Hi , my 76 450se decided not to start the other day and I could not get spark. Out of curiosity I opened the ignition controls module and found that one of the resistors was burnt ☹️ After looking at the prices or new and rebuilt ones I want to take a shot at repairing it first, but I have no idea what the burnt resistor was or what it looks like. I tried to find a picture of an open one but no success. Does anyone have a picture of one open or is willing to take a picture of theirs ?
Thanks in advance
Hi
I might have a picture of the PCB.
Let me check.
I've reverse engineered the whole thing a few years ago.
Here's the complete schematic: https://www.circuitlab.com/editor/#?id=5ag5z6
Page four in the thread below has all the pics:
https://forum.w116.org/mechanicals/reverse-engineering-the-bosch-k-jet-ignition-module
I just attached a pic maybe someone can tell what it is
Ah, it's the simpler, older module. Going by size alone, it's likely a 2-watt part. Being close to the power transistor (and judging by some of the visible traces), I'd hazard a guess the resistors job is to limit the base current. But the band colours are burnt off, so it's anyones guess as to the exact value. In the newer circuit that I have linked to, it would be 330 Ohm.
Thanks , I am Afraid to install the wrong one. I have pulled another unit from one of my 450sl's and when I opens it unfortunately it was different .
I guess the question is, whether your car is D-Jetronic or K-Jetronic. Being a 1976, it should be K-jet so If you install another module from a K-Jet W116 it should just work, but it's your call to make. Personally, I'm not aware of any differences in the ignition system that would prevent the newer module working.
The internals have changed to the more complex module, as linked above, from chassis number 045340 (450SE), which - going by data in the parts catalogue - would be the first K-Jetronic chassis number after D-Jetronic was done away with in July 1975 [1]. It was given a new part number, which is the only one Mercedes still supply as a refurbished part at a cost of around 1200EUR. These newer modules are extremely reliable.
The old part number was A0005458432, and the new one is A0005457632.
[1] The last D-Jetronic 450SE was chassis number 045339.
The modules from all the K-Jet models including the W123 280E are the same through to the early 1980s. If it is in the same package it will work fine.
Tim
Thanks You guys are a great help !!! I am going to try to put the one from my tan 450sl to see if it works. I still would like to save the old part , even if it is just for a spare.
new here, I was searching on how to remove the WUR plug retainer clips for testing and found your site
I have a 79 450SL it is a different box but it might help others, this is from a junkyard pull, and it was running for at least 20 mins and 5 miles around town
(https://lh3.googleusercontent.com/3_x6LqnLiHHdcmOUe7E1QEg5UYzTXVR_2BwReJtK2a2sKmUEJwcl93F6sSryr3wW96rbRcSbB2cuo-lN5w=w252-h220)
obviously totally different box, and too small to be useful/readable, bosch 0227 100 001B , and a K jetronic -aka mechanical, no 02 sensor-
for D-jetronic check the german site,
https://jetronic.org/de/
they have an english section
https://jetronic.org/en/
Quote from: letankoid on 03 March 2021, 07:50 PM
new here, I was searching on how to remove the WUR plug retainer clips for testing and found your site
I have a 79 450SL it is a different box but it might help others, this is from a junkyard pull, and it was running for at least 20 mins and 5 miles around town
(https://lh3.googleusercontent.com/3_x6LqnLiHHdcmOUe7E1QEg5UYzTXVR_2BwReJtK2a2sKmUEJwcl93F6sSryr3wW96rbRcSbB2cuo-lN5w=w252-h220)
That's the later version, mentioned in an earlier post.
Full details + reverse engineered schematic: https://forum.w116.org/mechanicals/reverse-engineering-the-bosch-k-jet-ignition-module