One morning I started my car and realised both my wipers, my horn and my SRS airbag system had failed all at once! Imagine the nightmare..
Thankfully no other errors showed up but I essentially went straight to my garagist who works at Iframac (local mercedes service centre mauritius). From his initial tests using the STAR diagnosis (software that runs on a laptop which is in turn connected by a cable to the car computer)
After several hours of troubleshooting the STAR diagnosis software estimated that the SAM unit had failed. SAM stands for Signal Acquisition Module basically a circuit board located under the bonnet that deals with sensor readings and actuating motors etc in the front of the car
Realising that such a unit costs Rs 14 000 local mauritian rupees, (205 dollars USD) I decided not to be in a haste and investigate the matter further myself.
Your best friend is you guessed it Google. I managed to download a PDF showing the actual board topology for a SAM unit and I realised one thing. The whole board is populated on its upper surface with Relays !
On further inspection something came under my eye.. highlighted above is a description of the N10/1149 relay that is responsible for SRS controls (Restraints control system)
I pulled out the front SAM unit and began inspection on the underside of the board for damage, there wasn't any (thankfully)
I retraced the N10 relay which is infact the gray box next to the two yellow ones
I pulled it out tested it using battery voltage and weirdly wasnt closing well... it took a second or so to close. something strange actually because relays are supposed to close instantly when powered
I tried my luck and bought a 12 USD dollar Relay from mercedes service centre (Iframac that time)
As soon as i replaced the relay everything was back to normal again all fully functional! That saved me well over 190dollars :)
Hope you enjoyed this post, keep on hacking :)
