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Topic: Bad Boost solenoid? (Read 1030 times) previous topic - next topic

Bad Boost solenoid?

I disconnected the pos battery cable that goes to the BOOST solenoid.
Reason? All the 12V components in the coach would still be functional even if the "Salesman's Switch" was in the OFF position.
Disconnect the Boost engine cable and all 12V features on the coach side went off.
Bad Solenoid? How do I determine replacement? Part #?

I HATE ELECTRICAL GREMLINS!!!!!

Re: Bad Boost solenoid?

Reply #1 –
Quote from: nitehawk –
1.  I disconnected the pos battery cable that goes to the BOOST solenoid.  Reason? All the 12V components in the coach would still be functional even if the "Salesman's Switch" was in the OFF position.

2.  Disconnect the Boost engine cable and all 12V features on the coach side went off.  Bad Solenoid?
1.  UMmmm...you're gonna have to explain your reasoning on your first statement.  Which "pos battery cable" did you disconnect.  There are two pos battery cables connected to the BOOST solenoid - one from each battery bank.

On my coach, power from the COACH battery bank goes through the Salesman Switch and then back to the main 12 volt circuit breaker panel.  That power circuit does not go through the BOOST solenoid.  Turning the Salesman Switch off would cut power to the components on that circuit, regardless of what is or is not connected to the BOOST solenoid.

2.  Easy to test for a bad BOOST solenoid.
Remove one of the big battery cables from the solenoid - doesn't matter which one.  With the BOOST switch in the OFF position, the small post (or posts if there are two) should not show any voltage.  Check voltage on both of the big posts on the solenoid.  Post with cable attached should show battery bank voltage.  Post with no cable attached should show zero volts.  (If both big posts show battery bank voltage, the solenoid is stuck in the closed position - it is bad).

Now turn the BOOST switch to ON position.  The small post (or one of the small posts if there are two) should show 12 volts.  Check voltage on the big solenoid post with no cable.  It should now show the same (battery bank) voltage as the other big post.  If it does, solenoid is good.  If not, solenoid is bad.

Re: Bad Boost solenoid?

Reply #2 –
All 12 Volt lites, etc. were still on even with the switch in the off position? In that case, in the bay just forward of the entry step, there is a solenoid. It is connected to the salesman switch. I would think that this could be the issue....
and not the boost solenoid as Mr Chuck suggested....

Re: Bad Boost solenoid?

Reply #3 –
Thanks, I will go check after my shower.

Re: Bad Boost solenoid?

Reply #4 –
The red cable I disconnected was the one from the engine battery to a solenoid mounted on the frame.
Just went out and checked. In the forward compartment, on the ceiling, is the Salesman's switch and ONLY the salesman's switch. There are three heavy gage red cables going from the switch to the compartment under the steps where the batteries are located.
One of the red cables is from the POS side of the coach battery to the salesman's switch.
Another of the red cables goes to the forward side of the solenoid fastened to the coach chassis frame.
The other red cable disappears under the chassis frame.
On the solenoid left side is the red POS cable I took off the POS side terminal of the engine battery.
Also, there is a small gage red wire under the large cable end on this solenoid post.
On the right/forward side of this solenoid are three red cables. One comes from the salesman's switch. The other two heavy gage red cables come out from under the chassis frame.
MIdpoint on the solenoid, pointing right at me, is a small diameter post with a small gage blue wire attached.
That is it, except for a strange two post electrical unit on the forward wall of the battery compartment.

Re: Bad Boost solenoid?

Reply #5 –
'89 and '93 are not the same most likely. There is an easy way to test the boost solenoid. Plug in, put a volt meter on the cigarette lighter plug and switch the boost on. If the solenoid is good, the voltage will go up.

Re: Bad Boost solenoid?

Reply #6 –
Got that cig voltage meter. Can do. Thanks.
Lets me give my back a rest for a few days.

Re: Bad Boost solenoid?

Reply #7 –
Quote from: nitehawk –
Got that cig voltage meter. Can do. Thanks.
Lets me give my back a rest for a few days.
This is assuming all is original. From the factory, ONLY the cig plug is wired through the start battery. Hopefully previous owners kept it this way. That's another thing you may have to check. Since everything is on when the sales switch is off, could be all batteries are tied together.

Re: Bad Boost solenoid?

Reply #8 –
Norm,

Your 12 wiring must be somewhat different from my '93 model.

My Salesman Switch has 3 medium (2 gauge red) battery cables attached.  One cable comes into the switch from the coach battery bank.  One cable leaves the switch and goes back to the main 12 volt circuit breaker panel in the center main storage bay.  The third cable goes from the "always hot" side of the switch over to the generator starter.  This sounds similar to your switch.

My BOOST solenoid only has two cables attached to each of the large posts.  One cable comes in to each post from the battery banks, and one cable goes out to the battery isolator.  I'm trying to figure out what all the other wires might be on your BOOST solenoid mounted on the frame.  You really need to see the 12 volt automotive wiring diagram for your ORED model.  The Forum library has a diagram for the URED chassis model.  You might compare it to what you are finding by looking at the cable ID tags, and see if it matches your coach's configuration.  See below:

https://www.foreforums.com/index.php?action=media;sa=media;in=3831

Without the proper wiring diagram, or being able to physically trace all the wires connected to your solenoid, it will be hard to figure out what is going on with your "situation".  Hopefully, another Forum has the correct diagram and can upload it to the Forum library.

Re: Bad Boost solenoid?

Reply #9 –
Norm, am looking at my coach and the wiring diagram. The solenoid you are referring to IS the boost solenoid. On the "salesman switch" side of the solenoid you are referring to, the three 2 ga. red wires go to the gen set starter solenoid, the isolator, and of course the salesman switch. The small blue wire comes from the Boost Switch on the dash. On the opposite side of the boost solenoid, the 2 ga red wire runs to the Chassis battery.When you get the chance, check the little blue wire on the little Center post and see if it is hot. If so, the boost switch on the dash may be damaged internally keeping the solenoid hot all the time, and the batteries tied together all the time. ALSO, at the boost SWITCH in the dash are 2 wires plugged into said switch. they both have directional diodes in them to prevent this same thing from happening from a backfeed. (I really believe the diodes are built into the boost switch). Anyway, if that little blue wire at the solenoid is "hot" all the time, there is the problem. (Be sure you have the chassis battery positive connected at the battery, or you won't have any juice to the ignition side of the ignition solenoid which is under the dash lid right ahead of the driver. It has to have juice to feed the boost SWITCH). If you need to, give me a jingle and I will help you walk thru it.  Also, I THINK the mystery device is an 80 amp circuit breaker to the charger.
 

Re: Bad Boost solenoid?

Reply #10 –
See ORED wiring attachments:
The RH section, LH section and the 12 V Auto section show about all there is as to what I posted prior. The rest are for reference.....