1990 BMW 325is AutomaticFACTORY OEM SERVICE PROCEDURE

System Tests

NOTE:
  1. Power supplied to security system comes from radio connectors (Battery, IGN/ACC, GND).
  2. Check connection between main connector and Control Unit, then replace Control Unit only when all tests prove okay.
MAIN CONNECTOR WIRING TEST

Test No. & Wire Color Function Test Conditions Desired Result Possible Fault
1. Brown Ground All Continuity To Ground Loose Connection, Open Wire, Check Connection To Radio
2. Violet Ignition Or At A/C Ignition ON B+ Loose Connection, Open Wire, Check Connection To Radio
3. Yellow Battery All B+ Blown 5 amp Alarm Fuse (ATC Blade Type), Loose Connection, Check Connection With Radio, Open Wire
4. Black/White Door Sensor a) All Doors Closed b) Any Door Opened a) Continuity To Ground - OPEN, b) Continuity To Ground (1) Connected To Wrong Wire On Car Side, Loose Connection On Connector M, Open Wire
5. Red Siren All Siren Should Emit Sound Loose Connection, Poor Ground On Siren Black Wire, Open Wire
6. Black Ground Main Connector Connected To Control Unit Continuity To Ground Open In Control Unit
7. Blue (Option) Trunk Sensor (Option) a) Trunk Closed b) Trunk Open a) Continuity To Ground - OPEN, b) Continutiy To Ground (2) Connected To Wrong Wire On Car Side, Loose Connection, Open Wire
8. Violet LED Battery Ignition & Ground Wires Connected Properly LED Should Flash Twice When Connecting Main Connector To Control Unit Loose/Wrong Connection On LED 2-Pin Connector, Defective LED, Defective Control Unit, Open Wire
9. Blue/Yellow Door Lock (Negative) All Attach To Ground: Doors Should Lock Loose Connection, Open Wire, Connected To Wrong Wire
10. Blue/Green Door Unlock All Attach To Ground: Doors Should Unlock Loose Connection, Open Wire, Connected To Wrong Wire
11. Blue/Yellow Door Lock (Positive) All Apply Battery: Door Should Lock Loose Connection, Open Wire, Connected To Wrong Wire
12. Blue/Green Door Unlock (Positive) All Apply Battery: Door Should Unlock Loose Connection, Open Wire, Connected To Wrong Wire
(1) If diode module is used, test point is not directly connected to ground.
(2) If transistor module is used, test point is not directly connected to ground.
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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