Electric aux engine fan

[Sajk]

Hi Guys,

Bit of a brain teaser here. I am not sure if its a problem or not. The aux electric fan in front of the radiator comes on when I hit the air con button but testing it with INPA gets no result. I.E it does not start. All the other tests (vanos, air pump etc) in INPA seem to work except for this one.

So I am not sure what is wrong. Perhaps INPA cant activate the fan or there is some other electrical issue I need to chase down.

Vehicle is a 1998 09 build so it came with M52TU and MS42 DME. Relevant bit of the VIN if anyone feels like looking it up on realoem is LE91070.

Vehicle code is Z3 E36 BMW Z3 2.8. Type Code: CH32

This seems like it is a problem to me and I would welcome some advice.

thanks

[Blacklane]

The electric aux fan is controlled using several relays, not through the DME. There is a two-level temp sensor on the side of the radiator set at 91 and 99 degrees C. Then there is a relay that energizes the fan at low speed for A/C or 91 degrees C radiator temp. There is another relay that energizes the fan at high speed for 99 degrees C radiator temp.

Note that the radiator temperature control is independent of the engine temperature control.

[Sajk]

Is it correct that on the M52tu with ms42 this is still not controlled by the DME? This package is pretty much what went into the E46 328 as far as I know. At any rate your comments worry me. The clutch on the mechanical fan seems to disengage at about 93c. I monitored the coolant temp with the torque app and watched it drop from 96 to 93 with only the clutch fan engaged.

Air con off and at no time did the electric fan start. Also the Z3 electrical diagnostics manual states that at startup the DME triggers the fan for a brief period and then measures the voltage it generates after the power is turned off and it spins down acting as a generator. In this way it is supposed to be able to set a code about the fan.

Information on this seems to be varied and i know if it goes to the dealer it will just cost money. See below from the MS42 manual I have.

ELECTRIC FAN
The electric cooling fan is controlled by the ECM. The ECM uses a remote power output
final stage (mounted on the fan housing)
The power output stage receives power from a 50 amp fuse (located in glove box above
the fuse bracket). The electric fan is controlled by a pulse width modulated signal from the
ECM.
The fan is activated based on the ECM calculation (sensing ratio) of:
• Coolant outlet temperature
• Calculated (by the ECM) catalyst temperature
• Vehicle speed
• Battery voltage
• Air Conditioning pressure (calculated by IHKA
and sent via the K-Bus to the ECM)
Activation of the electric fan:
When the vehicle is first started the fan is activated briefly (20% of maximum speed), then
it is switched off. This procedure is performed for diagnostic purposes.
The voltage generated by the fan when it slows down (it becomes a generator at this time)
must meet the power output stages programmed criteria. This will confirm the RPM of the
fan, if this is not met the signal wire from the output stage is switched to ground and a fault
is set in memory.
NOTE: If the ECM indicates a fault check the fan for freedom of movement

[328 Power 04]

E46/e39 is controlled by dme. Z3 (E36) got simple relay/temperature controlled fan. So you cannot activate with INPA on Z3.

[BimmerBreaker]

And as such it wont cycle on at startup

If it comes on with A/C switch and car is otherwise not overheating then I would assume its fine

[Remotion]

It is purely for AC, not for anything else. It should never otherwise activate.

[BimmerBreaker]

It is purely for AC, not for anything else. It should never otherwise activate.

The fan switch in the radiator switches on the aux fan when the coolant reaches a certain temperature. The aux fan absolutely should activate independent of A/C depending on the circumstances. In some climates, under some driving circumstances, it could be so that the aux fan does not need to come on - but saying it should "never otherwise activate" is false.

The aux fan cooling the car is the only thing keeping the thousands of mechanical fan deleted E36's and Z3's out there from overheating

[danomite]

The electric aux fan is controlled using several relays, not through the DME. There is a two-level temp sensor on the side of the radiator set at 91 and 99 degrees C. Then there is a relay that energizes the fan at low speed for A/C or 91 degrees C radiator temp. There is another relay that energizes the fan at high speed for 99 degrees C radiator temp.

Note that the radiator temperature sensor is independent of the engine temperature sensor.

Fixed!

And as such it wont cycle on at startup

If it comes on with A/C switch and car is otherwise not overheating then I would assume its fine

^^^ This!

It is purely for AC, not for anything else. It should never otherwise activate.

Incorrect!!! The aux fan serves 2 functions: 1) To keep the AC condensor cool, allowing the AC to blow continuous cool air. 2) To keep the car from overheating once the coolant in the radiator becomes too hot.

The fan switch in the radiator switches on the aux fan when the coolant reaches a certain temperature. The aux fan absolutely should activate independent of A/C depending on the circumstances. In some climates, under some driving circumstances, it could be so that the aux fan does not need to come on - but saying it should "never otherwise activate" is false.

The aux fan cooling the car is the only thing keeping the thousands of mechanical fan deleted E36's and Z3's out there from overheating

...mostly true. Spirited forward motion and cool ambient temps will also keep the fan-deleted cars safe.

[deni2s]

Worth mentioning, that you need to check the wiring near radiator temp switch - make sure the brown wire is in the middle. There are some cars with incorrect wiring from factory.

[Blacklane]

"Note that the radiator temperature sensor is independent of the engine temperature sensor.
...Fixed."

Thanks, but I meant what I wrote:

"Note that the radiator temperature control is independent of the engine temperature control."

The temperature of the coolant in the radiator is controlled by a closed loop system involving the 2-stage temperature sensor on the radiator and the 2-speed fan. The temperature of the coolant in the engine is controlled by the mechanical thermostat, which allows more and less hot water to leave the engine. These two temperature control systems operate independently.

Additionally, there is a coolant temperature sensor on the block that informs the engine computer (DME) so it can optimize the engine performance.

[me77]

On my car, INPA fan control does not work and cooling water/radiator outlet temp always shows some really low value. It also shows a shadow code for that sensor, no code for the fan though. But as far as I know, a Z3 only has the sensor in the cylinder head (for the DME & gauge cluster) and a simple on-off switch in the radiator on the passenger side for the aux fan. There is no radiator outlet temperature sensor on the Z3. My car is a M52TU with the MS42, made 12/1998.

[328 Power 04]

The m52tu uses MS42 dme.

There is no radiator outlet temp sensor on Z3 so it reads open circuit, and the shadow code is actually a disabled code. INPA can see disabled codes, for BMW engineering purposes. On Z3 the fan is not DME controlled. The Z3 dme flash has the aux e-fan disabled.

[me77]

You're right, that was a typo. Corrected it, but good to know that someone knowledgeable confirms my findings.

[328 Power 04]

Yep. Once I had flashed an E39 with Z3 software, and the front e-fan didn't turn on at all, due to Z3 flash settings.
Which of course will start overheating the car while idling without any fans.
It was just a test, so no biggie.

[rf900rkw]

On my long list of to do stuff is to retro an E46 fan control into my wife's coupe.



Seems to me someone here bought a flashed DME (EWS delete?) That had the fan control turned on , setting temp sensor codes.

[Sajk]

OK so even if I have it turned on in the tune all it will do is set a code because the radiator outlet temp sensor is not there?

How do the guys who do the fan delete manage if the aux fan does not run?

PS. Is there more than one thermostat for these things? Mine was stuck open and beside taking a while to warm up it ran well and the fan clutch almost never locked up. Now it does it very often.

[BimmerBreaker]

How do the guys who do the fan delete manage if the aux fan does not run?

PS. Is there more than one thermostat for these things? Mine was stuck open and beside taking a while to warm up it ran well and the fan clutch almost never locked up. Now it does it very often.

We either keep moving or overheat with no aux fan...

Just one thermostat. If it was stuck open it wouldnt get hot enough to engage the fan, that sounds normal.

[Mark Bielick]

With the fan delete, if you have no auxiliary fan, and are not moving, you will overheat. 100% guaranteed. That being said, as others have mentioned, how much redundancy do you need in the system? I chose to add the Spal electric fan because I experienced the pusher fan not operating while stuck in traffic, and I did not want to every experience it again. Others choose to rely on the pusher fan operating. To each his own...