plug board

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bavagain

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I'm trying to get in front of potential electrical problems on my E3 project car. Looking at the wiring diagram for lighting i see a reference to plug board engine side and plug board passenger side. Where is this board located and is it a source of potential elecrical problems. Is it actually a board like a printed circuit board or just a physical connector with plugs to connect wiring from passenger side to engine side. any help, discussion appreciated
 
I think you will find that plug board reference may be the assembly that plugs into the back of the fuse panel in the driver's side glove box. Without seeing the diagram that you have, it is difficult to determine. There is a gasket through the firewall but no plug at that gasket.
If you are looking at potential wiring problems be aware there is an issue with models after 1974 with an unfused hot lead to the high beam under the dash next the low beam relay. It is wise to fuse this lead. (25A) If the relay return spring fails it is possible for the arm inside the relay to drop out of place and short this lead to the relay ground resulting in a harness fire.
The other thing that needs consideration is the original metal/ceramic ingnition switch. The red +12V lead to this switch is also unfused. If the ceramic gets old, cracks and separates from the metal part of the switch or the metal tangs become loose, the bottom part of the ingnition switch will drop out loose into the metal steering column. As BMW did not cover the soldered contacts on the bottom of this switch you have an extremely good chance of a dead short to ground on a heavy gauge unfused +12V lead. The simple answer to this is to drop the 4 bolt cover off the bottom of the steering column and either make a plastic cover to gaurd against a short if the switch breaks or coat the exposed red lead in a dab of silicon. Also a cool mod while you have the cover off is to cut a bit of blue or green film and place it in front of the bulb next to the ignition switch so it is no longer a distracting white light reflecting off your keys at night.
 
The plug board sits on the firewall just to the left side of the steerig column on models up to 73 I believe
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Thanks, I've go the Ball AutoBooks downloadable manual. My E3 is a 72 and is in driveable condition. The lighs are sketchy, no headlights and random taillights all of which could be as simple as a relay and bulbs. I parked it for the the winter because i dont have a heated place to work on it but weather is starting to break and I'll be back on it soon. Having worked on more than one British carl so when it comes to wiring I tend to go to connectors and grounds first. BMW's typically dont have many wiring problems the biggest being grounding, maintain good clean grounds and good to go. The wiring on this car has not been cut up so I feel like chasing electrical gremlins wont be much of a problem. I did install a new ignition switch so good to go there.

I'll certainly check any fused leads and will check the contacts on the back of the switch for potential to short. I didnt consider that when i installed the switch. Thanks for the info, anyother insights into potential electrical problems welcome.
 
Just took at look at my 1972 and 1973 Bavaria. Neither have this board at the firewall. The Parts book shows this plug board as part number 61131350480. The book also shows that it does not apply to USA BAV. Hope this helps if you don't find it.
 
As for your issues. What year is the car? Is the turn signal switch on the right of the steering wheel or the left?
Is it just the low beams not working? Do the high beams work?

A common issue with rear lights is using cheaper (Bubba's gas stastion) bulbs. The factory bulbs (silver bases not brass colored) fit better and the bottom contact of the bulb does not go soft or tarnish. I had a couple of cheaper bulbs I once bought and they became intermittent. I discovered the bottom contact was made of really poor lead solder and flattened out. Sort of looked like a dog that chases parked cars.
 
Thanks, I havnt looked to see if a plug board is present, i was studying the wiring diagram as provided in the downloaded Ball Autobooks and found where certain wiring was connected from the passenger compartment to the engine compartment by a plug board. I actually hope there is no plug board and it's like my 02 where the wiring harness is thru the firewall in a grommet. Something like a plug board just provides a point where corrosion may occur.

My e3 is a 72 the turn signal and wiper controls are on the right side of the steering column and the headlight dip switch is on the left etc. At this time the headlights do not work and some of the taillights work. I'll be chasing the causes as soon as i start work on it. I suspect it's a combination of burnt out bulbs and perhaps with the headlights a bad relay. PO had installed clear glass H4 headlights which i havnt tested. that will be one of the first things to look at, besides I'll be chucking the clear glass H4's for traditional fluted H4's.
 
The low beams on the 72 do not have a relay. They are also fused separately so if a fuse blows you don't lose both lowbeam lights at once. I would focus on the high/low beam switch as a possibility. There is a releiving relay that kills the power to the headlamps when the starter turns over but I've never had one fail. That doesn't mean it may be an issue. The other piece is the actual headlamp switch. Happy tracing.
 
My plan is to upgrade the lights but thought i'd try the clear glass H4's the po installed. Personnally dont like the look of the clear glass but I might get used to it. I know theyll need relays
 
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