[Nesquik15]

Hello folks, what a pleasure to finally own my first bmw its a 2008 335xi, and first problem as soon as I got the car: overheating issue, motor runs excellent, however when the operating temp is reached the pump will not operate, already replaced pump and thermostat, got one fault stored in DME: 2e84 no communication with the water pump, what are the common fixes? Can anyone describe operation of the fuse block on top of the battery since I heard its related to the water pump, Help me get back on the road! thanks!

[nightops]

i'm guessing your out of warranty- thats kind of major hope you dont drive it while its overheating. did you check the fuse for the water pump (assuming there is one). could there possibly be an electrical connection to the water pump that isnt connected all the way or improperly? also is the thermostat working ok? if that fails it may be worth it to bring it to an independent or dealer for diagnostic, electronics on this car are intimidating to say the least
...gl

[N54_Fan]

Originally Posted by Nequik15

Hello folks, what a pleasure to finally own my first bmw its a 2008 335xi, and first problem as soon as I got the car: overheating issue, motor runs excellent, however when the operating temp is reached the pump will not operate, already replaced pump and thermostat, got one fault stored in DME: 2e84 no communication with the water pump, what are the common fixes? Can anyone describe operation of the fuse block on top of the battery since I heard its related to the water pump, Help me get back on the road! thanks!

Could you have left the temp sensor on the water pump off? If so there woould be "no communication" There is a plug that is attached to the WP that needs to be plugged in well. Also the ground for the WP is just in front an dto the driver side of the pump. If it is loose or disconnected it too would result in "no communication".

[cn555ic]

I would say the connection wires for the t state is not plugged.

[Nesquik15]

Originally Posted by N54_Fan

Could you have left the temp sensor on the water pump off? If so there woould be "no communication" There is a plug that is attached to the WP that needs to be plugged in well. Also the ground for the WP is just in front an dto the driver side of the pump. If it is loose or disconnected it too would result in "no communication".

Temp sensor? I believe there is only one four pin connector to the pump that is plugged in. The ground is the wire that is towards the front of vehicle near the pump? it seemed tight

[Nesquik15]

Originally Posted by nightops

i'm guessing your out of warranty- thats kind of major hope you dont drive it while its overheating. did you check the fuse for the water pump (assuming there is one). could there possibly be an electrical connection to the water pump that isnt connected all the way or improperly? also is the thermostat working ok? if that fails it may be worth it to bring it to an independent or dealer for diagnostic, electronics on this car are intimidating to say the least
...gl

Yep the 50Amp fuse in the DME box is there and is good

[N54_Fan]

Here is a copy of the Cooling System Electrical connections from the Bentley manual. See if this helps you. I would check continuity of these connections.

[Nesquik15]

thanks for the schematic!

[Nesquik15]

Will try to do the pin out test tmrw, going to post results

[nikitino25]

How do you check the coolant temp and or know it's overheating?

[enrita]

Originally Posted by nikitino25

How do you check the coolant temp and or know it's overheating?

With Inpa, performance wheel, bt cable or the hidden menu. when overheating you get a light and reduce power .

[import36]

hey Nequick...got your pm. i would definitely check the continuity as mentioned above....make sure the pump is actually getting power down there. i had issues twice...first time i needed the thermo and pump replaced. the second time....the problem ended up being a faulty power distribution block(on top of the batter in the back). it caused an inline fuse to blow which cut power to the pump. unfortunately i don't have any more detail than that...

[JamesM3M5]

Also check the ground wire from the pump to the front timing case cover. There is a short ground wire that terminates to a ring terminal on the front of the engine block.

The power for the water pump comes right from the top of the battery junction block as stated above. Check all the battery junction block connections. Some are snap-in, some are 13mm nuts.

My thermostat connection (MAP Cooling) wires have been hitting the subframe during hard acceleration. I had to de-pin the connector and put moisture seal heat shrink around it to protect them from hitting the subframe. It looks like the orange power wire (0.5mm) from the Junction Box (fuse 78 or 37 depending on your build date) powers the electronics in the water pump AND the MAP cooling in the thermostat. If that wire shorted to the subframe, it will pop the fuse.

[Nesquik15]

Originally Posted by JamesM3M5

Also check the ground wire from the pump to the front timing case cover. There is a short ground wire that terminates to a ring terminal on the front of the engine block.

The power for the water pump comes right from the top of the battery junction block as stated above. Check all the battery junction block connections. Some are snap-in, some are 13mm nuts.

My thermostat connection (MAP Cooling) wires have been hitting the subframe during hard acceleration. I had to de-pin the connector and put moisture seal heat shrink around it to protect them from hitting the subframe. It looks like the orange power wire (0.5mm) from the Junction Box (fuse 78 or 37 depending on your build date) powers the electronics in the water pump AND the MAP cooling in the thermostat. If that wire shorted to the subframe, it will pop the fuse.

Great info!
Where is that 78 or 33 fuse located?

[JamesM3M5]

What is your build date?

[Nesquik15]

Originally Posted by JamesM3M5

What is your build date?

It's 10/07

[JamesM3M5]

Fuse 37 in the Junction Box. It will be behind the glove box. You don't have to remove the glove box, just empty it and remove the black divider at the back of the box. There will be a small card you can unfold and find the position of fuse 37.

If the fuse is OK, you may have a bad wire or some other problem between the pump and the DME harness. The DME communicates to the pump with a short digital signal to tell the pump how fast to run. With just power to the pump, it will run at a default slow speed. The DME signal then tells the module in the pump how fast it needs to run. There may be a fault on that line, a bad connector, or something else causing the communication to fail.

[Nesquik15]

Originally Posted by JamesM3M5

Fuse 37 in the Junction Box. It will be behind the glove box. You don't have to remove the glove box, just empty it and remove the black divider at the back of the box. There will be a small card you can unfold and find the position of fuse 37.

If the fuse is OK, you may have a bad wire or some other problem between the pump and the DME harness. The DME communicates to the pump with a short digital signal to tell the pump how fast to run. With just power to the pump, it will run at a default slow speed. The DME signal then tells the module in the pump how fast it needs to run. There may be a fault on that line, a bad connector, or something else causing the communication to fail.

Hey thanks for the great help M3m5 will check power at the connector and report with findings !

[Nesquik15]

Alright, so looks like I was able to isolate the problem found no power at the f07 fuse proceeded with checking power from battery, found power at the wire from battery fuse block to the wire running to under hood, however no power found at the under hood, thus faulty wiring under the car, going to stealer tommorrow.

[JamesM3M5]

If you've gone this far, why take it to the most expensive repair shop on the planet? A good independent shop should do a good job repairing the wiring harness for a lot less. The dealer may say you need a new wiring harness - no repairs. They're weird like that.

[Nesquik15]

Well James come to find out the fuse on top of the battery was partially melted, so I used another free slot to plug in the connector and all is ok now!