Adam Fischer

Thanks in advance for reading my looong description. It's an electrical issue so lots of details!

On my '04 E55 fuse #64 on the fuse block in the engine compartment popped last week and I am having trouble tracking down the reason. It appears a lot of things are on this fuse including the rotary light switch, the gauge cluster, the AC, and the front cigarette lighter. The car also doesn't run at full capacity when the fuse is blown. Kind of like the difference between sport and comfort mode. So it seems like a lot of possible culprits. If I replace it and start the car it will only go a few minutes before blowing again.

I have a stereo amp control knob in place of the front cigarette lighter so that has been removed for a long time. I still took the ashtray out and checked the wires for obvious signs of problems. Everything looked fine.

I also removed the entire light switch assembly and it was fine for about 30 minutes of driving but then the fuse popped again. It lasted longer than before but still blew.

Every time I've replaced the fuse and tested it I turned off the AC to try narrow down the cause. So I'm thinking maybe that's not it but who knows.

Tonight I had the car in the driveway with the key in position 1 and a new fuse installed. An hour later and it was still good. As soon as I turned the key to position 2 and all other electrical items powered up it popped.

I haven't found any posts about this fuse so I can't track it down to a common problem.

I don't know if this is important but just before it blew the first time I got the low voltage warning. I changed the voltage regulator. That was after it blew the first time so nothing I did with the alternator caused the fuse to blow but it might be a clue for someone smarter than me?!

Thanks for any input!

benznewcomer

you got any after market items hooked to that fuse? i had HIDs hooked up to one of the fuses and it cause it to blow

Adam Fischer

Thanks for the reply!

I do have some aftermarket stuff but I don't think it's on that fuse. Plus, the previous owner installed all the mods so they have been in there for a while.

Dublinoh

First understand I'm only guessing here...if the performance degrades when this fuse blows it could be parasitic drag from ac compressor if it is not turning freely and ac is on that fuse. I know you said it was off but....Also there is a pump for the cooling of the supercharger and I understand when it is not functioning the performance is dialed back...could it be on that fuse and failing? Are you confident that where you removed the cig lighter there is no chance of a short there? Smarter folks will follow....

Adam Fischer

Thanks for the insight Dublinoh. I'm pretty confident in the cig lighter because I checked the wires as far back as I could see and I went ahead and covered the wires and connector in electrical tape just to make sure nothing was getting in there. I don't know though, I can't rule anything out.

I might have to bite the bullet and let a dealer or experienced MB shop look at it since there are so many things attached to that fuse.

benznewcomer

keep in mind that my vehicle with the aftermarket lights was working fine for 18 months then all of a sudden it started giving me problems so it can happen at any time

Adam Fischer

Would it also burn out your lights when the fuse popped? All my bulbs are still intact but maybe I should pull them and see what the fuse does?

Adam Fischer

After pulling more items from the dash it seems like the climate control unite might be the problem. After removing it the fuse didn't pop for several miles. I replaced the unit and as soon as I turned the key the fuse went out.

On a side note, the perfomance problems don't seem to be fuse related. While searching for shorts I opened up the panel by the passenger footwell where the TCU is. There was oil on the TCU cable and I learned about the common problem these cars have with the connector on the transmission leaking and oil going up the wires. I replaced the connector, cleaned it up and cleared the code. Performance seems normal now.

While speaking to a local independent German car mechanic he said the CCU was chassis coded but I can't find any other info like that anywhere. I also see several of them on eBay. Going to do more research to see if that's true or if I can buy a new one and go from there. He suggested it could be something else like the SAM or other components in the same pipeline as the AC controls, so I don't know if I've completely solved the problem but I've certainly made progress!

Jarrod Mason

RileyC

Sorry to bump an old thread, did you find out the issue. I have the exact same symptoms.

Murdo

Not sure if this question has been asked and answered already. I have replaced the fuse for the cup warmer / cooler in my wife's GLE 400 but it pops as soon as I start the car. What is the next step in resolving this problem?

Any and all advise would be appreciated..

bbirdwell

Unplug the cup warmer/cooler. If the fuse does not pop then you need to replace the cup warmer/cooler. If it still pops you're going to have to trace the wire out to see where it is pinched or the insulation is abraded.

jordanabbott

Adam, did you ever work this out? I have the same issue and I’m at a bit of a loss!