Mercedes Fuse Box / SAM Replacement, Windshield Wipers
A shop had a car that wouldn't crank when the key was turned but started if the starter circuit was jumped. The front SAM was faulty, but when it was replaced the engine still wouldn't crank with the key and it no longer started when jumped. Additionally the wipers quit working
The issue was simple - the new SAM came with some fuses missing, the fuses for the ME. The wipers didn't stop working, they just don't work whenever the hood or driver's door is open on most MBs since the 203 chassis, something that is not well known by shops that don't work on a lot of Mercedes.
Always compare the new and old SAMs, sometimes fuses and even relays are missing. Also, for authoritative information on fuse location, assignment, amperage, circuit, and consumers, see group 54, subgroup 15 in WIS. (Attached).
I've learned that the hard way myself! Working on air suspension with the door open!!
I have one a W203 in here now with a no spin no start. ME and front Sam sitting in water that came from the carwash. He's calling the carwash to see if they'll pay for it since it happened there!!
Great Tip Andrew about fuses not being fitted to the SAM that would definitely catch some Techs out. A lot of Euro cars will not allow the wipers to work when a bonnet is up.
Not long ago my tech tried to bled the fuel after replacing a fuel filter and could not turn the lift pump on in a VAG Diesel Golf. The scan tool reported select P/N we are thinking what is P/N it took a while to realise it was Park / Neutral. The selector was in N but for some reason the ECU did not recognise the selector was in neutral and as soon as we selected park we could than operate the lift pump.
On vehicles like this will the engine crank if you close the latch with the hood open or are there other switches involved?
I think Andrew was making a general statement about front SAM replacement. When you replace it you make sure all of the functions work before you release it to the customer.
If you're chasing a wiper problem then trip the front latch before testing or you're always going to have to no trigger to the motor as your diagnosis!!
I was just asking a general question on the hood operation. It is as simple as closing the latch to defeat to no start strategy or are there other measures that need to be taken if you want to crank the engine with the hood open?
Hi Bob, the engine will start and run with the hood up it is just the wipers that will not operate until the hood is closed, possibly so the wipers will not get caught up on the open hood.
Guys just a bit of trivia, down under here in Australia we call the car roof or turret the hood, and what you call a hood we call it a bonnet. What you call a fender we call it a mudguard, what you call a gas pedal we call the throttle pedal. What you call a car trunk we call it a boot, You call a ground we call it an earth, we call our car fuel, petrol you call it gas. what you call a wrench we call it a spanner, what you call a star screw driver we call it a phillips head screwdriver. But I hear you guys only have left handed screw driver we down under only have right hand screw drivers. You also drive on the wrong side of the road. So guys what hope do we have down under when you do not speak the different language and drive on the wrong side of the road. lol