29, 2013, 05:03:16 pm

While installing my me CH 24213, I also installed the Ultra Trik L Start charger. Hopefully I will not need to leave my boost switch on for any length of time to charge the starting batteries thereby eliminating the "continuous use" that tends to burn up the contacts of the solenoid more frequently.

Kent,
It is the arcing that occurs when making and breaking (switching on and off) that can damage the contact plate and contact flats on the bolts. My last failure of one required only an pencil eraser to clean some carbon off of the plate. The plate nor the bolts were pitted, just carboned over enough so as not allow connection.

Re: Unknown Solenoid

Reply #23 – May 30, 2013, 06:00:05 pm

I just completed the change out of the Boost Solenoid. What was previously on the coach was not a Cole Hersee and was not nearly as heavy duty as the 24213. It used metric nuts not SAE like the Cole Hersee. My guess is someone had put a much lower quality, lower amperage solenoid on and probably not even one made for continuous duty. It didn't weigh half of the weight of the new CH 24213. The click of the 24213 is also twice as loud when making the connection. The old one was so fried that the posts were both floppy loose. I kept the extra one for future use and did not change the starting solenoid since it was still working just fine.

As mentioned, since installing the Ultra Trik L Start I doubt that I will need to use the boost switch very much. The starting batteries are staying at 13.0 to 13.1 volts most of the time when I'm plugged in to AC.

Re: Unknown Solenoid

Reply #24 – May 31, 2013, 06:23:45 pm

Be careful of the new replacements. I ordered one made in China and it was junk.

As Chuck posted, these relays are repairable. . I did open heart surgery on my boost relay. Used emery cloth to brighten up the copper. To stake the cap back on I carefully used a chisel to stake the cap about every quarter inch. My boost relay is on the 12v distribution panel in the battery bay.

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