I could not find any useful information on the subject so here is it for anyone who is trying to install an auxiliary electric cooler fan to a 2009 e93 335i. Using a single terminal Temperature Sending Unit:
1. follow wiring instructions from the fan to the temperature sending unit terminal.
2. The easy part is wiring the negative wire and the constant positive wire.
3. The time consuming voodoo part is wiring the remote wire to some place in the hood area... you can use the left headlight wiring harness - there is a BLACK WITH GREEN STRIPE wire that is the headlight turn on wire. NOT the green with black stripe wire.
The temperature sending unit has a positive terminal that sticks out. It will not have a negative terminal...however, the negative terminal itself is the body of the sensing unit. So what I did is wrap a wire around the body and screwed it onto the receptical of the hose where the temperature sending unit tip will make contact with. Then I attached the other end of that wire onto the car grounding bolt next to the power steering container.
Be advised, this black and green striped wire is only hot when the headlights are on or the auto mode. I tried the other green and black stripe wire which was supposed to be on when the ignition is on...but it did not work.
In order to test the sending unit, you must ground it, after all wires are hooked up as described above...then use a heat gun to heat the tip and when it to the set temperature, the fan should kick on. Make sure the ignition and lights are on.
Again, left headlight harness, Black wire green stripe. If anyone finds the true remote wire, then let us know. Otherwise, this is a less than ideal setup.
1. follow wiring instructions from the fan to the temperature sending unit terminal.
2. The easy part is wiring the negative wire and the constant positive wire.
3. The time consuming voodoo part is wiring the remote wire to some place in the hood area... you can use the left headlight wiring harness - there is a BLACK WITH GREEN STRIPE wire that is the headlight turn on wire. NOT the green with black stripe wire.
The temperature sending unit has a positive terminal that sticks out. It will not have a negative terminal...however, the negative terminal itself is the body of the sensing unit. So what I did is wrap a wire around the body and screwed it onto the receptical of the hose where the temperature sending unit tip will make contact with. Then I attached the other end of that wire onto the car grounding bolt next to the power steering container.
Be advised, this black and green striped wire is only hot when the headlights are on or the auto mode. I tried the other green and black stripe wire which was supposed to be on when the ignition is on...but it did not work.
In order to test the sending unit, you must ground it, after all wires are hooked up as described above...then use a heat gun to heat the tip and when it to the set temperature, the fan should kick on. Make sure the ignition and lights are on.
Again, left headlight harness, Black wire green stripe. If anyone finds the true remote wire, then let us know. Otherwise, this is a less than ideal setup.
