HELP: Where is the fan relay and fuse?

[ZStig]

is it behind the glove box? Is there another set of relays or fuses? My fan is not kicking in

[StickMon]

In the box next to the brake fluid reservoir?
Just guessing here. I'm at a loss too, and searching isn't cutting it.

[ZStig]

Originally Posted by StickMon

In the box next to the brake fluid reservoir?
Just guessing here. I'm at a loss too, and searching isn't cutting it.

the ECU is there, along with 2 relays. not sure what they're responsible for, and what a bad one would look like.

My fan wasn't turning on earlier while the water temps went up and boiled. A few hours later, fan is turning on. I checked all the fuses behind the glove box. I'm at a loss

[Shipkiller]

I added the Power Distribution block and F61 Fuse location.

http://www.shipkiller.com/Engine_Cooling.html

[ZStig]

Originally Posted by Shipkiller

I added the Power Distribution block and F61 Fuse location.

http://www.shipkiller.com/Engine_Cooling.html

Odd, I'm not sure that set was immediately visible when I plunked down the glovebox. Is it hidden somewhere above?

[StickMon]

According to that schematic, there is no separate relay.
It's built into the fan, and may be a solid state relay (it's drawn as a transistor).
Pin 1 is power, pin 2 is ground, pin 4 is on/off signal.

What I did find during searching is that one of the coolant temp sensors is more likely the culprit.

Thanks for the info, Ship.
(It's a thermistor, not a varistor. Not meaning to rip. Just saying.)

[ZStig]

well, I ripped out my passenger knee airbag and found some more bolted down relays up there, but didn't have the willpower to retrieve any of them. I figure if one was burned out, the fan wouldn't be turning on in the first place

[StickMon]

Since it's intermittent, I think you've got a loose connection.
Probably at one of the sensors.
Inspect and reseat the sensor and fan connectors.

There is no relay.

[ZStig]

apparently taking the coolant temperature sensor, allows coollant to spray on your face. hahahaha. thankfully it wasn't hot.

I'm getting yellow water temp warnings, which make me think that the sensor is working. Is that a wrong assumption?

I re-connected the fan connectors near the top of it

[StickMon]

It means at least one of the sensors is working.
According to the schematic from Ship, and RealOEM, there's a thermistor and a switch.

Maybe the thermistor feeds the DME and drives the yellow light, and the switch just turns the fan on and off.
Or in your case, sometimes turns the fan on and off.

For the price, I'd replace both. Since you've already had your coolant bath.

[ZStig]

thank you very much. I hope I can get this done before the 4 day weekend

[Shipkiller]

You did not read correctly. Both are temperature sensors. One reads temperature out of the radiator and one reads temperture at the cylinder head. Both sensors are of the same type according to the WDS. They are not switchs. The DME directly controls the operation of the fan.

Before replacing any sensors I would check to see if the DME is reporting a sensor error and storing a code. I would also check for connector corrosion, loose pins and possible harness issue from the DME to the fan. One thing you have not mentioned. The fan. The fan may have a dead spot in the comutator and may not start if the stator is in a certain posistion but starts in others.

Coolant Temperature Sensor at Radiator Outlet
This temperature sensor is fitted in the outlet hose of the radiator and registers the coolant temperature after it flows out of the radiator.
The quantitative signal of the sensor is the most important factor for activation of the electric fan. The engine management system activates the electric fan.


Electric fan, S54 engine
Under certain operating conditions, the engine control activates the electric fan at various speeds.

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.

Coolant temperature sensor, S54 engine
The temperature sensor is screwed into the cylinder head. A varistor (NTC = Negative Temperature Coefficient) serves as the measure for the coolant temperature. A resistor of this kind is also used to sense the radiator outlet temperature.

The coolant temperature sensor, S54 engine, also serves as a measured variable for the following functions:
Start volume calculation
Injection volume calculation
Nominal idle speed

In the event of the sensor failing, a fault code is entered in the DME control module and a substitute value is calculated from the value of the intake air temperature sensor with the aid of a temperature model.

[StickMon]

That's a fair cop.
They're both drawn as sensors on the schematic, but ECS threw me by calling it a switch.

[Shipkiller]

Normally on a BMW, you have to replace the sensors because the O-ring had deformed and it now leaks.... If only you could by an O-ring from BMW! You have to source it yourself or buy a whole new sensor.

[ZStig]

the big plug on the top of the fan, with the 3 prongs, isn't getting any power to it..

wish I could find the damn fuse. I'll check behind the airbag again

[StickMon]

Should be at the top of the fuze block behind the glove box. F61.
It'll be a whopper.
See this pic from Shipkiller:

[ZStig]

Originally Posted by StickMon

Should be at the top of the fuze block behind the glove box. F61.
It'll be a whopper.
See this pic from Shipkiller:

Attachment 884140

Found F61. its held down by 8mm nuts. I put a tester on both ends, and it lit up, so I'm assuming that its allowing current to go through, and I shouldn't have to go through the trouble of removing it. (very little clearance to work there)


oddly enough, fuse 32 isn't even getting power to it. Tried swapping another 7.5A fuse to it, and still no light on my tester... hmmm. I could have sworn it was working before. Either way, turning the AC on does not start the fan up

[ZStig]

well, here's F61, looks solid to me, and when it was in the car, it was passing electricity to the bottom (non powered) terminal

the other pic is the red terminal in the engine bay, on the firewall. Shouldn't this be a hot wire with electric going to it? For some reason mine isn't. Everything else in the car seems to function other than the engine fan. I'm confused

[StickMon]

Originally Posted by ZStig

Shouldn't this be a hot wire with electric going to it?

Thought so, but as a sanity check, just checked mine and it's 12.52 Vdc with car off, keys out. So yea.

You said you have power on both ends of F61, but "the big plug on the top of the fan, with the 3 prongs, isn't getting any power to it."
There's a direct connection from F61 to pin 2 on the fan connector.

[ZStig]

Originally Posted by StickMon

Thought so, but as a sanity check, just checked mine and it's 12.52 Vdc with car off, keys out. So yea.

You said you have power on both ends of F61, but "the big plug on the top of the fan, with the 3 prongs, isn't getting any power to it."
There's a direct connection from F61 to pin 2 on the fan connector.

must be a cut wire...

odd I'm not getting power at that big red connector on the engine firewall too

[StickMon]

You sure your tester/meter isn't flaky?

[ZStig]

Originally Posted by StickMon

You sure your tester/meter isn't flaky?

it works on all the fuses...