Question about 1991 BMW 5 Series

5 Answers

Electrical System Malfunction

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?

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  • enidan97 Aug 21, 2008

    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 along with the ones in the engine compartment and the rear seat modules re-installed did the systems start again.

    The systems operated for a short period of time then went out again.

    I had opened the modules, but none of the traces appeared burned and none of the components were charred.

    One module (under the rear seat) had relays, but why would some malfunction and others not in the same module? Why would so many go at one time? Is it really the relay module, or is another module the culprit?

  • enidan97 Aug 24, 2008

    Recently, the '91 BMW 525i 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 along with the ones in the engine compartment and the rear seat modules re-installed did the systems start again.

    The systems operated for a short period of time then went out again.

    I had opened the modules, but none of the traces appeared burned and none of the components were charred.

    One module (under the rear seat) had relays, but why would some malfunction and others not in the same module? Why would so many go at one time? Is it really the relay module, or is another module the culprit?

  • enidan97 Aug 24, 2008

    My '91 BMW 525i 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 along with the ones in the engine compartment and the rear seat modules re-installed did the systems start again.

    The systems operated for a short period of time then went out again.

    I had opened the modules, but none of the traces appeared burned and none of the components were charred.

    One module (under the rear seat) had relays, but why would some malfunction and others not in the same module? Why would so many go at one time? Is it really the relay module, or is another module the culprit?

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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

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Dear Sir/madam,

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.

thanks
good luck

Posted on Aug 24, 2008

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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.

Cheers
JigSaw
Fixya Premier Support Team

Posted on Aug 24, 2008

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Take it to shop for a diagnose

Posted on Aug 21, 2008

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This sounds like a relay issue and there are so many relays that a repair shop would need to run a diagnostic test. Sounds like a anti theft/security malfunction.

Posted on Aug 21, 2008

  • kristopher betzler
    kristopher betzler Aug 24, 2008

    okay how about , checking the "pcm" relay, or the "ign" relay.
    perhaps that would help, but you really need to take it in.


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I need a schematic for the fuses on a 2002 VW Beetle. can you help me?


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hi, i recently bought a used 2001 jetta and had the same problem...auto locks, sunroof, windows, interior lights, trunk switch on door all stopped working all of a sudden. replaced fuse #14 and everything works like magic again...

I found this fuse diagram A LIFE SAVER!!!



-----------------[ S8 ][S 12][S 16][S 20]
-----------[ S5 ][ S9 ][S 13][S 17][S 21]
[ S1 ][ S3 ][ S6 ][S 10][S 14][S 18][S 22]
[ S2 ][ S4 ][ S7 ][S 11][S 15][S 19][S 23]
[ S 24 ] [ S 31 ] [ S 38 ] -- -- --
[ S 25 ] [ S 32 ] [ S 39 ] R R R
[ S 26 ] [ S 33 ] [ S 40 ] S S S
[ S 27 ] [ S 34 ] [ S 41 ] -- -- --
[ S 28 ] [ S 35 ] [ S 42 ] R R
[ S 29 ] [ S 36 ] [ S 43 ] S S
[ S 30 ] [ S 37 ] [ S 44 ] -- --

S1=10 AMP=Heated washer nozzles, glove compartment light, memory seat...
S2=10 AMP=Turn Signal System
S3=5 AMP=Fog Light Relay, Instrument Panel Dimmer Switch
S4=5 AMP=License Plate Lamps
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S6=5 AMP=Central Locking System
S7=10 AMP=Back-up Lights, Speedometer Vehicle Speed Sensor.
S8=OPEN
S9=5 AMP=Anti-Lock Brakes.
S10=10 AMP for GAS/5 AMPS for Diesel=ECM
S11=5 AMP=Instrument Cluster
S12=7.5 AMP=B+ (battery positive for data-link connector) (DLC).
S13=10 AMP=Brake Lights
S14=10 AMP=Interior Lights, Central Locking System
S15=5 AMP=Instrument Cluster, Automatic Transmission Control Module (TCM).
S16=10 AMP=A/C Clutch, After Run Coolant Pump.
S17=Open
S18=10 AMP=High Beam Right
S19=10 AMP=High Beam Left
S20=15 AMP=Low Beam Right
S21=15 AMP=Low Beam Left
S22=5 AMP=Parking and Side Marker Lights, Right
S23=5 AMP=Parking and Side Marker Lights, Left
S24=20 AMP=Front Wiper Motor, Washer Pump
S25=25 AMP=Fresh Air Blower, Climatronic, A/C
S26=25 AMP=Rear Window Defogger
S27=15 AMP=Rear Wiper Motor
S28=15 AMP=Fuel Pump, Gas Engine Only
S29=15 AMP Gas/10 AMPS Diesel=ECM
S30=20 AMP=Sunroof Control Module
S31=20 AMP=Automatic Transmission Control Module
S32=10 AMP Gas for Fuel Injectors/15 AMP Diesel for ECM
S33=20 AMP=Headlight Washer System
S34=10 AMP=Engine Control Elements
S35=30 AMP=12 VDC Outlet in Trunk
S36=15 AMP=Fog Lights
S37=10 AMP=Radio Terminal 86S, Instrument Cluster
S38=15 AMP=Central Locking System (w/ Power Windows), Luggage Compartment Light, Remote Fuel Tank Door, Rear Lid Unlock.
S39=15 AMP=Emergency Flashers
S40=20 AMP=Dual Tone Horn
S41=15 AMP=Cigarette Lighter
S42=25 AMP=Radio System
S43=10 AMP=Engine Control Elements
S44=15 AMP=Heated Seats

hope this helps ; )

Sep 14, 2008 | 2001 Volkswagen Jetta TDI

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