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Topic: 1998 U295 Boost Solenoid question  (Read 619 times) previous topic - next topic

1998 U295 Boost Solenoid question

1998 U295 Cummins 8.3, Allison 3060R, air throttle - 162,882 miles
Our Allison transmission intermittently will not shift out of first gear and the retarder will also intermittently not activate, request assistance  - starter solenoid / other electrical issue? 
History:
  • 2/2017 - 146,196 miles had shift pad rebuilt (Transmission Instruments, TX) because it failed to go into reverse.
  • 4/2018 - 150,662 miles transmission retarder solenoid replaced, air leak, odo & hour meter flashing and gage needles sporadic, cruise control cuts out.  New solenoid corrected problem.
  • 7/2019 - 154,154 miles on a 1300 mile round trip coach went into limp mode on I-40 east of Knoxville, TN on trip from VA.  This happened a couple of times prior to this, cruise control would also periodically disengage. Clark Power Services, Knoxville was very helpful with diagnosing over the phone, error codes 2216, 6412, 2511,2544 and recommended replacing the output speed sensor.  Replaced sensor, all good.  Coach shifted properly and cruise control did not disengage.
  • 4/2023 - 162,429 miles changed trans fluid and filters (Transynd and Allison filters)
  • 7/8/24 - 162,593 miles coach would not shift out of 1st gear, shift pad read "6" at start up but changed to "1".  After fiddling with shift pad it shifted properly.  Error code 2511
  • 7/15/24 - 162,636 miles starting on a 480 mile round trip the coach would not shift out of 1st but after twice around the neighborhood and a shutdown we were off.  No further issues shifting (but I didn't shutdown until we were at our campsite) but retarder activation was intermittent. Added error code 2112 to 2511.  Transmission oil level reads ok at shift pad. 2112- Throttle sensor failed low, 2511-Output speed sensor, detected @ 0 speed in 1st.
  • 7/17/24 - on return trip I left the Boost switch on the whole trip with no issues.  Coach shifted and retarder activated properly and no new error codes.

I'm not much at electrical troubleshooting but could this be a weak starter solenoid issue?  Everything worked properly when Boost switch was hot.  If so, which solenoid (at batteries, under the bed or is there another?) and what would be the specs?  In the forum I see that Cole Hersee PN 24213 is referenced as the boost solenoid, would this be at the batteries?

Thanks in advance for any assistance.
1998 U295 36' WFTE No Slides, C8.3-325 Cummins, Build #5262
Motorcade #17786
FMCA#1464376

Re: 1998 U295 Boost Solenoid question

Reply #1 –
What condition are the chassis batteries in and what is the voltage on the dash readout when the engine is running (without the boost switch on)?

Wondering if your alternator output is low and/or there's an issue with the chassis batteries and the lower voltage is affecting the transmission ECU.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: 1998 U295 Boost Solenoid question

Reply #2 –
All three new in 2021, and the volt meter reads 14 volts
1998 U295 36' WFTE No Slides, C8.3-325 Cummins, Build #5262
Motorcade #17786
FMCA#1464376

Re: 1998 U295 Boost Solenoid question

Reply #3 –
First I would start by physically removing and cleaning ALL battery terminals and all frame grounds/engine grounds, as well as the connections and voltage at the isolator. Definitely sounds like a voltage/ ground issue. Just because the dash sys 14volts doesn't mean it getting to where it needs to go.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: 1998 U295 Boost Solenoid question

Reply #4 –
Quote from: Tharris48 –
I'm not much at electrical troubleshooting but could this be a weak starter solenoid issue?  Everything worked properly when Boost switch was hot.  If so, which solenoid (at batteries, under the bed or is there another?) and what would be the specs?  In the forum I see that Cole Hersee PN 24213 is referenced as the boost solenoid, would this be at the batteries?
Thanks in advance for any assistance.
Terminology is important when seeking long distance technical assistance.  We want to all be on the same page.

There are four different "solenoids" associated with the DC electrical starting system on most Foretravel coaches.  To whit:

1.  IGNITION Solenoid.  On older Unihome models (GV) located under the lift-up dash cover, in front of driver.  In later Unicoach models, located behind the removable beauty panel in front of passenger seat, down at the bottom of the circuit breaker panel.  In later models, may be a single solenoid, or two solenoids working in tandem.  The IGNITION solenoid is activated when Ignition Key is turned to ON position.  It supplies power to major circuits in the coach.

2.  BOOST Solenoid.  Located at the rear end of most coaches, often on or near the battery isolator panel.  Easily identified by the heavy POS (+) battery cables attached to both large terminals.  Both heavy cables are HOT all the time.  When activated, this solenoid combines the Chassis battery bank and the Coach battery bank into one large battery bank.

3.  AUX START Solenoid.  Usually located near the BOOST solenoid, often on the isolator panel.  This solenoid is activated by turning the Ignition key to the START position.  Its sole purpose is to send power from the CHASSIS batteries to the engine starter solenoid during the start sequence.

4.  STARTER Solenoid.  Mounted directly on the big engine starter motor.  When activated causes the starter motor to rotate and engages the starter pinion gear with the engine flywheel ring gear, hopefully encouraging the engine to start.

On all model coaches, the Cole Hersee 24213 is a recommended solenoid for positions 2, 3 and 4 listed above.  In the case of the IGNITION solenoid, the 24213 works great on older GV models.  On the newer model coaches, for simplicity's sake, use the same solenoid part number as the one being replaced.

EDIT:  Yes, I know, somebody out there is saying "What about the Fuel Shutoff Solenoid?"
OK....it is also part of the starting/running process, but it's an entirely different type solenoid, and kinda off the track of the OP's questions, so that's why I didn't include it in my list.


1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: 1998 U295 Boost Solenoid question

Reply #5 –
Adding to Chuck & Jeannie: Step 3: sends chassis battery (not high amp) to Starter Solenoid. Only amps needed to close starter-mounted solenoid's lower-amp primary windings flow. Step 4: It sends high amp power from the CHASSIS batteries to the engine starter motor main windings. Transmission will act up if low voltage flows to transmission computer. Found places to measure voltage on some coaches is at breaker behind white bay mounted panel and at breaker on large panel in front of co-pilot seat. We have seen these low voltage readings also affect neutral start solenoid mounted on large panel in front of co-pilot seat prevent engine crank with ignition turned to start position. Bypassing neutral start relay eliminated engine start problem, probably caused by too low voltage at tranny computer.

Re: 1998 U295 Boost Solenoid question

Reply #6 –
Great information everyone! Thank you!  I removed and cleaned the 3 coach battery terminals this afternoon, negative terminals looked good.  Although tight, the positive terminals needed some cleaning.  The boost solenoid is as Chuck and Jeanne stated in #2.  The only other solenoid I've found that looked similar to the boost is on the forward inner bulkhead for the bed, above the King Cruise box (3 terminals vice 4 as on the boost solenoid). I had assumed this was the Aux solenoid.

I found nothing in the removable circuit breaker panel in front of the passenger seat that looked similar to the boost solenoid.  I did however find two 1 1/2 x 2 (?) black boxes (Bosch 0 332 002 150) with heavier gauge wires attached identified on Amazon as relays.  Are these the ignition solenoids referred to.

I'll get under "MO" as we call her tomorrow and do some more checking.

We're planning our 1st retirement adventure VA-TX-MT-WI-OH-VA later this summer and would like to address known issues in the driveway or have the parts on hand before we start.

Also, anyone with a recommended parts list would be great.  I already have spares of all the belts, belt tensioners, filters, air governor, front and rear air brake chambers and electric fuel pump (generator).

Thanks again
1998 U295 36' WFTE No Slides, C8.3-325 Cummins, Build #5262
Motorcade #17786
FMCA#1464376

Re: 1998 U295 Boost Solenoid question

Reply #7 –
Quote from: Tharris48 –
The boost solenoid is as Chuck and Jeanne stated in #2.  The only other solenoid I've found that looked similar to the boost is on the forward inner bulkhead for the bed, above the King Cruise box (3 terminals vice 4 as on the boost solenoid). I had assumed this was the Aux solenoid.

I found nothing in the removable circuit breaker panel in front of the passenger seat that looked similar to the boost solenoid.  I did however find two 1 1/2 x 2 (?) black boxes (Bosch 0 332 002 150) with heavier gauge wires attached identified on Amazon as relays.  Are these the ignition solenoids referred to.
The second solenoid you found under the bed, with 3 terminals, sounds like it is indeed the AUX START solenoid.  The solenoids we are discussing can have three or four terminals.  If they have three terminals, then the small post is the activation connection, and the solenoid grounds through the mounting bracket.  If there are four terminals, one small post is for activation, and the other small post is for a ground wire.  The (2) small posts are interchangeable - doesn't matter which is power and which is ground.

Yes - the two black Bosch boxes (relays) do perform the same function as the single IGNITION solenoid on older models.  One large post on each relay should be hot all the time.  When the ignition key is turned to ON position, both relays should close and then both large posts on each relay will be hot with identical voltage reading.

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: 1998 U295 Boost Solenoid question

Reply #8 –
Some C8.3 engines have intake manifold heaters/fuel injectors controlled by a control panel mounted above King Control, centered on the back wall of the engine compartment.  Panel has a 'tall' solenoid to turn on & off the manifold heaters.

Talking about items without a photo could lead to incorrect responses.

Adding to the dual ignition relays response, each relay controls different sets of ignition powered circuit breakers mounted on the big panel.

Re: 1998 U295 Boost Solenoid question

Reply #9 –
An accurate way to measure battery voltage is with meters that have a dedicated cable from meter to battery.  All measures of voltage from wires that have loads tend to read lower.  Some of the worst places to get consistent accuracy voltage is from dash lighter sockets and other dash devices.

Taking time to make dedicated wire runs to two meters near each other will pay off, as knowing battery voltages is one of the most important meters to measure these critical limited resources.

Re: 1998 U295 Boost Solenoid question

Reply #10 –
Quote from: Tharris48 –
1998 U295 Cummins 8.3, Allison 3060R, air throttle - 162,882 miles
Our Allison transmission intermittently will not shift out of first gear and the retarder will also intermittently not activate, request assistance  - starter solenoid / other electrical issue? 

Experienced the same problem, coach wouldn't shift out of first. Turned out to be the retarder sensor mounted inside panel on side of trans.  No prior indications of problems.  Pricey sensor at Cummins.....
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS

Re: 1998 U295 Boost Solenoid question

Reply #11 –
So I believe the issue is the house batteries, all read 12 volts individually, 13 volts each on the coach batteries. New AGMs due in tomorrow, just in time for the rally at Natural Bridge.
1998 U295 36' WFTE No Slides, C8.3-325 Cummins, Build #5262
Motorcade #17786
FMCA#1464376

Re: 1998 U295 Boost Solenoid question

Reply #12 –
Tharris,

In the first pic. it looks like you are using both a VSR (voltage sensing relay) and a isolator. Is that what I see?

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: 1998 U295 Boost Solenoid question

Reply #13 –
Quote from: Tharris48 –
So I believe the issue is the house batteries, all read 12 volts individually, 13 volts each on the coach batteries. New AGMs due in tomorrow, just in time for the rally at Natural Bridge.
Terminology!  It is important.  ;)  Your sentence above is confusing (to me) because you use two names for the same batteries.

The batteries that start the engine are usually referred to as the ENGINE batteries, or CHASSIS batteries, or ENGINE START batteries.

The batteries that power all the household devices in the coach are usually called the COACH batteries or the HOUSE batteries.

I notice in your first photo that you have a BEP DVSR on your coach.  This could have been installed at the factory, or perhaps by a prior owner.  This device is normally used to allow two battery banks to be charged from the same source, while keeping the banks separated when they are being discharged.  You can read the complete description of this device in the link down below.

A DVSR performs the same basic function as a battery isolator.  When I see both devices installed on the same coach, I always wonder WHY?  If you have had past problems keeping one set of batteries properly charged, it would be worthwhile to look at the way the DVSR is connected.  Perhaps it is not connected properly.  You want to be sure your charging system is up to snuff before you hook up your new batteries.

Digital Voltage Sensing Relay (DVSR) 12/24V

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: 1998 U295 Boost Solenoid question

Reply #14 –
Sorry for the confusion, the pictures were in response to Barry & Cindy's comment "Talking about items without a photo...".  Photos without explanation has the same effect, sorry.

The house batteries are not shown, they were installed in 2015 when we purchased the coach and were removed the other day when it was apparent they were bad, they each read 12v and the inverter seemed to be running excessively.

I installed the coach batteries (shown) in 2021 due to hard/not start issues.  Correct, the coach has both the BEP DVSR and battery isolator installed. I don't know how or why they are there.  This is how we purchased it in July 2015 and have had no issues keeping either set of batteries charged.  Nothing electrically, other than the batteries in this photo (coach) has been changed or worked on since we purchased the coach. The transmission retarder solenoid (?) was replaced but that was a different topic.

The second photo shows the second start solenoid (Aux start?) that I referred to in my original post.

At this point I'm thinking that replacing the 3 house batteries ($) will address my issues noted in my original post.  I've also found a Brett Wolfe post on how to check the 200 Amp start solenoid (pictured below the battery isolator) and picked up a spare.

1998 U295 36' WFTE No Slides, C8.3-325 Cummins, Build #5262
Motorcade #17786
FMCA#1464376

Re: 1998 U295 Boost Solenoid question

Reply #15 –
The BEP DVSR was likely installed by the PO (or I believe Foretravel installed these on request) to charge chassis batteries while on shore power. This is similar to the Trik-L-Start many have used for the same purpose.
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B