First of all, Happy Thanksgiving to everyone. Leaving a family dinner. Last night we were in the motorhome and I noticed my running lights were not on. I had this problem when I first bought the coach in 2020 and replaced the headlight switch and that fixed the problem. I can't imagine the switch has already gone bad in 4 years?? Grateful for any suggestions on where to look or where to start. TIa.
Mike
The AUX lights are powered through a relay. This relay is under the lift-up dash, in front of driver seat, over toward the left side. You should see 6 or 7 Bosch type relays grouped together. Relay number 54 is for the AUX lights. If you have the B-2037 12V wiring diagram in your owner's manuals, look around the top left corner of the diagram for the relay location. Try replacing old one with new relay and see what happens.
Thank you Chuck, I tested the relay with my meter, it does appear to be bad, should I stick with a Bosch relay, stores around me have other brands, said they'd have to order the Bosch.
Bosch brand name costs extra plus hard to find, and I don't know if they are actually any better in the long run.
I usually buy whatever generic brand I can find, and carry a few spares in my parts drawer just in case. 8)
I use these .
Rated 40 amp.
Autozone probably.
If the relay is a Bosch 0-332-209-161 and you want to stay with the OEM specs, then you need to get a relay with a resistor. The resistor is internal to the relay and goes between pins 85/86 (the coil) to stop/reduce electrical spikes traveling back to the control circuit. Ones with a diode serve the same purpose.

This is what you will see when you look at the relay body, the resistor is the empty rectangle.
Possible replacements are:
- GEBE 993071
- Hella 87420 (now 933332181)
- NAPA AR143
- Echlin AR143
- Tyco V23234-A1001-X043
I've used the GEBE one, it has a slightly higher amp switching capacity BUT the mounting tab is on the opposite side from the Bosch, so you need to have the cable slack to turn it 180 should you be using the mounting screw. I have no experience with the others.
Do you need the resistor or diode ... I don't know, you would have to check with FT. It may have been required in some places and to keep it easy, they used it everywhere. So DWMYH.
No need for a resistor or diode on that circuit. It's just being controlled by a switch. On newer equipment where the relay is being controlled by an electronic controller, the resistor or diode would be needed to protect the controller.
I replaced the relay, still no running lights, I'm open to new ideas and suggestions.
Which lights are not working? The aux lights that are turned on by the switch on the side panel are running off the relay, they also need the key on to work. They are the lights down at the bottom of the front end. The parking lights that come on at the first notch of the headlight switch are not on a relay.
It's the lights over the windshield and the lights at the top at the rear of the coach and there's a few lights up high on both sides of the coach. The auxillary light above the front wheels are working. I call the high lights the running lights.
ah. the clearance lights. There is a 10amp fuse for those, and relay #52. Check those.
So we've been talking about the wrong lights for this whole thread...
My bad...I made erroneous ASSumption in the very first reply.
Good job clearing that up! :thumbsup:
#52 relay for the win, bingo, you guys are the bee knees! Thanks so much. I will try to do better with terminology!!
No problem with the terminology. Everyone calls somethings different names. Glad we got it working for you.