Community Forums

bobwalter · 02-04-2012, 02:55 PM

This whole thing started because of a rapid flashing of my right turn signal. I have a 1993 Rexhall Class C on a Ford E350 chassis. I took the tail light lenses off to check the bulbs. Found that the right hand bulb was flashing the lower intensity filament instead of the high intensity one. Switched the bulb out with a known good one and had the same effect. Checked the bulb sockets and found considerable corrosion in the sockets and on the bulbs. Cleaned the sockets thouroughly with wire wheel on Dremmel tool. Problem solved. My multimeter was out so I decided to test the voltage at the socket. This is where my problems started. The tail light circuit has 12 volts to it but the turn signal circuit has only 6 volts. The lights flash and light but I think they could be brighter. I have LED tail lights on my toad and the 6 volts is not enough to light all 18 of the LEDs. Only 2 light. They work but there are a lot more lights that could be working. When I provide 12 volts direct to the toad circuits with a battery charger, they all light and all is good. I only have 6 volts to the coach signals whether the toad is connected or not. I have not checked the brake light voltage because I am working alone. I have installed new ground wires directly to the frame for all the circuits and ground the area clean before install.

This is driving me crazy. Anybody have any ideas. I am afraid that it might be in the turn signal switch. If so, I am not sure I want to tackle that kind of repair myself. Any help would be appreciated.

Bob

gfs1943 · 02-04-2012, 03:11 PM

I believe you have a broken or disconnected ground wire, so the ungrounded bulb is seeking a ground and backfeeding through another bulb filament.

HeapBigEngin · 02-05-2012, 12:38 AM

It does sound like grounding issues.

Wondering, however, if you have the original turn signal flasher in your unit. Sometimes old flashers can cause resistance and eat up voltage. I would also check for 12 volts coming into and out of both the flasher and the fuse box for these affected circuits. Remember, anytime you have a wire splice or plug-in along a circuit, you can develop voltage drop as much as 1-2 volts at each point....mainly due to a poor or corroded connection. 3 of these that are having corrosion or continuity issues can easily add up to a 6 volt loss at the bulb. If you are sure you have cleaned up the corrosion and potential grounding issues and if the flasher and fuse box check out OK, I would then start looking for voltage drop from there back to the sockets. I see you are in Florida....could that be contributing to any corrosion?

Good luck. And PLEASE let us all know how this turns out....thanks!

bobwalter · 02-05-2012, 07:02 AM

Thanks both for your reply. I too think it is a grounding issue. I went under the instrument panel to attempt to measure voltage coming from the steering column but that is impossible. The wiring under there looks like a million wires just dumped into a box, mixed up and shoved under the dash. Thanks for the tip on measuring at the flasher and the fuse box. I hadn't thought of checking there (DUH). Sometimes the brain just eases into neutral. I will get back to it today and post results.

Thanks again,

Bob

subford · 02-05-2012, 08:35 AM

First off I would say you do not have a grounding issue now. Sounds like you had one to start with at the lamp sockets though.
That would have the opposite effect, the voltage would stay high (~12VDC).
Sounds more like bad connections. So check all the voltages all along the wire plugs from the front to the rear as HeapBigEngine said above.
You may also want to install relays for the toad to take the load off the wiring circuits of the RV.
Pusherman "Don Pophal" talked about this in the link below:
http://www.irv2.com/forums/f23/quest...ml#post1075189

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HeapBigEngin · 02-05-2012, 02:28 PM

Bob....I don't envy you in finding the problem. Personally, I have a love/hate relationship with electricity....I love it when it works, and hate it when it doesn't.

Re your wiring, I suggest you first keep it simple and look for the most obvious things. If your turn and brake filament are the same in your system, just wondering what kind of voltage you have at the socket when activating the brakes.

RV's typically have a ton of "bundled" wires and connections running all over the place. This seems especially true in the rear of most RV's because of trailer and brake wiring and other stuff mated with the coach/chassis wiring back there. If your flasher and fuse box voltages check out OK, I would probably start looking back there first for plug-in and splicing issues that could easily cause voltage drops within any circuit that they share. I have had my share of bundled wiring connections (wrapped oftentimes in black electrical tape and housed in the ribbed sheathing) that was so crapped up that I was amazed at how any voltage got in....let alone got out! These types of connections are notorious for trapping condensation and moisture, especially at the rear of most RV's. Operating in humid or rainy climates only adds to the problem. By the way, just MO, but I strongly agree with subford's suggestion re relays. Your coach is powering a ton of lights on that toad, even if they are LED's.

Good luck, and thanks for replying to us. Please let us know....thanks!

bobwalter · 02-06-2012, 09:05 AM

OK, I threw in the towel. I surrender. After checking all connections, chasing and redoing grounds, cleaning light sockets, replacing electronic flasher, I still have 6 volts to the flashers. I checked the voltage at the flasher and I have 12 volts incoming. Outgoing, I have only 6.8 volts. By the time it gets to the rear harness it is barely 6 volts. I am pretty sure it is a ground in the flasher harness under the dash. I would replace the ground but it cannot be done without removing the drivers seat. As it is, I cannot get both hands under the dash at the same time. If I was the size of a three year old, I might fit. Besides the wiring under there is a total nightmare. I am afraid that if I pulled a wire loose I would never find where it goes. I think I would rather leave well enough alone.

I have ordered a Tow Ready 119146 ModuLite Trailer Light Power Module on Amazon Amazon.com: Tow Ready 119146 ModuLite Trailer Light Power Module: Automotive. I think it is the best solution for my problem.

I realize that it is for the trailer/toad plug but I have a question. Can I disconnect the rear flashers on the coach from the original harness (remember they are only getting 6 volts) and connect them to the new power module? That way I will have 12 volts to the flashers on the coach which will give me added brightness and visibility when not towing the toad. I believe that the unit is rated for ten amps per leg. I will be powering it direct from the chassis battery with a 10 gauge line.

What do you think. Should I just run the toad harness from the module or the coach signals too?

Bob

subford · 02-06-2012, 10:08 AM

What would a ground have to do with low voltage along the wiring run?
The only ground that I can think of would be the battery ground to the frame.
If your frame is not grounded that would do it but that ground is coming off the NEG side of the battery.

Ford trucks have a ground lug in the center of the ground cable coming off the NEG side of the battery bolted to the frame but the E-series did not in 1989. They had the center lug bolted to the body and not the frame. I do not have a newer E-series than that to look at but maybe the 1993 did the same and did not have a grounded frame.
The ground wire from most trailer plugs is grounded to the frame. And if your frame is not grounded like most E-series than that may be your problem. Just run a large #10G wire from the NEG post of the engine battery to the frame.

bobwalter · 02-06-2012, 02:46 PM

Bill,
The flasher has three wires to it. One is the incoming 12 volts. The second wire reads 6.8 volts blinking with the flasher. I think the third wire is a ground wire to complete the circuit. If the ground is not good (only partial/ high resistance) that would cause the circuit to only show partial voltage downstream. I think this is correct???? Maybe? Only my guess here.... Does that sound logical??? I am not an electrical whiz but I have done some of it.

What do you think? Am I going in the right direction??? Good thing I don't have much hair or I would be bald by now. I am going to beat this gremlin!!!!!!!!!

Appreciate your thoughts and input.

Bob

mikf · 02-06-2012, 02:57 PM

is it the same bulb for the turn signal as the brake light? if so how much voltage do you have with the brakes applied?

bobwalter · 02-06-2012, 02:58 PM

After re-reading your last post, I finally understand what you are saying about the negative cable. I will check where it is fastened. If it is ti the body, I will put another cable (jumper) to the frame. Corroded body mounts could cause lots of trouble.

Thanks,

Bob

bobwalter · 02-06-2012, 03:01 PM

MIKF,
Yes it is the same bulbs. I have not been able to check the brake circuit because I am working alone right now. My leg isn't quite long enough to do it myself. Will have to fine a neighbor. I am cirious about that reading too.

Thanks,

Bob

mikf · 02-06-2012, 03:11 PM

Bob, put a clamp on a broom handle or something {I use a cane}and adjust the clamp to fit under the steering wheel and hold the brake pedal down. works for me.

bobwalter · 02-06-2012, 03:11 PM

HeapBig...,
Thanks for the comments and suggestions. I am sure also that it is a ground also. I replaced the flasher unit today and still only have 6.8 volts coming out. As stated earlier, I think the third wire coming off the flasher is a ground. That could be the culprit but I have been unable to check it because of not being able to get both arms under the dash. I think that could cause all the problems if the ground was partial. Guess I will go to the circus and hire a contortionist..... I will see if I can bend my body a little more tomorrow and get under there. I did order the relay for wiring the toad.

Appreciate the help

Bob