BAC RV Club Forum
General Boards => Technical Support => Topic started by: Vince Toscano on November 08, 2026, 04:42:38 PM
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2003 Beaver Marquis,
11/13/2026
12 VDC, Front Run Bay Electrical power Chassis-Dash Controls
We had electrical issues during our recent 2026 summer RV trip from WA to Pennsylvania and return. While doing a pre-exit check before leaving a campground, we found that our turn signals didn’t work. As part of our investigation, we contacted technical support, partly because electrical chassis drawings for a 2003 Beaver are not available.
Here’s what we learned as we started to investigate. The turn signals, cruise control, wipers, and lighting controls originate at the steering column. The steering column has 2 aspects of signal transfer to the actual devices (e.g., turn signal lights, cruise): 1) communication cable and 2) hard wire. Communication cable is a 4-wire connector that goes up to the steering column to the clock spring (underneath the steering wheel). The hard-wire aspect is directly powered from the 12V front run bay. [On a 2003 Beaver Marquis, this bay is accessed from the outside and is beneath the drivers seat.]
The Communications portion begins with the steering wheel switches located on the steering wheel (see photo). The switches (i.e., cruise, wiper, and lights) are connected to a control board located in the middle of the steering wheel. The control board connects to the clock spring, beneath the steering wheel. The clock spring is actually a coiled ribbon cable. The connection the other side of the clock spring connects to a 4-pin connector at the bottom of the steering column. From the 4-pin connector, the wires connect to a control module. In our case, the control module is located inside the side panel to the left of the driver’s seat (underneath the transmission control panel). This control module converts the communication signal to the different functions (again, cruise, wipers, lights, etc).
Back to the turn signals. Below the steering wheel are the 2 switches that are for your turn signal and the 4-way flasher (i.e., hazard flasher). These 2 switches are physically a single component fastened to the steering column. The power side of the turn signal/hazard switches comes from an electronic flasher unit (a separate module). The other wires that come from the turn signal/hazard switches goes to 12V electrical front run bay. From the run bay, the lights are connected to a terminal strips within the run bay. From the terminal strip, the wires run to the respective lights.
The electronic flasher unit is a cylinder that’s about 1 inch in diameter and about ¾-inch high with 2 terminals at one end. The terminals are marked with “L” and “X”. L is the load side and X is the controlled pulse output for the turn signals and 4-way flasher switch. The power connection to X comes from the 12V electrical run bay circuit breaker. The Flasher Unit always has 12V power applied to that X terminal. The load side, L, splits to the turn signal switch and the 4-way flasher switch. Theory of operation for the Flasher Unit: even though the unit always has 12V power, the output does not pulse until the lights (i.e. load) are connected to it by activating either of the switch (turn signal or 4-way). Said another way, the Flasher Unit is simply what provides the pulsing action. See my hand sketch for reference.
During our trip, as I began trouble-shooting our turn signal issue. I began by using all resources to understand the system, but there was no available information. I first testing the X side of the Flasher Unit using a meter and it showed 12V of supply power. As soon as I used the turn signal switch, the 12V reading would go away on the meter. This lead me to 2 separate thoughts: we either had a short or an open (or broken) circuit somewhere. This was compounded by my lack of understanding on how the Flasher Unit worked in this application. I then disconnected the Flasher Unit in order to understand and test its operation.
My next step was to jumper 12V to the individual turn signal lights at the terminal strips in the front run bay. I found that the right- and left-side lights turned on as I applied power to them, telling me that the issue was not with the lights or the wiring. While in the front run bay, the next step was to connect the X side of my disconnected Flasher Unit to 12V power in the front bay and the L side to the wires on the terminal strips leading to the left and right-side lights of the coach. The lights pulsed as expected as if I was using the turn signal or 4-way flasher switches. At this point, I knew that the wiring and lights were all working, as well as understanding that the Flasher Unit worked only when a load was applied to it and it has a consistent 12V to it.
Next step was to take the Flasher Unit back inside, make jumpers, and connect the X side to a known good 12V supply. Then, with the jumper, connecting the L side of the Flasher Unit to the connector of the Flasher Unit that goes to the turn signal/4-way flasher switches. I then conducted a system test. Turn signals and 4-way hazards all worked as they should. Making these changes we were able to continue our journey. Just to add, being on the road I did not want dig deeper to interrupt our journey with any more unexpected surprises.
At home base. The search for the why. Between the dash and the 12v electrical bay are 4each connectors having 24 wire each. Located wire for the power to the Turn/hazard light. Opened the connector to find that all the pins and sockets were badly corroded including the pin and socket to the flasher unit. Note: When troubleshooting, using a meter does not put adequate load on the circuit which shows a false voltage reading versus a automotive test light does put a load on the circuit.
Attached are pictures showing the extent of the damage of the connectors from years of corrosion.
Path forward: Removing the connector all together. Connecting the wires to each side the connector. One at a time to ensure accuracy, needs to be 100%. What I settled on is a bare butt connector and then soldering. Using heat shrink designed for the marine industry.
P.S. can't attach pictures, if needed I can send them to you.
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Vince,
Good explanation. I'm curious as to why you didn't try using a good contact cleaner on the connector before jumpering around it. Corrosion will increase the resistance and can reduce/kill the 12V supply to the flasher.
Steve
https://ricksfreeautorepairadvice.com/how-a-turn-signal-flasher-works/
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Thanks Steve,
I wished that there was room for the pictures of the connectors. All four connectors that come down the left side of the 12v bay were really corroded. The other issue any high current circuits deformed the plastic around the sockets. I can send pictures.
Thank you,
Vince
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Vince,
I am confused about your issue. The clock spring only communicates the information that is located on the face of the steering wheel. Example: cruise control, wiper control, blink headlights and blink marker lights. The turn signal switch to the best of my knowledge is independent of the clock spring. Starting in 2003 Monaco (who built the coach) supplied a complete schematic of all wiring that came with the coach when it was delivered to the dealer. There were a lot of technicians at the dealers who would grab them while performing a PDI (pre-delivery inspection) and add them to their personal library to help diagnose electrical issues on customers coaches. Sometimes in the steering column right near the pivot that adjusts the tilt assembly, the connector for the turn signal harness gets pulled slightly apart if the steering wheel is allowed to jump towards the dash cluster. If you have a tow vehicle, I would unplug the car and check the 7-pin plug connector for power at the pins in the 3:00 position and the 9:00 position. if no power there, I would check all the output connectors on the boards located at the front run panel. Fred
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Hi Fred,
You are correct, the clock spring it's only function is for cruise,wiper and lights. The only reason I brought this up is when I inquired at a RV repair facility I was pointed in that direction. Primrose Path, sorta speak. The only drawing I was able to find is for the coach side and not the chassis. All my inquiries to different places, no joy.
In any event this problem with the turn/4 way lights exposed the issue with the 4 connectors in the 12v bay. Like the side marker lights tied to the turn/4way never worked, now they do. The dash fan actually increased the volume of air.
Something else Sometime after we purchase the coach (2019) there was information about the headlights operating very dim. There was a fix for this issue by adding some additional relays and a different power source. Looking at the 4 connectors and finding the wires for the headlights this to was corroed and the plastic was charred.
My hope is this information will help.
thank you,
Vince
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Hey Vince,
Thank you for joining the BAC forum. Your input was very thorough. We look forward to further discussion as we navigate these special Coaches from a by-gone area. Blessings, Fred
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When my headlights did not work all I had to do was trace the wire in the outside run bay under the drivers seat to the connector, unplug it and reconnect it several times and the lights work for a couple of years.
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Hi David,
I assuming that you took apart the connector associated with the headlight circuit? What was the condition of the pins and sockets of that connector? I wished that I could have posted the pictures of what I had found on out couch. I can send pictures.
Thank you,
Vince
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Thank you, Fred. You are most gracious. Blessing to you.
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Here are photos of the bay and the offending connectors. The corrosion was caused by a leaky drivers window which REV RV Group repaired. Its hard to believe they are still working.
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Hi David,
Yes the photo of the connectors are bad. Did they look at the other 3? There are 2 more in the upper right corner. These are of a different type more on the marine style because they have internal and external seals. When I took those apart all I did was cleaned them with electronic cleaner. The one that has the majority of the wire you may have to replace the o-ring. I did because the o-ring was deformed.
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David,
When mine started acting up I used electrical contact cleaner along with small round soft bristle brushes and mig welding tip cleaners along with carb jet cleaners. After scrubbing everything a couple of times I put a dab of dielectric grease on the tip of the pins and then on both sides of the connectors forming a water tight seal. I did this to all the plugs below the drivers seat area.
That repair worked for me for close to 9 years until I recently sold the MH, and as far as I know it is still working. Hopefully yours can be repaired as successfully.
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Thanks for the cleaning information, I will do that eventually. Everything is working properly right now so I don't think I will fix it until it breaks.