When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Turned my situation from bad to worse. Needed to pump gas out of tank, so I connected line to fuel rail and with the key ignition positioned to on, the fuel pump would turn on and pump slight amount out. Went to bypass the fuel pump relay under hood and I must have shorted the connection. Saw it arc at the relay location, now fuel pump doesn't turn on.. engine won't crank... my key fob lock/unlock doesn't work, possibly other various things. I checked the several fuel pump fuses under hood & trunk - didn't find any blown fuses.
Did I just fry my ECM or another module? Shouldn't there be a blown fuse somewhere? How can I trace issue?
Thanks
I'm not sure what year your vehicle is, but on the 2008 there is a 20amp fuse for the fuel pump in the right side trunk fuse box. Ask me how I know LOL. My fuse blew and I spent a better part of the day removing the rear seat to get to, and test the pump relay and pumps only to find the fuse in the previous mentioned location was blown.
Wish it were just a fuse, but I checked each fuse in the front panel under hood and also the one in the trunk. Each fuse had continuity with my multi-meter.
I am suspecting the front SAM module might have shorted. But want to test this before buying a new one.
I have a 2010 C300 - M272 engine w/manual gearbox =)
Maybe one of the fuses in the pre-fuse block???
That’s based on your comment that there are multiple things not working.
It’s fairly easy to access and test the fuses. If there is a blown fuse, they can be replaced individually, are available online, and are very inexpensive.
Like OddPiggy said, prefuse block located just anterior and medial to battery cover, where + boost connector located..4 snaps hold black cover on. Amazon link points towards this fuse/possible source. I personally have buggered things up electrically and have yet to cause one of these prefuses to melt despite my best attempts !!
Thank you guys! Exactly what you two were saying - the Prefuse Box!! Took it apart and tested continuity, looks like I broke one of the 60amp fuses on the fuse chain link. Happy I found issue, hopefully nothing else is damaged.
Now replacing it, is there a specific part # for this whole group of fuses? Or should I just MacGyver a solder connection?
Also on a side topic, I still need to get the gas out, what is the correct way to bypass the fuel pump relay... should I apply 12v to the fuel pump connection pin below the rear seat? The tank is full, and I can't open the fuel pump panel or gas will spill out into backseat.
Again much appreciate!
Now replacing it, is there a specific part # for this whole group of fuses? Or should I just MacGyver a solder connection?
Also on a side topic, I still need to get the gas out, what is the correct way to bypass the fuel pump relay... should I apply 12v to the fuel pump connection pin below the rear seat? The tank is full, and I can't open the fuel pump panel or gas will spill out into backseat.
Mercedes does not sell separate parts. The whole pre-fuse block is $500+ at a dealer. FCP Euro, Auto Zone, etc sell separate fuses for $10 or so. MacGyver probably rules here.
Just snip out the parts of the blown fuse. Then go online and look for a 60 amp quick blow fuse. DO NOT USE A SLOW BLOW OR TYPE “T” FUSE. I think 60 A type ANL or similar will work, but check the physical size. The fuse can be clamped under the same output lug. On the input side, as long as it’s under the feed strip and near a lug, it doesn’t need to be soldered, although you can for peace of mind.
As far as emptying the tank: just wondering why you wouldn’t run a manual syphon pump from a discount store down the filler tube. I’m not a fan of gasoline in an open container and a possible spark, especially in an enclosed space like a garage.
Car is alive again and running well! I wasn't able to siphon the gas out of the fill hole - used my fluid extractor pump with a 3' plastic tube and it wasn't long enough to siphon the gas. So I connected the fuel pump under the rear passenger backseat straight to the battery and pumped the gas out through the fuel rail. Was able to get the passenger side empty this way - but the driver side still had fuel, which required me to open the cover and pump it out manually. I had to get all the gas out in my situation, so I went to extreme measures. Filled the car up with fresh gas, and after a few start cycles priming the fuel system, the car started up and has been running great. It's been 3 days running well, so decided to put some load on her and take the jet skis out for the day. All is well again =)
Much appreciation to the members pointing me to the pre-fuse block that I was unaware existed! Thank you!
Inside Pre-fuse block with replacement 60amp midi fuse:
Not your Lunar Blue MB from way back, right ? Congrats on your fix..I have found ny 09 C300 to be quite break down free over the years------LCD screen burnt out and TPMS module died (hardest part was finding where it was located). Other than that, smooth sailing (80K+ miles so far).
Owned this car for the past 10 years, it's been absolutely great. I have 135K miles on it now, and during that time I've had minor issues. I've had to replace the ESL steering wheel lock module due to motor failure ($10 fix) & the alternator due to a noisy bearing & the fuel filter assembly due to leaky plastic. This has happened in the past 2 years. I did replace motor & trans mounts & tie bar end links but I consider that regular maintenance items. Car is absolute blast to drive with the 6 speed. I unfortunately need to buy a tow vehicle and will be selling it soon =/
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
