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2003 Neptune propane indicator lamp / solenoid issue

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I purchased this lamp in an attempt to fix the "no indicator light" problem".  My solenoid was working but no light.  I removed old lamp and replaced with this and still no light. Solenoid worked. In an attempt to get light to work, I reversed wires and still no light but... now solenoid will not activate.  No sound from solenoid and, of course, no gas in coach. I tried jumping wires to lamp together in an attempt to bypass but nothing.  Could I have blown a fuse re. solenoid?  Searched manuals but cannot find where this fuse may be.  Any ideas. 

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10 hours ago, Marine Boy said:

Looks like the light you bought is a high voltage ac light and I would believe that the solenoid is 12vdc, so indicator light you bought wouldn't work.

You are correct... I bought the wrong light.  Oops.
Could you comment as to why the tank switch no longer opens / closes the tank solenoid?
Any suggestions re. solution. We have a trip planned this weekend and it's getting cold in Ohio!

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  • Tom Cherry changed the title to 2003 Neptune propane indicator lamp / solenoid issue
  • Solution

Start with the basics.  Pulled your manual.  Do you have ANY electrical prints in the back....they are NEVER in the online manual.  If SO....you need to find the LP circuit...

If you are NOT familiar with circuitry....then this is a narrative.  The Switch has to have INCOMING power.  One side of the switch has a "fused" 12 VDC line and the other side is the output.  Turn the switch ON....you have power.  Since you have an indicator light next to it, that light is in PARALLEL with the switch.  SO, when you turn ON the switch....power goes to the LIGHT as well as to the Solenoid.  BTW, if you have the Electric Genny Shut off solenoid....an option shown in your manual, then BOTH solenoids will get power.

It is not clear WHAT you did when you "Reversed" the wires.  I would NOT have suspected that would have blown a fuse....but it did....WHY....??  BUT, i can tell you that when you connected or bypassed, you sent positive power to GROUND.  FUSE BLEW.  That is the Quandary.  Without having someone with electrical knowledge and a VOM, I can't do more more.  BUT, for your information....and in the future.

On the switch, there will be a wire that brings power IN.  There will be a wire(s) that goes to the LIGHT as well as the ONE line or side of the solenoid(s).  There are TWO LINES going to the solenoid....POSITIVE and NEGATIVE.  It probably DOES NOT matter which side of the Solenoid Coil. Those same lines are connected to the indicator lamp.  Switch ON....you light the light and power the solenoid.  Find the INCOMING line to the switch.  If you can test power then do it.  Otherwise, you may be in over your head.

You need some electrical skills and some circuitry knowledge to go from here.  Basically, you shorted out a POSITIVE line to GROUND....can't way WHY that happened when you reversed... BUT definitely shorted it out when you CONNECTED them or tried to bypass the light.  POWER is gone to the switch.  You have TWO issues.

First....you need to restore the power....find the fuse.....or have someone do that.  IF the fuse is so elusive....as in there are NOT any prints in the back of your manual, then a new line, fused with a 3 - 5 Amp inline fuse will be needed.  

THEN...A new 12 VDC indicator light....it does NOT have to be an incandescent it can be neon or LED.  Here is a link to one  Your SEARCH would be PUSH IN 12 VDC indicator or maybe "Pilot" light.  This one screws in....I do NOT know HOW the switch panel is made and how to get to the back of it.  BUT, any common 12 VDC pilot light will work...


If I understand the schematic in the manual.  You have PRIMARY shut off valve....but it has a Solenoid on it.  So, the ONLY way to get Propane into the MH (and maybe to the Genny if you have the OPTIONAL one) is to power the solenoid....WITH the primary valve(s) opened.  The circuit or a new one has to provide POWER to the Solenoid....

FWIW....This is an "UNUSAL" system.....and it is NOT used, to the best of my knowledge on later models.  I have a simple tank with a shut off valve that goes into the regulator....and that is is.  It might be costly to have the tank replumbed to eliminate the solenoids.....I ASSUME that the solenoids are replaceable....but this is just an assumption.

Therefore, you are going to have to fix the control circuit. NOW...if that is beyond your skill set....then find a tech.  That Tech should understand BOTH the Electrical and the Propane systems.  

Quite SIMPLY.....if you cannot get to the back or the "inside" of the switch area....then you can ADD a manual switch on a bracket beside it.  All it needs is an INCOMING (Fused of course) power and a switch and an indicator lamp.  The circuit is NOT that complex....but how or what Monaco used is the issue.  MAYBE an LP supplier that does service work can do that or an RV tech.

Wish I could help more, but if you do not understand how the circuit works, then I am reluctant to tell you HOW to fix it....but from a Narrative point of VIEW....I can offer the above.

ONE FINAL COMMENT.  IF you locate the incoming wire and the FUSE.....removed the light.....tape OFF the ends of the leads....that way, the switch will NOT go to ground.  Then use it until you can get a competent tech to replace the indicator lamp....with an appropriate 12 VDC one.  

Good Luck.  OTHER Neptune or similar MH with the Solenoid on the main shutoff might chime in here....



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Thank you for the in-depth reply / explanation and for the time spent composing it.
VERY helpful... I understand what is involved in diagnosing and solving my problem.

Regards, John

I finally found the blown fuse shunting power to the LP solenoid.
It is fuse #6 in the front distribution panel, located roadside forward of front wheel. Labeled "Service Lights"
I hope this helps saves someone the time it took me to find it (after testing fuses in 3 different boxes).

Regards, John

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