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BMW 540I Related Questions

Do you need to know how to replace the alternator in a BMW 540I? Do you need to refill coolant in a BMW 540I? The BMW 540I has numerous safety features which are the star attraction apart from speed and spaciousness. Not being able to understand the codes displayed or the reasons for failures could cause questions to arise in the minds of owners. This is when an online Expert's experience will come in handy. Read below where Experts have answered questions regarding the BMW 540I.

Where is the blower resistor for a BMW 540I located?

It should be on the left side, behind the console, at the plenum. It is just below the tube that goes back into the console. You may also be able to follow the blower motor harness to the blower motor resistor. The wire colors should be green/gray, black, blue, and green. 

What could prevent the door locks in a 2000 BMW 540I from working while the alarm goes off for no reason?

There could be a few different things responsible for this:

A draw test to check for a battery drain would need to be carried out. Most often the blower motor resistor or electric engine fan (if fitted) causes this on this model. It could also be related to the alarm.

If the door locks don’t work, and the fuses are okay, it could be a failed general module. The general module also controls the alarm, so this could be related. However, the alarm could also be set off by a failed sensor which sends a signal saying that the car is being broken into, or possibly a low battery. Most often it is the hood latch sensor that is the cause, but it could be any of the door sensors, tilt sensor, interior protection sensor, etc. With a proper BMW scan tool, you can read out the alarm history and see what has been triggering it. A low voltage issue might also cause this; however, you could start by checking for a battery draw.

What is the procedure to refill coolant in a 1994 BMW 540I?

  • Turn the ignition on, but turn the engine off. Turn the heat on to the maximum with the fan set to ‘low.’
  • On top of the expansion tank there is a bleeder screw. Remove this screw and fill the tank up until the fluid spills out of this bleeder hole.
  • Continue pouring until no air bubbles whatsoever come out of the bleeder hole as the coolant overflows out.
  • Next, reinstall and tighten the bleeder screw. Turn the car on and let it warm up to operating temperature with the heater on in the passenger compartment to full blast.
  • Then, let it fully cool and top up the coolant tank until full. You may want to repeat a few times to make sure that all the air is out.

How to replace the water cooled alternator on a 2000 BMW 540I?

Remember to perform these tasks on an engine that has cooled down.

  • Remove the fan clutch from the water pump. You will need a 32 mm open ended wrench. Remember to turn it to the right, and not left. You will need to turn the wrench quickly to loosen the nut. There is a special tool 115050 that fits on the fan clutch nut.
  • This will be a good time to drain the coolant.
  • Unscrew the bolt and remove the battery lead.
  • Disconnect the plug.
  • Release the screw, and lay the roller to one side.
  • Release the remaining three screws on the alternator. A residual quantity of coolant will emerge when the alternator is removed.
  • Pull out the alternator towards the front.

If necessary, disconnect the upper coolant hose to help in the removal.


Replace the sealing ring on the alternator.

What could cause the sunroof on a BMW 540I to open, but not tilt?

It could be that just the button has failed. If not the switch, it could be the mechanism or the sunroof module itself. You would need to have the roof partially disassembled in order to verify exactly the cause in this case.

The switch has multiple functions inside it (it is actually a multi-switch inside), so it is possible that just one of them has failed.

The BMW 540I, though known for its safety, performance, comfort, and appearance, could sometimes face problems due to wear and tear. Trying to get an appointment with a mechanic could take time. Repair and replacement procedures may require immediate attention. In such situations, asking an Expert would be convenient. Verified Experts are available to answer questions regarding the BMW 540I from the comfort of your home. 

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