Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
No crank, no start, new starter, relays click, no fuses blown, ran a jumper wire for starter and it cranked but couldnt hear any priming or injectors wouldn't start. Swapped relays still nothing. No crank once jumper wire removed. Every few tries the fan will turn on. Sometimes I hear a couple clicks and sometimes just one when I turn the key to start. No previous issues. Common issue is fuse 52 was not blown but still attempted a large amp fuse such as 20 still no start or change. The obd2 scanner will not connect. At a loss ideas?
Do not have a similar car to swap parts. Do you think the sam itself could need replacing since the jumper wire worked? As far as scan tool, just a basic code reader from autozone dont have access to a better one but the scanner works on other vehicles just not communicating with the mercedes.
I dont think it is the sam, could be though. I have seen your scenario a couple times, the ME is the module and controls the starter relay. swapping ME is a sure test, but if you dont have one, you are kinda stuck, Also, if you did swap the ME and it started you need to code and new module and if you dont have that scan tool, ( xentry ) you are out of luck anyways. sorry but I would send this one to a dealer.
Found some more interesting things about this vehicle. Before the car broke down it always showed -35°C for the outside temp. Since it broke down it only shows 185°F and has never worked it's always been constant since I've owned it. Replaced the sam but now the radiator fan turns on high when I put the key in almost everytime was only doing it every so often before it was replaced. All new fuses and relays in the sam. New starter. Also pulled out the ecu and took it apart and cleaned it with electrical cleaner no residue and let it dry. Officially out of ideas any advice on the new items found? Pictures are before cleaned with cleaner looks tenfold better.
Looking at those photos i would have to say that needs replaced. Those solder points should look shiny to dull shiny in appearance. That looks like its been water damaged.
Replaced sam unit, replaced starter, just got a 1200 brand new programmed ecm, new alternator, new relays and fuses. Car still does a few clicks no crank no start. But when you run a jumper wire where the relay is it will crank. Ideas? Already installed new relay. Battery got tested twice on 2 different machines both read good and its fully charged. Right now im out of ideas and out of money.
Have you checked if your getting a start signal from ignition switch or signal from bcm to pcm? Do you have a subscription to Mitchell or alldata? This will help you trace the issue faster than no wiring diagrams.
