1990 325is restomod project aka "Klaus"

[R3Z3N]

So, Terraphantm posted on bimmerforums how the Aux Fan is controlled for AC. With this note, I would make sure the coolant temp is in the lower hose so that the routine can compare high/low values:

The aux fan will also come on if the radiator outlet temperatures exceed the normal range. Depending on the increasing temps it will 'pulse-up' to almost 95% (possibly more) duty cycle in extreme and urgent case.

Just to be complete this is the precise behavior of the aux fan (assuming we're talking about the M5):

The DME takes the radiator outlet temperature and pushes into the function KL_ELU_TKA (seen below). If the radiator outlet temperature is bad, the DME takes the value from the block sensor, subtracts 10, and pushes that into the function. The output from the function is the duty cycle determined from the coolant temp; the output is held in a register until later.

Next, the DME tries to figure out what the AC's requested duty cycle is. If the compressor is off or the intake air temperature is less than 10ºC, it assumes 0. If there's an error on the IHKA side, the DME assumes 60%. Otherwise the IHKA well send a message over the can-bus (through the instrument cluster) requesting 1 of 16 speeds. The DME takes that number, and uses one of the K_ELU_KKOS[*of16] values. The resulting value is stored in a register.

The two registers are compared, and the DME picks the larger number. So if the speed request due to the coolant temp is higher than the request due to the AC, it will pick that.

Next, the DME checks the intake air temperature. If it is 60ºC or higher, the requested speed will be set 60% unless the previously calculated value is higher than 60%.

Once the requested duty cycle is settled, the DME will calculate a factor based on the vehicle speed. That factor will be multiplied by the requested duty cycle to get the final duty cycle, and this is what the fan speed is set to. In the case of the M5, the factor is 1.0 until the vehicle reaches 120 km/h, and reaches 0 by 150 km/h. Between 120 and 150, the factor will be an interpolated value.

See the image below for the referenced maps / values




The point worth noting is that there is a decent bit of redundancy built into the system. Even if the coolant outlet temperature fails, the aux fan should turn on unless you have multiple sensor failures. Other contemporary BMWs should be similar, but the temperatures, duty cycle values, and speed factors will vary.

[R3Z3N]

I don't have the OEM Aux Fan either, but instead a 16" fan up front at the condenser (I think your the same). Again with this, the relays will not be controlling anything as we will keep them closed by bridging the Temp Switch Plug.

There is a resistor (was screwed to the stock aux fan) off the 3 pin wiring under the headlight. The OEM aux fan was connected to both high and low speed relays on the hot side, the low side just had the resistor inline (hence why the fan ran slower, it didn't get full power )

As to the E46 AC Pressure sensor, it won't thread into the dryer from the E30. Check out Gary's here
NOTE: E46 AC Pressure sensor is optional. The DME can still control the fan but it will not alter the speeds in direct relation to AC Load. It will be estimated.

[Staszek]

^Alright, proper power to the fan:

1) Cut out the Aux fan resistor. That will disable the lower fan speed which is done by dropping power through the resistor.

2) Radiator temp switch PLUG, bridge pins 1 and 3 (GN/BK) and (BK/BN).

NOTE:
(You could seal the rad port at this point if you want) You could even use this port for the E46 radiator temp SENSOR instead of the lower rad hose method (assuming it threads in). This is still only triggered only when the car is on and still goes through the unloader relays so the fan won't take power upon start should the DME try. WOOT!

This will keep the full "high speed" power running to the PWM module which is controlled via the DME. And now you can tune your fan to your needs! BTW the Z3M had a smaller radiator, hence why it probably had a more aggressive fan curve.

If you don't use the PWM module, you will keep the E30 wiring and will function as the E30 did. Gary CAN controller then only helps kick the idle up (by telling DME over CAN) and trigger the AC Compressor

I dont have an OEM AUX FAN, its a SPAL, havent checked but is there a resister there as well? I am not by the car.

[R3Z3N]

^Alright, proper power to the fan:

1) Cut out the Aux fan resistor. That will disable the lower fan speed which is done by dropping power through the resistor.

2) Radiator temp switch PLUG, bridge pins 1 and 3 (GN/BK) and (BK/BN).

NOTE:
(You could seal the rad port at this point if you want) You could even use this port for the E46 radiator temp SENSOR instead of the lower rad hose method (assuming it threads in). This is still only triggered only when the car is on and still goes through the unloader relays so the fan won't take power upon start should the DME try. WOOT!

This will keep the full "high speed" power running to the PWM module which is controlled via the DME. And now you can tune your fan to your needs! BTW the Z3M had a smaller radiator, hence why it probably had a more aggressive fan curve.

If you don't use the PWM module, you will keep the E30 wiring and will function as the E30 did. Gary CAN controller then only helps kick the idle up (by telling DME over CAN) and trigger the AC Compressor

[Staszek]

^The coding will allow you to tune when the fan comes on and off at desired temps and speeds at the duty cycle you desire.

Read the wiring again. 1 from X60004 to PWM module, the other two will be switched +12v and Ground.

The E30 uses a relay based trigger with the temp sensor and resistor that triggers high or low RPM which you will bypass however you desire. I would use the existing wiring but keep it triggered with ignition on at the relay, which would be to bridge the relay on at all times as you don't rely on the old temp sensor to trigger the relay. Best to go through the E30 Wiring PDF and see how it triggers the relays and bypass that.

Thanks for this!

[R3Z3N]

^The coding will allow you to tune when the fan comes on and off at desired temps and speeds at the duty cycle you desire.

Read the wiring again. 1 from X60004 to PWM module, the other two will be switched +12v and Ground.

The E30 uses a relay based trigger with the temp sensor and resistor that triggers high or low RPM which you will bypass however you desire. I would use the existing wiring but keep it triggered with ignition on at the relay, which would be to bridge the relay on at all times as you don't rely on the old temp sensor to trigger the relay. Best to go through the E30 Wiring PDF and see how it triggers the relays and bypass that.

[masterofnone]

Ok I hate when I don't know something.

I believe to use the E46 PWM module for the front AUX fan:
X60004 to MSS54/HP
Pin 4: Signal to PWM module
Pin 38: Ground from lower rad temp sensor
Pin 39: Signal from lower rad temp sensor

PWM Module:
3 Wire side Blue/Red/Black
Blue: Signal from X6004 Pin 4
Red: +12V (not sure if switched....but most likely yes as I don't think it has the ability to run after power off as the DME is switched power) (12 guage wire or larger)
Black: Ground
2 Wire Side Black/RED
Black to fan
Red to fan

Garry's CAN Box:
Pin 2: AC Pressure Sensor Pin 3
Pin 1: AC Pressure Sensor Pin 2

Since your using the PWM fan (WOOT!) you can control the duty cycle in regards to temp with:

KL_ELU_TKA E46M3
Operation/speed (%) 
 49°C     0%
 50°C     30%
 70°C     40%
 80°C     65%
 85°C     83%
 90°C     100% 

KL_ELU_TKA Z3M
Operation/speed (%) 
 39°C     0%
 40°C     33%
 60°C     49%
 70°C     65%
 80°C     83%
 90°C     100% 

And how that duty cycle is applied at speed:

KL_ELU_V E46M3
 0 km/h      1
 50 km/h     1
 100 km/h    1
 120 km/h    0.5
 140 km/h    0
 200 km/h    0 

KL_ELU_V Z3M
 0 km/h      1
 50 km/h     1
 100 km/h    1
 150 km/h    1
 200 km/h    0.5
 255 km/h    0 

Meaning at 120km/h whatever temp you are at, the duty cycle will be halved (E46M3). Above 140km/h the fan will be off no matter the temp.

Ive been trying to wrap my head around the PWM/CAN/AUX situation for months! This is good info!

So I see you reference the X60004 connector. Does that mean I need to run the wires directly from the PWM controller to the X60004? If so, does that mean the original E30 3-pin fan connector on the chassis is left unplugged?

And what is this reprogramming talk? Is the CAN controller not already setup for this and a possible puller fan?

[R3Z3N]

Ok I hate when I don't know something.

I believe to use the E46 PWM module for the front AUX fan:
X60004 to MSS54/HP
Pin 4: Signal to PWM module
Pin 38: Ground from lower rad temp sensor
Pin 39: Signal from lower rad temp sensor

PWM Module:
3 Wire side Blue/Red/Black
Blue: Signal from X6004 Pin 4
Red: +12V (not sure if switched....but most likely yes as I don't think it has the ability to run after power off as the DME is switched power) (12 guage wire or larger)
Black: Ground
2 Wire Side Black/RED
Black to fan
Red to fan

Garry's CAN Box:
Pin 2: AC Pressure Sensor Pin 3
Pin 1: AC Pressure Sensor Pin 2
Pin 6: Ground and to AC Pressure Sensor Pin 1

Since your using the PWM fan (WOOT!) you can control the duty cycle in regards to temp with:

KL_ELU_TKA E46M3
Operation/speed (%) 
 49°C     0%
 50°C     30%
 70°C     40%
 80°C     65%
 85°C     83%
 90°C     100% 

KL_ELU_TKA Z3M
Operation/speed (%) 
 39°C     0%
 40°C     33%
 60°C     49%
 70°C     65%
 80°C     83%
 90°C     100% 

And how that duty cycle is applied at speed:

KL_ELU_V E46M3
 0 km/h      1
 50 km/h     1
 100 km/h    1
 120 km/h    0.5
 140 km/h    0
 200 km/h    0 

KL_ELU_V Z3M
 0 km/h      1
 50 km/h     1
 100 km/h    1
 150 km/h    1
 200 km/h    0.5
 255 km/h    0 

Meaning at 120km/h whatever temp you are at, the duty cycle will be halved (E46M3). Above 140km/h the fan will be off no matter the temp.

[Staszek]

^Ah good! Are you using the front AUX PWM? If so, would you mind documenting how it wires in and same with the lower rad hose temp sender? I want to but am at a loss (though I get what plugs into Garys controller...)

What are you doing for the puller fan? Which one btw too? Being in CA summers, I want the added cooling.

I am having a shop help me with that wiring, I will diagram out what they do.

As for the puller fan I have both a SPAL pusher for the AUX and a SPAL Puller for the rad fan.

[R3Z3N]

^Ah good! Are you using the front AUX PWM? If so, would you mind documenting how it wires in and same with the lower rad hose temp sender? I want to but am at a loss (though I get what plugs into Garys controller...)

What are you doing for the puller fan? Which one btw too? Being in CA summers, I want the added cooling.

[Staszek]

^Are you holding back because you want oil temp pulled from the CAN data and converted to Analog? I would not hold my breath for that, just wire it in through the fusebox grommet. It would have been nice to have a gui to modify his controller, but it sounds like too much effort for the cost of sale and one man.

No, I need a few of the pin's reprogrammed for my Aux and Puller fan. I got ahold of Gary he is going to send me a file tonight hopefully.

[R3Z3N]

^Are you holding back because you want oil temp pulled from the CAN data and converted to Analog? I would not hold my breath for that, just wire it in through the fusebox grommet. It would have been nice to have a gui to modify his controller, but it sounds like too much effort for the cost of sale and one man.

[slum dog]

Yeah the only thing missing is fresh paint other than that, build is well executed. Really like how the interior came together and that engine bay!!! Beautiful, in for some strong pull vids please.

[Staszek]

Yoooo! Congrats man! I couldn’t help but to smile and share in your excitement hearing that thing start up.

Thanks man, I am getting itchy to finish and drive now! I need to get this can bus thing figured out. I cant get a hold of Gary to help me reprogram it.

[masterofnone]

Yoooo! Congrats man! I couldn’t help but to smile and share in your excitement hearing that thing start up.