Question about 1991 BMW 5 Series
Recently, the cars electrical system shut down. The central locking system, the windows, seat adjustments, interior lights and the radio quit operating. The A/C, driving lights & ignition remained operative.
Removing the electrical modules in the engine compartment & re-seating them reset the system. Then the same issue recurred. Re-seating the modules did not resolve this the second time. Only when the modules under the rear seat were removed and re-installed did the systems start again.
Which module is the culprit?
Have experienced a similar problem on my 1990 525i with 200,000 miles.
Mine was caused by the battery having an internal short in one cell. Voltage would drop to 10V and electronics did weird things like locks not working or randomly locking and unlocking.
Replaced battery and problem was cured.
If the problems occur when engine is running, check alternator. It can produce electrical noise that can cause odd electrical problems. Take it out (not too difficult on a BMW) and have it tested at an automotive electrical shop (not a parts house).
Lastly, if there are engine stumbling or hesitation issues, check the engine to frame grounding strap. Its on the passenger side in the engine compartment between the frame rail below the battery and the front motor mount. Mine coroded through and was causing a bad ground connection between engine and body. Check with an ohm meter from engine to body. Should be less than 2 ohms normally.
Posted on Sep 11, 2009
First thing, check battery, alternater may not have been charging and it simply ran out of power. Depending on make of car, there are either 3-4 main fuses 3/8" X 5/8" that are either on the positive cable at the battery or in the fuse block on the drivers side inner fender. One of these may be blown. You may have fuseable links instead. This is a loop of wire that does the same thing as the fuses. Should be one of the two places. You can feel if these are burned thru. If this is the problem, what caused it must be found. Alternater likely susspect, but could be anything.
Posted on Aug 24, 2008
Electrical faults in BMW's are too complicated.
If you try and fix it yourself, you may cause more complications to your car.
I would recommend you send it to a shop that are familiar with BMW's to get it fixed.
Fixya Premier Support Team
Posted on Aug 24, 2008
Take it to shop for a diagnose
Posted on Aug 21, 2008
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Posted on Jan 02, 2017
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