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.
That's my feeling...the one prior poster pried up without releasing tabs and broke the base where the tabs engaged. The replacement profuse fit back in fairly snug luckily.
The pyrofuse in this post had "blown" because of an impact I presume (not my original post) which disconnects battery power. The pyrofuse normally has 3 ohms of resistance across the sensor lead terminal, 0 when blown, so resistor tells ECU system intact. I also have heard this resistor insert is used when the squib from an airbag has blown 2nd accident, it will fool the pyrofuse into sensing a functioning airbag which I suspect was the reason for the resistor add on here.
The pyrofuse in this post had "blown" because of an impact I presume (not my original post) which disconnects battery power. The pyrofuse normally has 3 ohms of resistance across the sensor lead terminal, 0 when blown, so resistor tells ECU system intact. I also have heard this resistor insert is used when the squib from an airbag has blown 2nd accident, it will fool the pyrofuse into sensing a functioning airbag which I suspect was the reason for the resistor add on here.
Is this a work around for a blown pyro fuse? i just picked up a 2012 c300 that had some very minor accidents yet passenger headrest is the only deployed item in interior no airbags deployed, the car will not crank at all but radio engine fans lights everything works i can put it in drive and shift but the car will not crank at all any suggestions, thank you.
You pull up the top cap on the pyro to release it, easy as
The resister is to fool the computer to say the fuse is not blown.
It will not fix a blown fuse.
The Mercs have many high current fuses hidden in modules, in the ML I had a blown fuse in the module under the drivers floor. This gave an indication of a blown PYRO and all sorts of funny things like airbag faults no start etc.
I had to physically track the battery cables to find.
The fuses can be replaced, I think i have a post on it somewhere
I had a pyro error after all that and it was actually because the plug was seating. You have to pull the cap up, put plug in and push cap down. It actuates the plastic tabs people mention here that work like a clamp to connect. Do not try and mess with those little things the plugs are near impossible to find.
Last edited by Terry WM; Sep 14, 2024 at 08:57 PM.
Is this a work around for a blown pyro fuse? i just picked up a 2012 c300 that had some very minor accidents yet passenger headrest is the only deployed item in interior no airbags deployed, the car will not crank at all but radio engine fans lights everything works i can put it in drive and shift but the car will not crank at all any suggestions, thank you.
Yes, it is. Replacement pyro fuses can be bought on eBay. I don’t recommend the resistor work around. The pyro fuse is there to shut off the engine and the fuel pump in an accident or a rollover to lessen the chance of fires from fuel spills. Search this forum for additional threads on pre-fuse boxes. There are a number of pre-fuse box models and each has a specific pyro fuse, so you will need to see it to get the right one. You can test it for continuity to make sure that’s your problem.
If there is an issue with it then best to replace it. Instructions are pretty straight forward. Can always buy a used one since new dont appear to be available. Can even buy a used F32 and remove the one in it, just make sure its still in there.
Hopefully they have it or there is a different part #.
I was curious how much a replacement costs so looked up my parts diagrams for the part# and all the Mercedes branded websites say its unavailable. Just looked again and ESC seems to have it though. I found a few on ebay though they had different part #'s but all started with 204*******. They look the same.
I didnt look in my car so who knows what part# is in there. Its why I didnt bother posting part #'s above since I didnt want to confuse anyone and its best to look in the car for the exact part#.
Does anyone know how to open this F32 prefuse box or have the procedure? I know there are tabs to release it but I was having trouble getting them to release.
Thank you Tim - but I was talking about how to open the box completely to replace the pyro fuse. I got it though. This is from a G550, the F32/3 pre fuse box.
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.
