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Topic: Changed out my 2 solenoids under the battery isolator, no start (Read 572 times) previous topic - next topic

Changed out my 2 solenoids under the battery isolator, no start

Ok. Changed out the 2 battery solenoids under the isolator today. Everything works in the coach but now The engine won't turn over. I have lights, ignition but no crank on the engine start mode. I transferred one at a time and floated the old taking one stud loose at a time so I don't think I mixed any wiring up. The new ones have 2 small 3/8 studs on top and the old one has one. Brad thinks they are the same, just one extra stud. On the solenoid towards the rear of the coach I have 12 volts on all 4 studs, On the one towards the front I have 12 volts on the rear main stud but nothing on the other 3. Any ideas what may be wrong? A defective solenoid?
1996 U295-36, Cummins 300hp, 8.3. Build number 4864. Vin number 1F97D536XTNO54271. Purchased October 31, 2019.

Re: Changed out my 2 solenoids under the battery isolator, no start

Reply #1 –
The new ones have 2 small 3/8 studs on top and the old one has one? Two small 3/8 studs. That is the size of the post on a group 31 start battery with 9/16 nuts. Are you describing the 10/32 posts with 3/8 nuts?
Scott

Re: Changed out my 2 solenoids under the battery isolator, no start

Reply #2 –
Your old solenoids grounded through the mounting bracket. You have to ground the other small stud on the new ones. It doesn't matter which one is hot and which one is ground.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
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Re: Changed out my 2 solenoids under the battery isolator, no start

Reply #3 –
Quote from: craneman –
Your old solenoids grounded through the mounting bracket. You have to ground the other small stud on the new ones. It doesn't matter which one is hot and which one is ground.

Correct.  Both should have the two large lugs for battery cables.

If the new one has two small terminals, one will be HOT-- use the hot wire from the old one.  You need to run a new wire from the other small terminal to any clean chassis ground. The same small-gauge wire as the hot wire is fine.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Changed out my 2 solenoids under the battery isolator, no start

Reply #4 –
Ok. The solenoids are Inteletech-7790000100. No instructions
1996 U295-36, Cummins 300hp, 8.3. Build number 4864. Vin number 1F97D536XTNO54271. Purchased October 31, 2019.

Re: Changed out my 2 solenoids under the battery isolator, no start

Reply #5 –
Quote from: dans96u295ft –
The solenoids are Inteletech-7790000100.
The solenoids you purchased are not continuous duty, and are rated for 100 Amp, which is OK but not ideal for this application.  The AUX START and BOOST solenoids live in a harsh environment and are critical to the operation of your coach.

Edit:  OP was advised by solenoid manufacturer that these are, indeed, continuous duty.  I was incorrect in my (above) statement.

Amazon.com: Intellitec 12 Volt Isolator Relay ~ 77-90000-100: Automotive

For a few dollars more, you can purchase a Cole Hersee 24213, which is the "gold standard" for this application.  Just something to keep in mind next time you are shopping for this item.  There are times that it pays to buy the best quality - this is one of them.

Amazon.com: Cole Hersee 24213 12V 200A Continuous Solenoid: Automotive
As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
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Sorento (or BOLT) on a Kar Kaddy SS
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Re: Changed out my 2 solenoids under the battery isolator, no start

Reply #6 –
Thanks Chuck. I'll reorder and I agree. This was FT's replacement idea
1996 U295-36, Cummins 300hp, 8.3. Build number 4864. Vin number 1F97D536XTNO54271. Purchased October 31, 2019.

Re: Changed out my 2 solenoids under the battery isolator, no start

Reply #7 –
Yes, on a solenoid, two things are important:

Constant duty-- meaning it was designed to be able to operate for long periods of time (vs intermittent which are not).

Bigger is better.  Oversizing (i.e. higher amp rating) has contacts with more surface area and/or better material. 
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Changed out my 2 solenoids under the battery isolator, no start

Reply #8 –
I wonder why FT would ship me anything less? I'll order the HD ones and thanks again
1996 U295-36, Cummins 300hp, 8.3. Build number 4864. Vin number 1F97D536XTNO54271. Purchased October 31, 2019.

Re: Changed out my 2 solenoids under the battery isolator, no start

Reply #9 –
HD is not the correct term.

Constant duty is what you are looking for IF the solenoid (another name for big relay) is for more than momentary use.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020
 

Re: Changed out my 2 solenoids under the battery isolator, no start

Reply #10 –
Ok. Ronnie at FT tech verified all my wiring  and then checked and called me back and yes, the solenoids do need ground wires as you said. Purrs like a kitty again. These are continuous, constant duty solenoids. I called Intellatech direct. They are not submersible but will be ok where they are mounted. Couldn't sleep much last night I was so perplexed by what I could have done wrong. Talked to the LORD a bunch!
As always, thanks for the help!
1996 U295-36, Cummins 300hp, 8.3. Build number 4864. Vin number 1F97D536XTNO54271. Purchased October 31, 2019.