Anyone have a schematic diagram for the Bosch Ignition Control Module?

I'm in the process of designing an interface between the Bosch distributor and a capacitive discharge unit that was designed for points. Does anyone have a schematic diagram for the Bosch Ignition Control Module? I'd like to see how Bosch does the interface to the reluctor coil.

Thanks,


Don
 
This is very old technology. I've already made up an alternative that's very affordable that will fit inside the Bosch control box and uses half the current while supplying a superior spark to the plugs.
The write-up is HERE but there are folks (possibly Jeff Nolta) here that make these as a service. The price is quite low as compared to buying a new Bosch and the results are better when compared to performance, current consumption and price. And the coil runs cooler as well. :)
 
This is very old technology. I've already made up an alternative that's very affordable that will fit inside the Bosch control box and uses half the current while supplying a superior spark to the plugs.
The write-up is HERE but there are folks (possibly Jeff Nolta) here that make these as a service. The price is quite low as compared to buying a new Bosch and the results are better when compared to performance, current consumption and price. And the coil runs cooler as well. :)
Hi Bob:

Yes, I already checked out your excellent upgrade article. If I actually had a Bosch ICM, I might go that route. However, all I've got is the Bosch distributor that came with the '79 1500 I put in my 74. I thought about getting one of those GM modules and building my own box. I rummaged through the basement and found three old capacitive discharge units including one I designed and built for my senior thesis in 1972. I pulled out an old Delta Mark 10B that was in the car at one time and worked well. On my test setup, it delivers about 450V to the coil primary. That is likely better than I would get with the stock Kettering system at high rpm or cold cranking. Since I've got a good working CD unit, I thought I would try using it with the '79 Bosch distributor. I need to recurve it first, as it has too much advance, and it comes in too late. Something closer to the FI version would be a better starting point. I recurved the '74 Ducelier distributor that is currently in the car but it seems to have lost its advance stop in the 30+ years since I did it. I could fix the advance stop, but thought it might be fun to play with the Bosch distributor and get rid of the points.


Don
 
Don, if I'm understanding correctly you are wanting to use the Bosch electronic distributor to trigger an aftermarket ignition and not use the Bosch ignition control "box"? If that is correct, then how the Bosch control box works or how it's circuits are configured should not matter, because that is a separate function from the distributor's triggering (VR). There was a good technical description of how the distributor VR functions a while back (sorry I don't have a link). But try searching that rather than the ignition control unit to see if it comes up. Also, the same Bosch VR system was used on millions of vehicles for decades, so you may also find some good info on it under German vehicle sources online. Wish I could offer a more technical answer, but hopefully this will help steer you to it.
 
Yes, you have got that correct. The reason that I would like to see the Bosch schematic is to examine the input circuitry. Without that, I need to do a bit of electrical characterization of the distributor output. It is just a bit more work. I did a search as you suggested but so far the results seem to be bringing up the Bosch systems that use Hall Effect sensors. Do you happen to know the Bosch part number for the X ICM? That might result in the most relevant search results.
 
Yes, you have got that correct. The reason that I would like to see the Bosch schematic is to examine the input circuitry. Without that, I need to do a bit of electrical characterization of the distributor output. It is just a bit more work. I did a search as you suggested but so far the results seem to be bringing up the Bosch systems that use Hall Effect sensors. Do you happen to know the Bosch part number for the X ICM? That might result in the most relevant search results.

The Volvo 240 series of the late 70s used the same impulse trigger setup. You could look up for say, a 1979 244 2.1l with K-jet. I don't recall the name of the ignition system but I may have a Volvo ignition system design & function manual that includes it
 
Pics I have for you:

IMG-20190912-141025.jpg


IMG-20190912-141031.jpg


Later manual I have only covers 700 series, which only had early V6 still using TSZ ignition

IMG-20190912-141204.jpg


IMG-20190912-141209.jpg
 
The Volvo 240 series of the late 70s used the same impulse trigger setup. You could look up for say, a 1979 244 2.1l with K-jet. I don't recall the name of the ignition system but I may have a Volvo ignition system design & function manual that includes it
Interesting. I used to have a 78 244DL. Too bad I gave away all the technical manuals with the car!
 
Pics I have for you:

Later manual I have only covers 700 series, which only had early V6 still using TSZ ignition
Thanks for the diagrams Hussein. In the first photo, just to the right of the red "A" is a rectangular box. Finding out what is in that box is my goal. I have a couple of options if that does not pan out. One is to chuck up the distributor on the bench to a drill and check the output waveform versus rpm and load resistance with an oscilloscope. That would provide the needed info to design a circuit. I may want to do this anyway to check out the system once it is complete. The other option would be to find the schematic for the GM module or one of it's clones since we know they work with the Bosch distributor.
 
Thanks for the diagrams Hussein. In the first photo, just to the right of the red "A" is a rectangular box. Finding out what is in that box is my goal. I have a couple of options if that does not pan out. One is to chuck up the distributor on the bench to a drill and check the output waveform versus rpm and load resistance with an oscilloscope. That would provide the needed info to design a circuit. I may want to do this anyway to check out the system once it is complete. The other option would be to find the schematic for the GM module or one of it's clones since we know they work with the Bosch distributor.

I see. so you actually need a circuit diagram for how the chip in the module handles the I/O? If you just need a pic of the guts, I have several of these. Schematic of the circuitry I can't help with.
 
Don, the Bosch part number for the control module on a X1/9 is: 0-227-100-029.

As for the distributor's output waveform and specs, that can be found in the literature that Bosch published years ago when these were still new. I would imagine it is somewhere on the web by now, seems I've run across it a time or two over the years.
 
I'm in the process of designing an interface between the Bosch distributor and a capacitive discharge unit that was designed for points. Does anyone have a schematic diagram for the Bosch Ignition Control Module? I'd like to see how Bosch does the interface to the reluctor coil.

Thanks,


Don
I can't help you with a schematic, but Rolf Grumme posted a scope plot of the output waveform in this post. I went through the exercise of simulating the reluctor output in Excel a while back, but I can only find the plot, not the data:

image001.gif
 
I see. so you actually need a circuit diagram for how the chip in the module handles the I/O? If you just need a pic of the guts, I have several of these. Schematic of the circuitry I can't help with.
Yes. I am guessing that there is an amplifier/comparator function in there that switches the power device. Do your photos show enough detail that I could pull a schematic off them?
 
Don, the Bosch part number for the control module on a X1/9 is: 0-227-100-029.

As for the distributor's output waveform and specs, that can be found in the literature that Bosch published years ago when these were still new. I would imagine it is somewhere on the web by now, seems I've run across it a time or two over the years.
Thanks. I will check it out.
 
Any idea of what the vertical scale is or the load conditions? That might do the trick.
In my plot I made no assumptions about the magnetic flux nor the number of windings in the reluctor coil, so no meaningful values on the x-axis. In Rolf Grumme's plot, you can see he is getting roughly 16V p-p at 911 RPM (note that this is from a 6 cylinder engine, in case you are trying to relate RPM to measured period). The voltage would be proportional to engine speed, so your input stage has to survive fairly high voltages.
 
In my plot I made no assumptions about the magnetic flux nor the number of windings in the reluctor coil, so no meaningful values on the x-axis. In Rolf Grumme's plot, you can see he is getting roughly 16V p-p at 911 RPM (note that this is from a 6 cylinder engine, in case you are trying to relate RPM to measured period). The voltage would be proportional to engine speed, so your input stage has to survive fairly high voltages.
I first read the message with the plot on my phone and missed the link to Rolf's plot. After seeing it, there appears to be a fairly good size signal. I wonder what the load impedance is? If it can supply just a little bit of current, it should not take much of a circuit to do the interface.
 
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