Tail lights out, instrument panel lights out, flasher not working

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Mosagra

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So I have this trifecta issue with my Ford chassis, 1999 Itasca suncruiser 37G.  Headlights work, taillights do not work. When I turn on the turn signal, both rear lights flashed simultaneously as if I have the emergency flashers on.

I first noticed the dash lights not working, I thought that was just a lightbulb. When you turn the dimmer switch all the way the overhead light comes on as usual. However the lights that illuminate the instrument panel do not come on at all.

It wasn't till it was getting dark when I noticed the taillights were not working, had to pull over for the night.

I checked all fuses, two fuses were bad but replacing them did not fix the problem.

I thought it was the switch, the light switch/taillights switch is right next to the instrument panel dimmer. So I thought I had a bad switch.

But the flashers are not working also, anybody have any ideas how these might be connected?

 
My first thought was fuses, too.

I could be a bad ground - or several bad grounds in the tail lights.  The turn signals flashing together would point to bad ground, I think.
Do the clearance lights work?  Do brake lights work?

On the instrument panel, is it possible the bulbs are burned out?
 
I think a bad ground (or grounds) is very possible.

Yes, the brake lights work. By clearance lights you mean the lights on top in the rear of the RV? They are out also.

I did not mention it but I had an incident with the left rear of the coach about a month ago, a stick flew up and knocked the cover off the left rear end cap. This is about 8 feet long, from the top to the bottom.

The lights all worked fine then. I put it back on, put it all back together, much better than it had ever been, used Lexel sealer, better screws, a few bolts.

Now that I think about it there was a massive downpour on our memorial day trip, it was on the way back that I first noticed the instrument panel lights were out.

But how could that mess up the flasher? I was pushing and pulling wires under the instrument panel, maybe I messed up the flasher myself.

Oh boy, I'm not looking forward to taking that cap back off.
 
Try the easy stuff first.  Pull the light covers and check the ground from the lamp base to the chassis, and from the ground wire to the chassis.  Check bulbs.  Look for a reason to pull the cap.
 
Thanks, very good advice, hopefully will get time to work on it this weekend. Will let you know.
 
I finally got around to looking at the wiring in the back left of the camper where I had the damage. 

The ground wires appear good to me, solidly attached to the light fixtures. Instead of a short easily traceable run to the frame (no frame several feet up the back of the camper) they go into the wire bundles. The bundles go down to a location near the bumper, one main ground there that appears solid.  Again everything appears solid as far as I can tell.

I traced all the wiring from the back of the rv to the front as best I could, bundles of wires with that black corrugated plastic around them. No obvious external damage.

Not sure what to look at next. How hard is it to put the voltmeter on the wires as they come off the switch?

Any help is appreciated.
 
The front turn signals work the way they should.

However the back turn signals, both of them flash whenever you turn on the right or the left turn signal. I have never heard of that before.
 
Try working the 4 way flasher switch in and out a few times.  They're known to become intermittent and both the front and rear turn signals loop through it.
 
You might have already checked but the fuse for the tail lights generally powers the dash lights. This is so if the fuse blows for the tail lights you will know right away as the dash lights would go out at same time. If not checked i would start there. Rule of thumb with electrical is start at the source then move down the line. A wrong bulb or shorted bulb could also be the cause, blowing the tail  light fuse and shorting internally across the contacts in the bulb socket causing the lights to both flash.
 
This problem is still not fixed. I have a trip planned this week and one next week that are in jeopardy.

I took it to a trailer shop. Have been told nobody knows lights like trailer guys, this particular guy is also an electrician. He had the camper for 3 weeks and was unable to diagnose the problem. He thinks there is a short somewhere but says he cannot locate it.

He says at one point all the lights worked properly for about an hour but then went back to no running lights and both turn signals flashing with either directional signal. The brake lights work, the backup lights work, the trailer light plug at the rear of the camper is same as the the camper lights.

I thought it was the headlight switch itself or maybe the flasher, I replaced both of those yesterday morning but there was no change.

The electrician did find a relay on the dash with a blackened prong, it's a Bosch relay, I ordered a replacement, should be here Monday. Not sure what that relay's role is.

I have traced the entire wiring harness, there are no externally obvious problems.  There are numerous grounds coming off the wiring harness, have not found any that are cut or loose.
 
Do you have separate brake and turn signal lights? If so, you probably have a converter to convert to combined lights on a toad or trailer.  If you have one, it will be up under the rear bumper. If you do have one,  try disconnecting all the wires to and see what happens.
 
ChasA said:
Do you have separate brake and turn signal lights? If so, you probably have a converter to convert to combined lights on a toad or trailer.  If you have one, it will be up under the rear bumper. If you do have one,  try disconnecting all the wires to and see what happens.
Click to expand...

No, brake and turn signal lights are both on the regular 1157 bulb, I have never seen such a device on this camper. Thanks for the tip, though
 
I do not think this is the ground. I am getting continuity from the ground area of the bulb socket to the frame. I have checked both lights in the back and three of the bulbs on the side. (This is the kinda stuff I was expecting my "electrician" trailer guy to check, if he did that he never mentioned it to me.)

I think it's lack of power to this circuit. The fuses are all good, have checked them for continuity.

I have not been able to find a diagram for the fuse panel. This is a 1999 Ford F550 Motorhome Strip Frame.  At least not one that looks like below.

If anyone can help me find a manual or diagram of this I would appreciate it.
 

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