Community Forums

rescue5 · 11-19-2013, 06:41 PM

I have a 2006 Thor Mandalay 40F on a Freightliner chassis. The problem is that the right brake lights are not working, but the center brake light and the left side brake lights are working as well. Both sides of the turn signals work and the running lights work on both sides as well. Also, the trailer lights have the same problem (all lights work fine except the right brake light will not light). I have read posts on the internet about a diode under the steering column that may go bad and cause the problem, but I am wondering if this could be the problem that I am having since only the right side is not working. Also, I have tried the typical "quick fixes" like checking the bulbs and unplugging and plugging the harness from the brake light to insure a good connection. HELP??????

koda59 · 11-19-2013, 11:39 PM

I have found at times just looking at the bulbs they will look fine. Have you checked to see if you have 12 volts at the plug? Either that or replace the bulb and go from there.

luvlabs · 11-20-2013, 06:40 AM

The brake light circuits should be on a fuse. Not sure where it would be on your chassis but in general, they would be with other chassis related fuses - often located near the chassis batteries.

Iwillbeit · 11-20-2013, 07:05 AM

I would not lose any sleep of trying to find where the wire is broken leading to the right brake light and that's what the problem should be since the trailer lights plug is also not working on that brake light. I would do just what the repair shop would do.. Run a new wire over to a brake light that's working. I would try to patch in on the wiring harness just before where the trailer lights tee of the harness I'm assuming you have separate turn signal lights that don't use the same brake lights of course. If not, it's a little more complicated but still doable.

Randy

rescue5 · 12-26-2013, 04:42 PM

I have checked the fuses and bulbs. They are fine.
I do not have separate brake lights and turn signals. The same bulbs are used for both (like a trailer). The voltage for the wire for the left brake light is only reading 6.5-7 volts which is not enough to light up three brake light bulbs). The left side is showing 13.5 volts ( while hooked up to shore power and charging).
After a hour and a half phone call to freightliner, the technician said there was a "optional circuit" which combines brake lights and turn signals for combination style lights. This is a separate circuit from the trailer light circuits that lead to the trailer connector. The technician be,inches that it may be a faulty turn signal switch, but I'm reluctant to believe that since the turn signals work just fine. Especially since the coach only has about 23Kmi on it. Still scratching my head on this one. Anyone have any thoughts (besides requiring the left side brake lights to the right side). Is like to fix this properly if possible. Thanks.

Hooligan · 12-26-2013, 08:09 PM

Any chance rodents could have got to the wires? This is what my wires looked like thanks to squirrels... All my lights worked, brakes and turn signals together -when using either one..

BFlinn181 · 12-26-2013, 08:43 PM

When you said you only measured 6.5~7 v, was this against a chassis ground or the light socket ground? It could be a bad ground connection.

rescue5 · 12-26-2013, 11:59 PM

The rodents are a possibility, but I've been under the motorhome tracing the wiring looms and I haven't seen any indications of the critters.

As far as measuring the voltage. I measured the voltage to the frame ground. I'm assuming that the ground to the lights are good, since the turn signal is working fine and since it is lighting up the same light bulbs for the brake light and turn signal, it is probably using a common ground.

stink · 12-27-2013, 01:38 AM

The turn signals work on the right side and you stated that the turn and brake lamps use the same bulb. With wiring using the same bulb your brake lamp power goes thru the turn switch. I would listen to the fl tech as I also agree. Try this, have somebody watch the right turn bulb, start engine, turn on right turn signal, step on brake, using cell phones or radios ask your watcher if the right turn signal stopped flashing when you step on brakes. If they still flash then the turn signal switch is defective. If the bulb goes out try wiggling the emergency flasher switch. If the brake lamp or turn light so much as flickers, replace turn switch.
If your emergency flasher switch is on the top of the coluum even in hieght with the turn lever you might have the same switch as mine. The switch can be had at most parts stores, just ask for one from a 1989 ford mustang. Yup it will fit!!!

**Petro** · 12-27-2013, 08:07 AM

I had a similar problem. My RR signal would not work sometimes. It gradually got worse and I found that if I raised the lever by hand the RR signal light would work. After a call to the Freightliner help line I was told to replace the signal light switch and they gave me the part number. After replacing the switch my problem was fixed. Good Luck;

Don

rescue5 · 12-27-2013, 10:22 AM

Stink,
I didn't have anyone to help me watch the signals, so I had to do it myself. I put the right signal on, and then applied the brakes. The right turn signal was still flashing brightly like it is supposed to be. I then did the same test on the left side and it works the same way (except the brake light works on the left side when not flashing for a turn signal).
I'm not sure how that test would point to the turn signal switch. Can you explain a little. It seems to me like that is the way the lights are supposed to function. When the brake lights are on, if you activate a turn signal, the same "brake light" will flash on and off for the signal while the opposite side should remain a constant bright illumination for the brake.
If the switch is bad and causing a resistance to drop the voltage, is there a way to check the voltage prior to the switch, and after the switch? I'm not opposed to replacing the switch, but the $150 price tag on it makes me want to make sure before I buy one.
Thanks to all for the wonderful advice......hopefully I can get this thing fixed today or tomorrow as my parents will be going on a trip next week.

stink · 12-27-2013, 10:33 AM

The turn switch contacts for the brake lights are worn. This does not allow the constant 12v from brake switch to reach the rear bulb. I have seen this very problem working on busses and when I worked for ford.

rescue5 · 12-27-2013, 10:41 AM

Ok, I'll take a run to freightliner. They have one left in stock.
Thanks again for all the help!!!!

rescue5 · 12-27-2013, 11:25 AM

Just took the bezel off the steering column to get at the switch. Thought I'd try a little wiggling and jiggling of the switch and wires. Low and behold, I now have a left side brake light!!!!!! I'm thinking that the wiring harness connector (black 2"x3" square) that connects to the underside of the turn signal switch was dirty/loose. That would explain the low voltage on the right brake light since a dirty connector could cause a high resistance and a resulting voltage drop. I removed and replaced the connector a few times to clean the connections. I'll drive it for a while and see if it stays fixed. If not, I'll try a new turn signal switch.
Thanks again to everyone for the help. Special thanks to "stinky" as you forced my hand into digging into the steering column!
Just told my folks that it was fixed and they're jumping for joy!