McLane

Problem:

My e320 keep blowing the 20 amp fuse in the K40 when I turn the key to the "ignition" position. The car will not crank at all. This also precludes me from being able to link the OBDII scanner to the computer to look for codes.

What I have done already:

1. Jumped the pins on the starter relay. The car will crank, but not start because of the 20 amp fuse blowing when I turn on the ignition.

2. Replaced the K40. I swapped the K40 from a wrecked car and the same 20 amp fuse blows.

3. Charged the battery.

So...does anyone know what the 20 amp fuse goes to in a 1998 E320 4matic wagon?

Plutoe

I believe that 20A fuse is in the fuel pump relay(K27) circuit. Good Luck

McLane

Thanks for the suggestion. How should I proceed? Unhook the fuel pump and see if it still blows the fuse? Thanks for your time.

Plutoe

I guess that if you don't have any simple diagnostic equipment---give it a try, just remember that the relay is the switch that turns the pump on or off. Good Luck

JOHN GILL

I had a similar problem with my 2002 E240 ( V6 ) .Turned out to be the fan which cools the ECU had seized and when the Ign was switched on it blew the 20A fuse .The solution was to remove the two pin plug which takes the leads direct to the fan ( its in the same area as the fuse on LHS looking in from the front bumper ) .Car now works normally and since we rarely have extremely high Temperatures here in the UK I can replace / repair the fan later.
Not sure if this helps but might be worth a try .
Is the fuel pump on the same cct ?

Plutoe

I think you made a very BIG mistake by not replacing the module fan. That choice will have expensive consequences if left unattended.

Most if not all laptops and desktop computors sold all over the world have ecu fans and are not disconnected because of the weather, but are connected because of the heat generated by the ecu. Happy Holidays

JOHN GILL

I was surprised at the toneof this reply - as a new user I had expected the MB Forum to be a place where fellow enthusiasts helped each other - as best they could ,In this case I may have not described the exact fan that is faulty - so i will quote from the W210 common faults section which describes it better than I did - "
· Open the bonnet, on the near side inner wing, there your find a black box, should have a air-con sticker on there, remove the lid, four Philips screws, there your find a couple of ECU,s a fuse board, right, there should be a coupe of red 10 amp fuses together, that’s the fault, a blown fuse! This fuse is one of the supply fuses for the ABS control and also the supply fuse to the ECU cooling fan, also in the black box you’re working in, this fan is what has caused the fuse to blow, they seize up!

Now this fan isn’t needed in this country!! What you have to do next is, follow the fuse board to the engine side, there you will find a pair of small twisted wires coming from a the fuse box ( 2 pin blue plug ), un-plug it, replace the blown fuse and fault now fixed!! Cost of job, a 10 amp fuse!! "
Also users of the forum should surely not make assumptions about others expertise and knowledge - in this case the contributor assumed I did not know about ECUs and heat generation - wrong - as someone who started working on computers back in 1981 - servicing all Alan Sugars Amstrads then moving on through a succession of technical posts tospending the last 15 years as a director of panasonic europe ,I am well aware of the technicalities of solid state circuitry .
So , lets stay focussed on trying to help each other - if something seems wrong , then query it first ,before making ill-considered statements ?
John
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Hirnbeiss

Don't get bent out of shape by Plutö; he has a long history of helpful impoliteness.

Plutoe

My point was that someone with way more electronic engineering experience that me designed in a module cooling fan on a car that would be sold worldwide.

There must have been a very good reason for the addition. However you are very correct we all have choices and if you did like my tone I apologies. But to just arbitrary say your local weather conditions do not warrant fixing the fan does not make sense to me, and even more know that I know you flogged computers.

RC46

Man if you thought his reply was condescending or degrading, STAY OFF the racing forums, you will be brought to tears by some respondents. Just sayin