Author Topic: 76 450se ignition control module repair  (Read 254 times)

Kissel

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76 450se ignition control module repair
« on: 18 September 2020, 07:15 AM »
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
« Last Edit: 20 September 2020, 05:20 AM by Kissel »

revilla

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Re: 76 450se ignition control module repair
« Reply #1 on: 18 September 2020, 10:28 AM »
Hi
I might have a picture of the PCB.
Let me check.
Robert
W116 1977 280SEL & 1979 280SE

ptashek

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Re: 76 450se ignition control module repair
« Reply #2 on: 18 September 2020, 10:56 AM »
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
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE (history, resto)

Kissel

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Re: 76 450se ignition control module repair
« Reply #3 on: 19 September 2020, 07:29 AM »
I just attached a pic maybe someone can tell what it is

ptashek

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Re: 76 450se ignition control module repair
« Reply #4 on: 19 September 2020, 10:43 AM »
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.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE (history, resto)

Kissel

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Re: 76 450se ignition control module repair
« Reply #5 on: 19 September 2020, 06:06 PM »
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 .

ptashek

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Re: 76 450se ignition control module repair
« Reply #6 on: 20 September 2020, 03:09 PM »
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.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE (history, resto)

TJ 450

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Re: 76 450se ignition control module repair
« Reply #7 on: 21 September 2020, 10:29 PM »
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
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

Kissel

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Re: 76 450se ignition control module repair
« Reply #8 on: 22 September 2020, 12:56 PM »
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.