DME Fault 35 - Electronic Fan (Relay) - Auxiliary Fan Relay Not Working - The Unofficial BMW M5 Messageboard (m5board.com)

SleeperE39 · 25th April 2009, 08:45

While stuck in stop/go traffic I noticed my coolant temp guage get very close to the red zone. Normally the coolant and oil temps are around the 50% mark.

I quickly put the heater on full tilt and this brought the temps down to normal.

I'm OK as long as I don't sit idling too long.
Apparently the main fan on the engine isn't sufficient to meet the cooling demands while stationary.

Tried putting on the AC - no fan.
Suspected something wrong - hooked up the scan tool (autoengenuity)

Have a DME error
Error 35 - Electronic Fan (Relay)
Fault Frequency 130

Car is a US LH Drive Build 05-2001
What happens is the fan is supposed to come on when the coolant temperature exceeds a certain threshold.
It should also come on with the AC compressor.

From the WDS

Electric FanElectric Fan

Vehicles with M62TU, S62 and M73 engines feature a viscous fan as well as an electric fan. The electric fan cuts in when the cooling capacity of the viscous fan is no longer sufficient.
The electric fan is activated by means of a power output stage directly on the fan motor. The motor control module activates this power output stage by means of a square-wave signal with duty factors (variable pulse width) between 10 % and 90 % thus controlling the various speeds of the electric fan. Pulse duty factors less than 5 % and greater than 95 % do not trigger activation but rather they are used for fault detection purposes. The power output stage features its own positive and ground supply.
The fan speed is influenced by the coolant temperature at the radiator outlet and the pressure in the air conditioning system. The fan speed is reduced as the vehicle speed increases.
If a fault occurs during operation a corresponding fault code will be stored in the fault code memory of the DME control module.
For the purpose of checking operation and troubleshooting, the diagnostic program offers the option of activating the electric fan directly via the DIS tester/MoDiC.

I tried to force it on with my scan tool, but the fan doesn't come on.
Checked the connector to the fan - looks ok.
I get 12V between Pins 4+, and 1 Chassis.

WDS version 12 isn't any help
The TIS is a nightmare to navigate.

From what I can tell - the WDS claims that the fan speed is controlled by a PWM signal right from the DME.
This would make sense as there is always battery voltage going to the fan. Pin 2 is the PWM signal from the DME.

I put a scope on the PWM signal and activated the different fan speeds from the scan tool. The signal is changing, and the duty cycle is correct - 30% fan speed - 70% duty cycle, 90% fan speed 10% duty cycle.

Here are my measurements on Pin 2 - PWM signal.
Battery voltage about 12.3VDC
Off 8.36V, 94% positive PWM
30% 7.29V, 69.2% positive PWM
90% 1.6V, 9.4% positive PWM.

Fan does not spin on any setting.

Now - why does the DME report a fault 35 electronic fan (relay)
Is my scan tool reporting the fault wrong - meaning the (relay) wording?
I don't believe there is a relay as speed is controlled by a PWM signal.
Why doesn't the motor spin?
Time to replace the fan?

All I know is there is a PWM signal that looks good, there is battery voltage, and the fan spins freely - there are no obstructions.
Yet the fan doesn't work.

Nothing I can find in the WDS says anything about the auxiliary fan motor speed control.

Samsir · 25th April 2009, 09:36

Quote:

Originally Posted by SleeperE39

While stuck in stop/go traffic I noticed my coolant temp guage get very close to the red zone. Normally the coolant and oil temps are around the 50% mark.

I quickly put the heater on full tilt and this brought the temps down to normal.

I'm OK as long as I don't sit idling too long.
Apparently the main fan on the engine isn't sufficient to meet the cooling demands while stationary.

Tried putting on the AC - no fan.
Suspected something wrong - hooked up the scan tool (autoengenuity)

Have a DME error
Error 35 - Electronic Fan (Relay)
Fault Frequency 130

Car is a US LH Drive Build 05-2001
What happens is the fan is supposed to come on when the coolant temperature exceeds a certain threshold.
It should also come on with the AC compressor.

From the WDS

Electric Fan

Vehicles with M62TU, S62 and M73 engines feature a viscous fan as well as an electric fan. The electric fan cuts in when the cooling capacity of the viscous fan is no longer sufficient.
The electric fan is activated by means of a power output stage directly on the fan motor. The motor control module activates this power output stage by means of a square-wave signal with duty factors (variable pulse width) between 10 % and 90 % thus controlling the various speeds of the electric fan. Pulse duty factors less than 5 % and greater than 95 % do not trigger activation but rather they are used for fault detection purposes. The power output stage features its own positive and ground supply.
The fan speed is influenced by the coolant temperature at the radiator outlet and the pressure in the air conditioning system. The fan speed is reduced as the vehicle speed increases.
If a fault occurs during operation a corresponding fault code will be stored in the fault code memory of the DME control module.
For the purpose of checking operation and troubleshooting, the diagnostic program offers the option of activating the electric fan directly via the DIS tester/MoDiC.

I tried to force it on with my scan tool, but the fan doesn't come on.
Checked the connector to the fan - looks ok.
I get 12V between Pins 4+, and 1 Chassis.

WDS version 12 isn't any help
The TIS is a nightmare to navigate.

From what I can tell - the WDS claims that the fan speed is controlled by a PWM signal right from the DME.
This would make sense as there is always battery voltage going to the fan. Pin 2 is the PWM signal from the DME.

I put a scope on the PWM signal and activated the different fan speeds from the scan tool. The signal is changing, and the duty cycle is correct - 30% fan speed - 70% duty cycle, 90% fan speed 10% duty cycle.

Here are my measurements on Pin 2 - PWM signal.
Battery voltage about 12.3VDC
Off 8.36V, 94% positive PWM
30% 7.29V, 69.2% positive PWM
90% 1.6V, 9.4% positive PWM.

Fan does not spin on any setting.

Now - why does the DME report a fault 35 electronic fan (relay)
Is my scan tool reporting the fault wrong - meaning the (relay) wording?
I don't believe there is a relay as speed is controlled by a PWM signal.
Why doesn't the motor spin?
Time to replace the fan?

All I know is there is a PWM signal that looks good, there is battery voltage, and the fan spins freely - there are no obstructions.
Yet the fan doesn't work.

Nothing I can find in the WDS says anything about the auxiliary fan motor speed control.

Hi,

Had same problem, the fan did not spin.

There is a relay inside the fan as I know.
There is also a 50 amp fuse under your glove compartment, but if you have constant 12v on blue cable to the fan this fuse is ok.

My fuse was blown and after replacing it the fan started smoking. ( lets say I was quick to disconnect it again

)

I guess there is not much to do here but to change the fan.

Samsir

SleeperE39 · 25th April 2009, 17:18

Quote:

Originally Posted by Samsir

Hi,

Had same problem, the fan did not spin.

There is a relay inside the fan as I know.
There is also a 50 amp fuse under your glove compartment, but if you have constant 12v on blue cable to the fan this fuse is ok.

Samsir

Relay inside the fan?
WDS doesn't have any detail on this.
Wonder if the fan is repairable?

Checking RealOEM.

The new part is 64546921395 - is the replacement at $335.92 USD
Local dealer has it in stock for $455 CAD.
Looking now at salvage yards.

Supposedly the same part number for all E39's from 09/1998 onwards.
Doing a quick check with the ETK confirms this.

Strange that they all call for the same fan, as it appears as though many use a resistor pack with various relays to get normal, med, high speeds - whereas the M5 is continuously variable due to the PWM control.

One thing I find very frustrating about the car is the lack of well written and clear technical and service manuals.
I could help myself much faster if the information was there.
Sure the WDS, TIS, and the ETK are great resources online, but navigating these - especially the TIS is really a challenge for the layman.

There has to be some laying around.

Samsir · 26th April 2009, 22:00

Quote:

Originally Posted by SleeperE39

Relay inside the fan?
WDS doesn't have any detail on this.
Wonder if the fan is repairable?

Checking RealOEM.

The new part is 64546921395 - is the replacement at $335.92 USD
Local dealer has it in stock for $455 CAD.
Looking now at salvage yards.

Supposedly the same part number for all E39's from 09/1998 onwards.
Doing a quick check with the ETK confirms this.

Strange that they all call for the same fan, as it appears as though many use a resistor pack with various relays to get normal, med, high speeds - whereas the M5 is continuously variable due to the PWM control.

One thing I find very frustrating about the car is the lack of well written and clear technical and service manuals.
I could help myself much faster if the information was there.
Sure the WDS, TIS, and the ETK are great resources online, but navigating these - especially the TIS is really a challenge for the layman.

There has to be some laying around.

Hi,

There is no way around buying the complete unit, No.5 in "your'' (real oem) diagram.

You can buy all the other parts as you like, but not the fan motor.

(made me a little pissed off as there was no reason to change the plastic parts around, just more expensive)

Don't bother trying to fix it as I'm sure you will not get it running as a reliable part.

Anyway you should only need to change this once in the lifespan of an M5.

Cut off the black connector and the cables of the old one (for later use for anything else) and let it sail into the night.

Cheers
Samsir

s4kebomb · 28th April 2009, 21:08

There are cheaper ones on ebay and it works great BUT because of the different design on the fan fins, they are noisier than the OEM one.
It bothers me at first, but I got used to it.

The one on ebay was made by DEPO and they are $200 if I'm not wrong.

SleeperE39 · 29th April 2009, 00:47

s4kebomb - thanks for the tip. I went the ebay direction. Came to $200 with shipping to Canada via USPS. Placed the order today - item shipped already.
I'll post the results - ordered from an ebay online store freshcabinair.com - $159 + shipping.
Claim is the part is a replacement for BMW PN 64546921395

firebird400 · 26th June 2009, 19:43

How did that fan work out for you?

I have been getting code 35 for while now, although the car has no over heating problems. So from what I have read, I would need to replace the entire electric fan to get rid of the code?

SleeperE39 · 26th June 2009, 20:07

Quote:

Originally Posted by firebird400

How did that fan work out for you?

I have been getting code 35 for while now, although the car has no over heating problems. So from what I have read, I would need to replace the entire electric fan to get rid of the code?

Fan works great - turns out it wasn't required.
Problem was the +12V and DC common wires were burned badly

They were conducting JUST enough to get a reading on a multimeter - so that's how I diagnosed the FAN being bad (wrong!)

So the new fan - works fine - I have a used fan as a backup.

When I got the new fan installed I used my tool (autoengenuity) to trigger the DME to turn it on - nothing.

Checked the 50A fuse (buried behind the glovebox - OK)

Measured the connector at the fan again - no constant 12V. WTF?

Checked at the fuse - 12VDC - so there was a wire break somewhere.
I'll post pictures up here to see the condition of the wires.

50A in the size wire that is there is too much. Insulation was broken and cracked through most of the wiring harness. Had to replace about 6 ft of wire on both power and GND.

I see this as a total fire hazard. What were they thinking? 50A in a small wire - check wds for the wire size - it really should be larger.
I re-wired with 10awg from the connector to just about the air filter on the right side. IF I had more cable I would have brought it right to the 50A fuse.

SleeperE39 · 26th June 2009, 20:19

For your viewing pleasure
Auxiliary Electric Fan not working? Check the wiring.
The break was in the right side wheel well behind the splash guard.
If the fuse is good, then you may need to replace the wiring, not the fan - even if you measure 12VDC at the connector.

Apparently - corroded wires don't conduct current too well.

Wire Size comparison - Replacement Left side

Wonder if these other wires are important???

xr4tic · 27th June 2009, 06:51

I need to fix mine as well, it has never worked, but I know the wires are good since I'm using them to power my SPAL fan/controller that replaced the mechanical fan.

btw, that's some great info on the first post, I always thought the fan had a built-in relay, and operated at one-speed. I planned on taking mine apart, thinking that maybe just the controller portion is bad. I'll be sure to check the condition of the wires when I have it apart though.