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I achieved litte progress. Yesterday I managed to get right rear CV axle and ABS hub out from my donor. Maybe I can get the other side this week too. The ABS-ring has 48 teeth and I have to rebuild the hubs with new bearings, bushes and rotor backing plates.
So for now the front R129 hubs and the transmission speed sensor are missing in my parts collection. Purchasing the speed sensor is tricky because that part is not mentioned directly in MB parts cataloge. The red marked part is A126 271 0482. Is that the right sensor? I have my doubts but I will ask my MB dealer soon.
#413 is just a cover plate for the sensor like this:
Finding the part# from that sensor is really hard. I found out that the sensor in any w126 is part from the transmission wiring harness. Part# are A1265400909 (replaced by A1265407108). The sensor itself is very rare to get. Perhaps I must part out a whole w126 tranny.
Last edited by Benzdriver91; Apr 18, 2022 at 09:31 AM.
Sorry i forgot, the sensor is not sold separately, it is wired in the transmission harness, you can get it from all mercedes cars with 722.3 transmissikn that use speed sensor for the speedometer.
including R129, W140, w202, w124 (400e and 500e), w210 (early type with 722.3)
I found a seller on ebay who have it, it has part numbers and pictures, unfortunately this parts comes from R129 so its kinda expensive.
Please check attached image
Fortunately I was able to get that sensor as part of the transmission wiring harness from a w126 300SE (30 bucks). I checked possible locations at the rear of the tranny. But it is very less space betwenn sensor and 3-arm-flange so that interaction from the flange as a signal disturbing source is possible. Most likely I have to install the sensor at the propshaft.
For sensor installation in tranny housing: do you have a pic from the G-Class parking gear? Maybe you can remove some teeth so just four teeth are left. Unfortunately the serial 722.6-parking gear has holes which can disturb the sensor inducted signal (sensor is magnetic and I think it works like a inductive coil).
I dont know if it will work, because the G sensor needs a special relay, they called it ballast. While the 126 sensors connect directly to the instrument cluster.
yes they are magnetic sensors, they have same principles.
If you are planning to install it on the tail of the 722.6, you will need a plastic cap that cover the sensor, i think they have it on the epc diagram that you posted here.
Please keep in mind, this sensor function is only to drive the speedometer, so you dont need extreme accuracy. On G wagen it is used to determine shifting point so it has to be dead accurate.
Please fibd below attached image of the G wagen parking lock brake, it has 16 teeth that is not existed on other 722.6. the part number is different.
I bought it for $450 brand new, if im not wrong. I cant source a used one anywhere.
Oh i forgot to mentiom this, when i installed the speed sensor on the 722.6 housing on my G wagon, the sensor knocks on the transmission joint. Therefore i have to special order a transmission joint for G500 to clear the sensor, i would imagine this could happen to you, eventhough you manage to install the sensor there.
Hi, today I pulled more wiring out.
What is that small black reley close to EGS module for?
It's part of an other big wiring harness which goes from the module box in the engine bay back into the trunk to another module called RCL module:
Because this module controls all the door locks I assume it is better to have it together with the ECU and all other electronic stuff. I think I need the module to run the car...
Last but not least: I also have the blue ABS plug in my donor (but with two ABS-sensor cables, that's no problem. I have both rear wheel sensors and their wires out). What is the black-red wire for?
It goes into the fuse box, to light control module. Maybe reverse lights? And do you know what the other blue plug is for?
Invested 3h today. Very exhausting because a lot of important wires goes throught the right rocker panels which are compressed (perhaps by another angry car driver???). I purchased the car in demolished condition.
The front brake is very big: 320mm and maybe R129 calipers. If they fit onto w124 front knuckle?? MB says in comes from SL600. There is no AMG mark on it.
After the complete cable pull out just a few things are missing on my list: electronic speedometer, R129 hubs, exhaust system, anchor plates, steering box from E320, engine mounts & arms...
Last edited by Benzdriver91; Apr 29, 2022 at 04:30 PM.
That small relay is the ABS pump relay, you need that. It is connected to the body wiring.
the RCL module is not needed. If im not wrong its the central locking module which is not needed for the w124.
The black and red wires is circuit 15 for the rear reverse light, the rear reverse light is a very simple system, circuit 15 from fuse connects to the shifter there is small socket (2 wires) below the shifter, on the rear side, one is cicuit 15, the other is direct wires to rear reverse light. When you move the shifter to R it connects the 12v and reverse light is on.
MY advice : make it simple ECU, DAS, ABS, EGS use the W202, other wiring use the w124.
Why? Because the more you try to use the w202 stuff the more wiring you need to modify.
All wires that goes to the door is not needed, thats just for central locking, power window and illumination lights, speakers.
You need to remove the tape from the body wiring loom so you can separate them.
Again you need wiring diagrams, its so damn hard without it. (I cant find my diagram somehow)
i can help you but i cant remember each wires and color code.
The disc brakes wont fit, it has different hub size, therefore different offset for the wheels, different calipers mount. The calipers might fit with some modifications. there is somebody who did it on w124.
the link i gave you is shut downed, is russian web. I will try to find what i keep on my laptop.
What w124 do you have? E320 or something else?
exhaust you can use w124 E320 exhaust, direct bolt on. steering box is the same, if you want to go my route buy a sportline or 500E steering box, it has 3.1 turn lock to lock, so more sensitive steering, the regular w124 all has 3.4 lock to lock.
spedometer buy 400E or 500E, the problem with 400E speedometer is the calibration, it has 2.24 final gear in USA, 2.64 in Germany, 500E has 2.82 final gear so the speedometer accuracy will be affected according to your setup (not a major issue).
Good morning,
thanks for supporting me with that much information!!
Not needing the RCL module makes the whole thing a lot easier for me. I guess the two wires in the half of the 38-pin diagnostic plug from the RCL module are also not needed (green-white and yellow-black). I will use the whole diagnostic plug but without the RCL wires.
For now I have to work me through the wiring diagrams. This will took some days I think.
Speedometer calibration is a problem. E500 speedometer is quit expensive but the only one which matches the 2,85 diff ratio from my C36 donor. Maybe some R129 hase the same rear axle ratio, I will find out.
R129 speedometer is a completely different thing, it will not fit on w124 housing. Totally different system and electrical board.
you can use 400E euro version is 2.65 i think.
But dont worry too much, this is just for your eyes.
The signal from the speed sensor is dedicated to the speedometer only, its not used for ecu, abs or other things, So it wont affect how the car drives.
Ecu, abs, egs get the signal from wheel speed sensors.
There is this aftermarket product to correct the speed signal if you insist to have a dead accurate speedometer, some people use it for mercedes. Just search on google.
below is the link of the product.
Regarding the diagnostic plug, its 38 pin with lots of feature. But please realize that since we are doing conversion to modernize the car only for ECU, ABS and EGS, there is no point having all those wires.
If you are familiar with mercedes STAR, on older cars, when you diagnose ECU, ABS and EGS, it opens another software called HTT-WIN, this is the core of the car. So basicly as long as we can read these function, we are good
The rest of the PIN and wires on the 38 pin plugs is for body features, such as central lock, ac, radio, instrument cluster, lights, door module which in this case none of them is installed.
What i did to mine, i cut a lot of those wires away from the diagnostic plug to make the wiring much simpler.
Thats why you need wiring diagram for it, so you wil know which wires that is still used and what not.
Hi, slowly there are all parts came out of my donor.
Because the RCL harness: do you recommend to cut all RCL wires? All ot them?
I also noticed a thick black wire between module box and the SRS-module on the mittle tunnel. I don't need any SRS wires?
Do you know where all the ABS pump relay wires go? Two red/grey go to fuse box, also the black/white. But there are black/blue and black/green and I remember they could go into the sillars.
I also think about a plan how to use the C36 diff in w124 axle. Because that diff is the middle one with 185mm ring gear, its housing is smaller than the 210mm variant used by any M104 engine in the w124 rear axle. And also the axle frame would be wider than the w202 one. So I will end up using longer CV-axles and must press on the ABS impulse ring onto these longer axles.
Acc. speedometer it is almost a must to use some signal converter because the w124 E500 speedometer is very hard to find. When I use a signal converter I also can use the bolts at the driveshaft yoke as impulse teeth.
For RCL module, i think i did send you a diagram, from what i can remember, DAS module is connected to RCL module and there are so many wires here and there connects to the door locks etc. I cutted all of them, I only use use the DAS module, again, on the DAS module there are two plugs on one pf the bigger plug it has 12V, 15, ground, can C (green and green/white), the othet plug is 2 pin and is connected to the key ring.thats all i use. The central locking system is still using the w124 system, therefore no interference between two different cars. Very simple system.
ABS pump relay, i cant remember the colors but two of the wires goes directly to the pump, which is wrapped inside the ABS wiring loom
Differential, i exchanged many differential from w124, w202, w210, all of them are switchable, yes the w124 has 210mm diff, and w202 and w210 has 185mm, i can exchange them with no problem, it bolts directly to the chassis, but i remember there is one time the width of the diff is different, so i switch the side couping from the old diff to the new one. I cant remember which cars though. Its been a while, but there is no modification required, its just about switching parts from one to another.
SRS i didnt use any of them none, i threw all the wiring and module and i use the w124 SRS system. It has nothing to do with engine, abs or transmission. SRS is standalone system.
Again u need wiring diagram. I can help you with the system setup but i cant remember each wire color codes.
Engine mounts and arms get it from w124 E320, direct fit, i forgot to mention one thing, use your AC compressor from w124, dont use the w202, it has different activation module and wiring system. If you use the w202 you will end up installing the wiring from w202 ac which is comolete different system.
In order to do this, you have to get ac compressor bracket from the W124 E320, dont use the w202 bracket.
One more thing, cruise control, you can use the cruise control system from the 202, it is so simple, it is directly controlled by the ECU, ECU connects directly to the switch on the steering column, you can use the w124 switch, just remove the plug and just install the w202 plug, and connects directly to the ECU. Both switch has same wire colors so just follow the order on the w202 switch accordingly. You can remove all the unnecessary cruise control wiring and module from the w124 if you wish
My plan is to swap a 4-cylinder w124 convertible. So I need all the 320 specific parts too. For example front axle with brakes, steering, AC fan assembly and exhaust.
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