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Towing wiring question

Yahoo Message Number: 79893
I've had trouble getting the wiring working correctly for my tow vehicle. After a lot of diagnostic work last night, I figured out it might be a problem with the coach and not the tow vehicle. The voltage on the brake lights seems too low. I measured the voltage at the 4 round plug on the back of the coach. The tail lights measure around 11.6v, but the brake lights only measure 8.8v. I took off the cover and bulb on one of the tail lights and measured the brake voltage there wondering of maybe my tail light converter was bad. It measured only 9.2v. Does this seem too low? The brake lights on the coach don't seem that bright. Just for comparison, I did the same measurement on my truck and it was over 11v.

Jim 99' Magna #5629

Re: Towing wiring question

Reply #1 –
Yahoo Message Number: 79894
First check and clean grounds for the brake lights. Then check the voltage coming in and out of the brake light switch. It is air operated and may have dirty contacts, or more accurate, pitted contact points in the switch creating resistance. If you have good voltage in and out of the stop light switch and good ground wire at the back, then you have voltage drop some where in the wire harness, most likely at a harness connector. Might want to consider running a dedicated wire from the front to the back to give good clean voltage at the rear. Should be able to find plenty of unused wires to choose from. Do a voltage drop check on them from front to back as well.

Have had a similar issue with my trailer brake wire from my brake control up front to the back, I was loosing almost a volt. Found and added a second dedicated wire from the front to the back and pickup up the lost voltage.

Leonard

97' Magna 5418

Re: Towing wiring question

Reply #2 –
Yahoo Message Number: 79939
Check all your termination points of your circuit. Especially those exposed to the outside elements. Corrosion and loose connections and bad grounds are the main culprit of voltage loss. Too small a gage of wire will also cause voltage drop, but I have not seen that problem with a Country Coach.
For reference...some Country Coaches have a tow board mounted in the bedroom in behind one of the drawers in the night stands. There are jumpers for changing the configuration of bargeman connector that is at your hitch. The configuration should be in your manuals if you have such a board. Disregard is you do not have the tow board.

Jim Hughes

2000 Allure #30511
 

Re: Towing wiring question

Reply #3 –
Yahoo Message Number: 79982
Jim, I had a like problem in that I was getting no voltage at all to the lights in the Towd. In my '01 Intrigue, the TOW BOARD, a 2" x 3" printed circuit board with about 10 resistors, 3 very small relay boxes, five 7.5 amp auto fuses, a transistor, a very smaller plug in board, 2 switching transistors and four plug connectors, was located in the engine compartment on the pax side with a caveat printed on it saying HIGH VOLTAGE. My tech showed me how three small rocks had gotten into the bottom of the open box and shorted it out. He swears that there was absolutely no rhyme or reason for so esoteric an electronic control device to be utilized in this function, and replaced it with a generic $8 3 element 15 amp diode from NAPA. No more problems with getting voltage to the Towd.

Good Luck

Ron & Molly Bodeen, '01 Intrigue # 11262, SWCC San Diego, CA 619 994 0061