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Pull · 09-09-2018, 05:48 PM

Quote:

Originally Posted by Skip426

Ok , I think I have a fair understanding of what you've done so far .
Correct me if any of these statements is wrong.

The problem ; blown fuse ;
1; doesn't happen with the wiring to the front end disconnected at the connector in your first picture , but nothing works ?
2 . You've tested the headlights and marker lights separately ( but didn't elaborate on method ) and neither set of lights blows a fuse.
3. When the connector is hooked up and the lights are turned on to marker light , the fuse holds , but as soon as the headlights are turned on the fuse blows . If this is correct , then the wiring to the headlights ( which includes the butt connector in the second picture) is suspect to be the cause of the short.
Right now I'm thinking the side markers are a separate problem. Particularly if the fuse doesn't blow when the rest of the marker lights are on.

Questions . So far you've mentioned marker lights and headlights , are the coach's tail lights also part of this problem too ? Or are they on a separate fuse?
You tested the side marker lights for power ; did you check the ground circuit from the sockets to the frame of the RV. for zero ohms resistance?

Hi Skip, this is helpful but a few corrections:

#1 the marker lights do work in this scenario (with the exception of the 2 side marker lights that do not seem to be connected. By marker lights I’m talking front and rear clearance lights and tail lights). The connector unplugs the headlights and front marker lights next to the headlights.

#2 the test I did for the marker lights was to disconnect the connector mentioned in #1 and they come on. For the headlights I would connect the connector in #1 and pull the marker fuse and the headlights work. Something to note here is that there is a 25A headlight fuse in an adjacent fuse box that when pulled will not allow the headlights or marker lights to operate. Furthermore, when I trace the connector from #1 back to the fuse box and and disconnect the fuse box end of the harness, I don’t blow fuses that way either. I think I will check the butt connector next as I think you may have nailed the problem.

#3 the marker fuse blows whether I pull the headlight switch to the marker position or headlight position.

The tail lights are also part of the equation - it looks like the brake lights are on a separate fuse. I’ll test the side markers for resistance on the ground circuit - it’s looking to me like these may not even be connected but it goes into a rats nest of a wiring harness in a tight spot that is going to take some work to get to. I’d like to get the rest of the marker lights and the headlights working first before tackling these two lights.

Thanks for all of the sound advice, I’ll report back the findings of the butt connector.

Skip426 · 09-09-2018, 05:53 PM

I'll wish you " Luck " because when it come to chasing a problem like this I'd rather be , Lucky , than good.

RamiDav · 09-09-2018, 06:50 PM

Reversed polarity somehow when the headlights pulled ???

l1v3fr33ord1 · 09-09-2018, 07:05 PM

Quote:

Originally Posted by Pull

Thanks for getting back to me. Neither of the side markers are on the slide.
The add on 4 pair wire runs under the dash to the back of the coach but seems to be on a separate circuit. I’ve disconnected it and the fuse still blows.
You have a good eye - the second terminal is not in use. A,c,d,e,f are in use. C is the blue wire for the low beam headlight wires and has a butt connector for each of the blue wires from both headlights to the one terminal on this connector. Do you think that is factory? I’ve attached a picture of the butt connector (it’s a little hard to see - someone previously used black spray paint under the hood).

The condition of that connector, including the "paint" is consistent with what I have on my coach, which was built by Monaco on a different chassis. I'd say it's factory.

I have a wiring diagram from a 2004 Neptune that shows the 12V chassis circuits. It includes a headlight connector with pinouts like yours. See page 49 of the attached, Zone C-8.

Pull · 09-09-2018, 09:28 PM

Quote:

Originally Posted by l1v3fr33ord1

The condition of that connector, including the "paint" is consistent with what I have on my coach, which was built by Monaco on a different chassis. I'd say it's factory.

I have a wiring diagram from a 2004 Neptune that shows the 12V chassis circuits. It includes a headlight connector with pinouts like yours. See page 49 of the attached, Zone C-8.

Thanks for the schematic - that looks just like it. Is this for a road master chassis?

I took apart the butt connector and it looked just fine - the problem persists. I ran out of daylight to continue troubleshooting but will pick it up again tomorrow (was hoping to hit the road but no lights = no fun). Thanks everyone for your thoughts/ideas on this.

l1v3fr33ord1 · 09-10-2018, 11:32 AM

Pull-

I could not find a brochure for the 2004 Neptune. The 2005 Neptune is listed as built on a Roadmaster R4R chassis.

It turns out that page 50 of the original schematic is for a model year 2002 HR Ambassador/Monaco Knight. I took that page and marked it up to show the headlight and marker circuits.

This is as close as I can get to a chassis diagram for your coach. Some of the wiring harnesses, connectors, fuses, etc., are similar between years and models, even including your 2000 DP and our 2008 gasser. That means we can dig a little deeper with some cautious confidence. In the meantime, look over this diagram.

RamiDav · 09-10-2018, 05:18 PM

There is a way you may be able to work around the problem

This work around will probably be an improvement anyway .

Many RVs are plagued with weak headlights due to low voltage to the
headlights ( HL )

This is usually because of long undersized wires .
Normally the remedy is to install relays

Relays take the load of the headlights away from the HL switch and wires
since they will then only be operating the relays , the relays will in turn
operate the HL .

Rather than trying to explain it I am including a link that will show how
it's done .

Daniel Stern Lighting Consultancy and Supply

Pull · 09-10-2018, 06:27 PM

Quote:

Originally Posted by l1v3fr33ord1

Pull-

I could not find a brochure for the 2004 Neptune. The 2005 Neptune is listed as built on a Roadmaster R4R chassis.

It turns out that page 50 of the original schematic is for a model year 2002 HR Ambassador/Monaco Knight. I took that page and marked it up to show the headlight and marker circuits.

This is as close as I can get to a chassis diagram for your coach. Some of the wiring harnesses, connectors, fuses, etc., are similar between years and models, even including your 2000 DP and our 2008 gasser. That means we can dig a little deeper with some cautious confidence. In the meantime, look over this diagram.

Thank you for the diagram!

While combing through wires under the dash I heard a wire make contact with metal or another wire. I’m no longer losing the marker fuse but I cannot get the marker lights to work now... the headlights are fine.

Question for folks here - if your marker fuse is good and you no longer have marker lights, where would you look?

Pull · 09-10-2018, 06:29 PM

Quote:

Originally Posted by RamiDav

There is a way you may be able to work around the problem

This work around will probably be an improvement anyway .

Many RVs are plagued with weak headlights due to low voltage to the
headlights ( HL )

This is usually because of long undersized wires .
Normally the remedy is to install relays

Relays take the load of the headlights away from the HL switch and wires
since they will then only be operating the relays , the relays will in turn
operate the HL .

Rather than trying to explain it I am including a link that will show how
it's done .

Daniel Stern Lighting Consultancy and Supply

Thanks for the information. I’ll noodle over this some more.

Pull · 09-12-2018, 05:24 PM

Well folks, after working on this for some time I think I have a bad distribution panel board. The 7.5 amp fuse for the marker lights on this board does not get power.

I guess I’ll pull it out and see if it can be repaired and if not it looks to be $900 for a refurb (looks like they are hard to come by new). Anybody have any other suggestions or is this the only option I have?

Skip426 · 09-13-2018, 12:05 AM

OUCH !!!

Could you post a picture of the board in question , maybe someone will have a source or a fix for what's happened.

l1v3fr33ord1 · 09-13-2018, 05:00 AM

Pull-

A failure of the FDP circuit board is possible, but unlikely.

At this point, it would probably help if I spoke with you by phone. I'll send you a private message with my contact information.