BAC Forum
General Boards => Technical Support => Topic started by: Paul Champagne on December 09, 2021, 11:57:24 PM
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Hi Gang
Just noticed that I have no low beam headlights but when I hit the highbeam switch they both come on? Is the low beam on a fuse or relay as I can't find either one?
Coach is a 2006 Thunder
Thanks
Paul
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Paul,
If your coach chassis is based on Mafgnum, it's either the dimmer switch or the low beam relay if the headlight mod has been installed.
Steve
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On my 2002 Marquis the problem was a corroded connector on the headlight switch. I pulled the connector off the headlight switch and pushed it back on and the problem went away.
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Paul,
If the above suggestions haven’t help.
Circuit Board # 8 in the front run box contains the relays and circuit breakers for the hi and low beam headlights (image attached). The labeling on our coach is incorrect, it reads RH BEAM and LH BEAM, it should read HI BEAM and LOW BEAM. I’ve attached an image of the updated PCB 8 label. The circuit breakers are auto reset and may be labeled “SHORTStop”.
First thing that I’d check would be to see if your fog lights cycle with the dimmer switch. With the fog light switch on, the fogs lights should be on when low-beam is selected, off when hi-beam is selected. If they do cycle on and off, then I would turn my attention to the components on PCB 8.
If the fog lights do not cycle on and off with dimmer switch, I would check the following:
- Connections on the Smart Wheel controller, use caution as they are kind of fragile.
- Dimmer switch connector on the steering column. The connector can loosen when tilting or telescoping the steering wheel.
- Use the Smart Wheel Trouble Shooting manual to check out the controller (manual can be found in Coach Assist).
-Scott
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Thanks Scott I will check this next week to see what is happening and will update my post
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The headlight operation on your coach is much more complex than that of earlier years, there are a number of components involved, PCB 8, dimmer switch, VIP Smart Wheel controller and don’t forget the daytime running lights (DRL) circuit.
Ultimately, your high and low beam headlights are controlled by PCB 8 located in the front run bay. You’ll find detailed information related to the lighting circuitry in the 2007 Patriot Thunder Wiring Diagrams_Optimized.pdf (Coach Assist Section).
You’ll need review the diagram set as there are several diagrams depicting the various components and lighting circuitry. Here are a few.
Page 185 shows a good overall diagram of the headlights and fog lights circuits.
Page 107 shows the detailed schematic for PCB 8.
Page 99 shows the pinouts for PCB 8 as it is configured in the front run box. Keep in mind that, that the low and high beam labels are wrong in the earlier diagrams and the coach PCB labels (explained above), this can be confirmed by reviewing the same diagrams in the newer Marquis wiring diagrams.
The head lights and running lights are also influenced by the VIP Smart Wheel controller, example, the ICC flash feature and the activation of the windshield wipers. The low beam headlights are enabled anytime you activated the windshield wipers (expect the wash function), even if the high beams are already on.
Pages 175 and 191 of 2007 Patriot Thunder Wiring Diagrams_Optimized.pdf shows detail of the VIP Smart Wheel controller and how it interconnects with the headlights. There are also Smart Wheel publications in Coach Assist.
I would start with the ‘fog light’ test mentioned above.
Turn the ignition key to run.
Pull out the headlight switch.
Cycle the dimmer switch.
If the fog lights cycle ON with the low beam and OFF with the high beam MOST LIKELY the dimmer switch and steering column wiring is OK.
If not, you are going to have to do some probing with a DVOM at the various connectors and components to determine the issue.
Start at dimmer switch and steering column wiring, then move to PCB 8, then do the same at the VIP Smart Wheel controller.
Also, do your daytime running light work?
-Scott
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Hi Scott Thanks for the detailed info on the pcb board next time when I am in my Coach hopefully next weekend I will try and run the sequence I believe when I have the low beams on just the park lights are working but I will try the fog or running lights to see if they shut off when i hit the high beams. The tech did notice that I did have a burned out fuse or wire but I will need to check that also.
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Ok the fog lights are working on low beam and off when i hit the high beam switch also the low beams come on when i hit the high beam switch so something is going on will have to take it in for a tech to figure it out the running or park lights are working fine? Thanks for your help Scott will let you know once it is fixed.
Thanks
Paul
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Paul
The fog lights are designed to only work with the low beam head lights they should shut off when you turn on the high beams.
Eric