octawic baldemar ransome
Coleman John
Does anyone have any information on this particular Bosch ignition coil for BMW. The part no. is 12131712219. Tried googling it but was couldn't find much info. I would be really grateful if anyone here can help me out.
I wanted to give an update to this answer. I didn't go ahead with the wiring mentioned in this post as I wasn't fully confident if that is the right one. Also I was concerned that it might damage my ECU if I wired it wrong especially since this has high voltage present.
I had contacted the Bosch Global team but they could only get me a catalog and other data for the coil, nothing related to pinout. Next tried contacting the Bosch USA but they just directed be to their Bosch India Auto parts, yet to hear back from them after to weeks. Finally I contacted their Middle East team who told me they would contact the engineering team and get back with the pin-out. After a week finally they have provided. Here is the correct pin-out from Bosch:
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Hello Bimmers. I am no mechanic but I am trying to understand my dear '02 better. Last Spring she failed to start and I think the coil may have been burned out due to incorrect wiring. So I replaced it but have not tried to start it yet for fear of buzzing it.
I am unclear after looking at the wiring diagram, where the additional wires go. It appears I have one black (ground), two green (pos?) and two green w/ red stripe that are all looking for a place to go. See pics below.
The positive lead connects to the terminal on the coil marked with + sign, the terminal marked with the - sign connects to the distributor. I noticed you are using a Bosch blue coil; this coil has an internal resistor intended for use with points. Be sure that with the ignition switch in the run position that one of the leads has 12 volts. I hope this helps.
Don't mean to hijack this thread but I just ordered a Bosch blue coil for use with Pertronix. Since Pertronix has no resistor, should I stick with the black coil? Or is the blue still okay? It seems there's still confusion about this.
I've been trying to help a new 1917 Maxwell owner revive his grandfather's car and am having a wiring problem. This car should have a Simms magneto but his grandfather put a Bosch DU 4 on it and I'm totally out of my element. Most I find online have 4 terminals and this one has 5 with the fifth having a wire running to the front . I found a set of pictures showing this same wire but it doesn't look like something the factory would do. Anyone have any idea why it would be done?
Dave is correct.........it made sense for stocking purposes to just sell the dual instead of the single. The DU4 is the most common and reliable magneto ever made.....it should be easy to service and find parts. There are several well known rebuilders, most are busy and weeks to months out.......
My main question is do we just replace this jumper wire as it is, connect a kill switch and go ahead and try to start it? I'd really like to understand why the jumper would be needed and what purpose it served.
Your diagram seems to indicate a solid wire. All the ones I found seemed to be dotted lines which I'm not understanding. I also am failing to understand the 4 and 5 terminal caps. Your pamphlet shows 4 terminals and is American Bosch which I think was after WWI and the 5 terminal caps like my friend has seem to be prewar.
Your schematic's have shown up on other searches I've done and they all show switches and coils that apparently my friends Maxwell wasn't equipped with so we are wondering if his solution was the wire in question simply replaced all that and allowed the magneto to be used as it's own ignition source?
To someone who fully understands electrical systems completely this may seem to be a stupid question but we don't understand and are trying to revive this car with out burning up rare and expensive parts while doing it.
Howard, I am just going by the posted diagrams so take this as an educated guess... The wire you reference is the equivalent of a modern "coil wire". It is needed and if you need to replace it I would use a solid core spark plug wire.
I believe Roadmaster is correct. For your purposes you need that wire to the center terminal as the spark is generated on the tower at the drive end that the wire connects to. Some have a solid center connector to the rear of the distributor gear and only have 4 terminals for the spark plugs.
Unless there are other issues, I am not aware that that wire would even be used or needed. The 5th terminal would be used in conjunction with a standard 6 or 12 volt automotive coil, or Model T coil with bridge tied down for starting on battery.
Here is the published information on the 1917. Not much compared to other years. Notice it has an additional component tied in with the magneto and may be why something is jumped or bypassed. 12 volt car......interesting. Not much published on Simms........but they are so basic that it shouldn't be any trouble.
I believe the Simms was built under license from Bosch, and is basically identical to the DU4 in a four cylinder configuration. I have a Simms on the shelf and even think it says Bosch on it somewhere.
The 5th terminal does not have to be used, the magneto should work fine without it. Unless, the rod that goes through the magnets to the other end is missing/damaged. That rod assembly is what carries the current to the front, point end. The 5th terminal on the cap is there IF you wanted to use battery/coil to start the car, then switch to run off the magneto. The kill wire would be connected to the cap covering the points terminal. If you look at the one I posted the link to, you can see at rod looking piece.
I'm going to try to express my concern one more time. Like Mark I fail to see why this wire is needed. Edinmass, the car in question has had the original Simms magneto replaced with a Bosch DU 4. The original Simms magneto, unlike the Bosch was NOT able to spin fast enough by the starter to generate sufficient spark. That problem was solved by an intensifying coil and dry cells until the engine caught and reached a high enough RPM for the Simms unit to take over and run the engine. Those parts of the system were long gone over half a century ago when the owners Grandfather replaced the Simms with the Bosch magneto. That intensifying coil is something I have only seen one example in over 30 years of hunting so that route is not an option. All we want to do is get this car running again in it's current configuration as his Grandfather was able to do back in the 1960's. BUT I want to fully understand how and why he was able to do this modification before I tell the new owner to hook up 2 6 volt batteries and hit the starter switch.
This is why many cars etc not having duel sources, using magnetos, are equipped with an impulse coupler. It is a device that has an internal spring and latch. When the spring is wound while cranking and the correct spot is arrived at, the latch releases, allowing the rotor to spin faster, generating a stronger spark.
In going back over this to decide how to explain what to do to the new owner I think I stumbled across one answer to my very first question. Mark mentioned he didn't see any reason for the wire unless the connecting rod # 14 was damaged. I went back to my first picture to illustrate what I was talking about and noticed the rod wasn't damaged it wasn't even there! So I plan to have my new friend check first to see if his is missing as well and if not is it broken or corroded and won't pass current.
Hi George, Any chance you can email me a copy of this as I cant read it when I zoom in and I am looking to rewire a Hudson 33 Magneto that has been removed? This is the schematic that I have been looking for. Thanks in advance. Mathew
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