EPC and Coolant warning lights with hidden 10a fuse...

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The Guv

New Member
Joined
Apr 18, 2015
Messages
11
Location
Scotland
Car
Mercedes ML 270 CDI
I wonder if anyone can help, I've recently acquired a 2001 ML 270 CDI and in my first month of ownership I've had the EPC and Coolant warning light come on, limp mode activated and the hidden 10a fuse blown (although mine was actually a 7.5a?). Also all of the screws had already been removed so I suspect this was an issue in its history too.

I replaced the fuse, the fan kicked in at full speed and I drove without the warnings for a few meters before the fuse blew again and the warnings came back with the limp mode activated! The fan stopped too... Great...

So as I didn't have another spare 7.5a fuse, put a 10a one in and shortly after that blew too. Put a 20a one in and it didn't blow (my last spare fuse!) but smoke started to appear from the engine bay and an electrical burning smell.. Then there was a clicking noise and the fan stopped. I pulled the fuse (which hadn't blown) and let everything cool down checking nothing was alight!

All was well and I ended up limping the car back on the motorway at a snails pace keeping an eye on the coolant temp (which didn't raise above middle point anyway!).

I've since got replacement 7.5a and 10a fuses, but when I fit them they don't blow and the warning lights wont clear, the car remains in limp and the fan doesn't operate at all.

I thought the fan was probably burnt out so replaced the complete unit including the resistor pack (or I think it's called a FCU?). But the same problem persists.

Is there something else can could have been burning and potentially blown? Or is there another fuse/relay that could have blown?

I can't see any melted loom and all the wiring to the fan is heavy duty so I can't imagine it was that.

Thanks in advance!
 
Well the burning smell was probably some wiring. Mercedes don't put thicker wire than needed (cost, weight) and really the fuse is there to protect the wiring when the consumer breaks (or the wire gets shorted to earth)

You need to follow the wiring and check it is all OK

Richard
 
Wiring appears to be fine. It's pretty thick wire too. Could the m55 burn out?
 
EPC light is normally related to fuel pressure... Have you had the car scanned?
 
Nah don't think it's that. Plus that wouldn't cause the fuse to pop. Drove perfectly before and replaced the fuel filter since too.
 
Nah don't think it's that. Plus that wouldn't cause the fuse to pop. Drove perfectly before and replaced the fuel filter since too.

I hear what you are saying... Maybe one of the fuel pump sensors has gone crazy? I'd look at the fuel temp sensor maybe?

Strange situation you have there though... Sorry I cant help more!
 
Saying that I have seen before that a faulty throttle peddle can cause the EPC light to come on... The faulty peddle would cause a severe lack of acceleration something similar to limp mode.
 
Power was fully restored after the fuse was replaced though, albeit for a short period of time.
 
Is there a relay for the engine fan? Maybe that's blown.
 

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