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BMW E30 Power Windows Stopped Working – Inoperative – 325i, 325e, 318i, M3

October 19, 2010

Q
car year: 1988
car model: 325i Convertible
All four windows of my 1988 325i convertible stopped working. They were working fine until recently. Prior to all four windows stopped working, they were sometimes not responsive when pressing the up/down switches. A couple of days ago, all four windows stopped working after they were all in the fully up positions. There was no (window) motor cranking sound when pressing the up/down buttons. Could the window circuit breaker switch faulty, or the window relays? How do replace the relay and /or circuit breaker?

A
The power window circuit on the E30 models (3-series 84-91, plus 92 convertible – 318i, 318is, 318ic, 325, 325e, 325i, 325es, 325is, 325ix, 325ic, M3) , includes a circuit breaker switch. The breaker is located either above the radio or on the center console, depending on the model. The circuit breaker switch looks like the rectangular rear defroster switch and has an image of a front window with a lighting bolt (or spark) through it.  If the system is overloaded, the breaker will “pop” and all of the windows AND the sunroof will be inoperative. In this case, the button on the breaker will pop out and show a red ring around the base of the popped out button. Simply push the button back in.

If resetting the breaker does not restore power, you may have a faulty breaker switch, a blown fuse (fuse #17) or other electrical supply problems. It is unlikely that all of the window motors have failed at the same time. If the fuse is good (just install a fresh 30 amp fuse anyway), remove the circuit breaker (it just pulls/pries out of the mounting hole in the console or faceplate) and test for power (12-volts) from the green/blue wire to ground with the key in the RUN, or IGNITION, position.  If there is power, the circuit breaker is likely faulty.  Connect the two wires (from the circuit breaker) together with a jumper and see if the windows work.  If they do (they should, if the green/blue wire has power), replace the breaker.

If there is no power at the green/blue wire (in the test above), either the fuse is faulty or you have a problem with the wiring from the fuse to the breaker (at the green/blue wire).  To further test that the rest of the system is OK, apply 12-volts (via a jumper wire) from the positive junction block under the hood, on the passenger side firewall, to the green/gray wire (the other wire that connects to the breaker) and see if the windows work.  If they do (and they should, at this point), this verifies that your problem in in the power supply side, to the breaker (via the green/blue wire … that has no power).  Further electrical tracing will be needed.  The BMW ETM (Electrical Troubleshooting Manual) contains the full vehicle wiring diagrams.  We can order this for you.  However, the Bentley repair manual has most of the electrical schematics and does include the power window schematics.

E30 chassis power window circuit breaker:

Bentley repair manual:

One Comment
  1. Fred Wong permalink

    Thanks for the information.
    After replacing the fuse #17 as suggested, all four windows operate flawlessly.

    Cheers,

    Fred

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