2003 x5bmwjust went over 100000 miles and transfailsafe prog problem and battery light go on and car looses power help me x5 4.4i
The transmission computer is extremely sensitive to voltage, so any problem with the charging system will cause the transmission to go into failsafe (or fail to work at all). I would therefore focus on the battery light and assume that the transmission problem will go away when the charging system is fixed. Similarly, the power loss is likely the engine control system getting confused because the system voltage is too low. That should resolve itself when the charging system is fixed.
This car came with either a Bosch or a Valeo alternator. The part that normally wears out is the brushes on the voltage regulator. What bothers me a little is that the brushes in these alternators usually last 150-175k miles, so your problem may be something other than worn brushes.
If you are handy, pull off all the plastic parts that are hiding the alternator, find the voltage regulator, which should be held to the back of the alternator with two screws (Bosch) or three screws (Valeo). Remove it and see if the carbon brushes are worn down to stubs. They are about an inch long when new or about a quarter inch long when worn out.
If the brushes are shot, don't bother trying to replace just the brushes. A new voltage regulator will run you about $75. If the brushes are still good, you may have a wiring problem or a failed alternator. Check the ground wires at the battery and at the engine mount before spending money on an alternator. A 'new' (rebuilt) alternator is about $400 at the dealer or $200 on line.
If this is your original battery, you are overdue for a battery, so replace it while you are working on the electrical system. On a 2003, you should not need to use jumper cables to keep the system powered up while you replace the battery, but it is not a bad idea. Attach the jumper cables to the connections under the hood so they are not in your way. Keeping the system powered while the battery is being changed conserves all the memories in all the computers and comfort controls, though from your description, it is a little late for that. You will have to reprogram the comfort stuff and tolerate some odd performance while the engine and transmission re-learn your climate and driving pattern.
Clean the battery clamps while the battery is out. I prefer to clean them with steel wool rather than with battery tools.
May 08, 2011 |
BMW X5 Series Cars & Trucks