Hello everyone,

My title explains why I’m here. Unfortunately, my 04 S55 AMG, 109k miles, is giving me a problem that I can’t seem to solve with the ABC system. Randomly, but very often, I get code C1125, causing the red ABC light and the car to ride rough. The scanner states-

Fault in component 'B24/12 (Active Body Control (ABC)
Lateral Acceleration Sensor (LAS))'

i believe I previously saw on the scanner that I had an open or short circuit, but this may be incorrect. I can’t seem to find this code online so I’m not sure.

This sensor is located on the transmission tunnel on the driver side (LHD) and can be accessed from the interior by removing the carpet. I swapped out the sensor with a new one from the dealer which did not solve the problem, and I changed the module twice with two used known good ones, one of them being a spare that I had from another one of my cars. I know that the wire being broken is very unlikely as it runs under the carpet with many other wires, but I haven’t ruled it out. Regardless, can anyone weigh in? It used to happen maybe once a week and if I would turn the car off and restart, the red ABC light would go away. Now, I can’t even clear the code.

Any tips or suggestions would be greatly appreciated. This issue has bugged me since I bought the car a few months ago and seems to be the only one I cannot resolve.

Thanks in advance

 

Anyone?

 

It would be difficult to know where to begin given what you have said. You could check for bad grounds or a battery issue. Without other data it is all guesswork. Good Luck.

 

I’m having a rough time with this… replaced the sensor again, seemed to have solved the issue. I plugged the sensor that was used to replace the original in at the left front (same part number) and immediately got a warning light for it. Thought all was well after I swapped it back (now I had the original left front acceleration sensor and a SECOND new lateral acceleration sensor) plugged in. Kept shutting the car off and restarting, and no codes came up. Did this about twenty times and eventually decided to reassemble everything. As soon as I reassembled I started the car to make sure everything worked, and the red ABC light immediately turned on, you guessed it, c1125, fault in component b24/12. I disassembled again and hooked up my scanner, and found something odd. The voltage reading that I had previously gotten was 2510, which was consistent with all of the other sensors. When I had the new sensor plugged in but not bolted down, it maintained this number, but when I would turn it sideways and bolt it on so it wouldn’t dangle, it would immediately drop to 1600 and sometimes go as far down as the low 200’s. Because of this I’m leaning toward a wiring issue, but I am by no means a wiring expert at all, so I was hoping someone could chime in. I can’t find a pin out diagram of the ABC module anywhere, so if anyone could provide one that would be helpful. Once I do that, can I simply run new wired to the connector? I’m thinking one of the wires is making contact sometimes but has break somewhere causing it to lose its connection. The only thing is, the fault pops up immediately when I start the car, the car does not have to be moving. I’m really stumped at this point and have never experienced anything like this. I very much enjoy driving the car when the fault is absent and would say its probably the best driving car I’ve ever owned, even over my SL55, but this issue is bringing me to the point of wanting to sell its which is a shame for an otherwise perfect car. Any and all suggestions are greatly appreciated. Thanks in advance