My Water Pump Fuse is blowing up instantly.

[Loose 0]

Hi all,

I've got a BMW 335i 2008 with 81km, Sedan, stage 2 tune and mods.

Recently I've had a problem with my water pump not working and ends up over heating the car. With some research and looking at forums other BMW owners had the same problem, where car would over heat and big radiator fan would kick in. So I ended up changing the water pump and thermostat to a new one. Topped up with coolant and tried to do the blend process but water pump does not seem to come on. Also saw that someone had the same problem as me where he had new water pump and thermostat but water pump would not turn on, he ended up changing the fuse in the ECU box and it fixed his issue. I ended up opening the ECU box and finding out that the fuse has blown. So I rush down to the shop and grab a new fuse (exactly the same fuse) put it inside the same spot as before and instantly it blow. I've called my friend and told him the same story and he determined that its a short circuit somewhere in the wiring of the system something along the lines of some wire not being grounded that causes the problem. 

 

My question is does anyone know what many be causing this issue? and how would I fix this?

 

Any help would be much appreciated and welcomed as I've been trying to fix this for quite something now and completely lost.

 

Thanks 

Edited August 11, 2019 by Loose

[M3AN 4015]

It's almost certainly a short circuit and the blown fuse is likely the cause of your original pump not working (the original pump may be fine).

If you're not familiar with tracing electrical gremlins you may need to take it to an auto electrician. If you have a multimeter and know how to use it then you can just get stuck in.

A visual inspection including tracing all the wires is a good place to start either way. Look at all of the (relevant) wires and connectors between the pump and fuse, you're looking for any wear, loose wire, touching wire, loose connectors etc. If you disconnect the electrical connector to the pump, replace the fuse and start the car does the fuse blow again (without the pump connected)? If so then you have a short - somewhere a wire will be exposed and connecting to something else.

 

[Loose 0]

1 hour ago, M3AN said:

It's almost certainly a short circuit and the blown fuse is likely the cause of your original pump not working (the original pump may be fine).

If you're not familiar with tracing electrical gremlins you may need to take it to an auto electrician. If you have a multimeter and know how to use it then you can just get stuck in.

A visual inspection including tracing all the wires is a good place to start either way. Look at all of the (relevant) wires and connectors between the pump and fuse, you're looking for any wear, loose wire, touching wire, loose connectors etc. If you disconnect the electrical connector to the pump, replace the fuse and start the car does the fuse blow again (without the pump connected)? If so then you have a short - somewhere a wire will be exposed and connecting to something else.

 

Hi 

I've just seen that some coolant has leaked into the inside of the power adaptor that connects to the water pump, this many have caused the issue. I've taken the water pump out and currently cleaning the coolant off the wire and the 4 pin connector of the water pump. 

Will try to put in a new fuse while the power wire is out of the water pump and see if it still instantly blows up the fuse.  

Thanks for the help, will keep you updated.  

[M3AN 4015]

Good find, sounds like it could well be the cause. Good luck.

 

[Loose 0]

Looks like it's not the wire. Put in a new fuse and tried it without the water power wire connected and it did not blow up. Then I tried with water pump power connected and blow it up instantly. Probably cause its not a OEM water pump. I'm just going to have it fixed by euro surgeon tomorrow. 

 

   

[n54build 0]

so I'm having this same issue.. my car has a 40amp fuse and popped... I put a new one in and drove probably 6+ miles and car got hot yet again  I pull over and the fuse was popped.  help please.  

[smiddy 76]

A 40 amp fuse is like welding wire!

A fire at that amp load is very possible.

Most likely a motor short in pump, would suggest a auto electrical trace of circuit by a specialist, to much can go wrong here!

 

[jon dee 500]

Good advice ^^^^ there !!! Fuses are there to provide over-current protection for the connected circuit. They do not blow unless there is some kind of fault condition, and before replacing the fuse the fault that caused the fuse to blow should be located and rectified. Never replace a blown fuse with one having a higher rating to try and "cure" the fault... that is a recipe for disaster.

In the case of a dead short to ground the battery can easily deliver >200 amps into a circuit designed for 20 amps and that will instantly result in the smell of burning money... unless a fuse pops to interrupt the current flow. Fortunately, most cars have several fuses of different ratings in the current path to electrical components on a car, and the lowest rated fuse should blow first before the current gets high enough to do any damage. But if you accidentally short out an alternator or starter motor you can get some pretty good Guy Fawkes sparkler action

Cheers...

[EELLI1120 0]

Did this ever get resolved going thro the same issue as we speak