A lot of people have asked me for this info in the past so I'm just posting this here so I can just link people to it
This is what every wire in an obd2 automatic harness goes to and what wires it should go to on an 88 325is. I did add some extra info for the abs wiring. Anyways I hope this helps people get their cars up and running correctly.
C101 Wire color
Pin 1 Alternator + Blue
Pin 2 Oil level sensor full Green/yellow
Pin 3 empty Empty
Pin 4 Cluster tmperature gauge Brown/Purple
Pin 5 Oil pressure switch Brown/green
Pin 6 o2 sensor relay ( not needed ) green/white
Pin 7 Ignition switch power contstant Green
Pin 8 Economy gauge Black/white
Pin 9 RPM signal Black
Pin 10 Oil level sensor low Blue
Pin 11 service indicator reset White/green
Pin 12 Check engine Light Gray
Pin 13 Fuel pump relay Green/Purple
Pin 14 Vehicle speed sensor from cluster Black/white
Pin 15 Unlodaer relay Black/green
Pin 16 srs diagnostic wiring Black/white
Pin 17 Abs communication for ix Empty
Pin 18 Ignition switch starter Black/yellow
Pin 19 m3 oil temp ( unused ) empty
Pin 20 abs relay power for 1990+ cars red/yellow
x20
Pin 1 abs/asc?
Pin 2 abs/asc?
Pin 3 Exhaust flap solenoid (unussed for e30) Green / violet
Pin 4 a/c compressor cntrl relay (unused) Black/ blue
Pin 5 a/c pressure switch (unused for e30) Black/gray
Pin 6 Climate control module (unused for e30) purple/gray
Pin 7 EWS (Unused for e30) Green
Pin 8 pws for carbon canister/exhaust flap (unused for e30 ) red/white
Pin 9 Vss input ( normally from ASC module ) Brown/red
Pin 10 Reserve light switch
Pin 11 Engine temp sender to gauge cluster Brown/yellow
Pin 12 Engine temp sender to gauge cluster Brown/purple
Pin 13 Fuel pump relay Green/purple
Pin 14 empty
Pin 15 Starter motor side? Black/green
Pin 16 to pin 15/20 diagnostic connetor White/yellow
Pin 17 to pin 20/20 diagnostic connetor White/purple
Pin 18 Starter engage Black/yellow
Pin 19 Service indicator reset White/green
Pin 20 Engine speed Black
Pin 21 constant power with ingition on Green
Pin 22 to pin 16/20 diagnostic connetor
Pin 23 Oil pressure switch Brown/green
Pin 24 Fuel econoy gauge black/white
Pin 25 altnertor signal blue
x6031
Pin 1 Check engine light Gray
Pin 2 Carbon canister (unused for e30) Green/blue
Pin 3 Fuel consumption signal (unused for e30) Green/red
Pin 4 OBD to Diagnostic connector(unused for e30)white/purple/yellow dots
Pin 5 Fuel tank pressure sensor (unused for e30) yellow/red
Pin 6 Fuel tank pressure sensor (unused for e30) red/green-gray/white
Pin 7 Fuel tank pressure sensor (unused for e30) Brown/black
Pin 8 Power for DLC Pupple/black
Pin 9 empty
Pin 10 empty
Pin 11 empty
Pin 12 empty
c101 ------ x20
Pin 1 to pin 25 (Alternator signal)
Pin 2 to Pin ( There is no oil level sensor connector in an e36 wiring harness so you need to run your own wires here or pick an unused wire on the engine harness side and repurpose it )
Pin 3 empty
Pin 4 to pin 12 ( rewire brown/purple to new e30 temp sensor )
Pin 5 to Pin 23 ( Oil pressure switch )
Pin 6 empty
Pin 7 to pin 21 ( ignition switch power constant )
Pin 8 to pin 24 ( Fuel economy gauge )
Pin 9 pin 20 ( engine rpm speed )
Pin 10
Pin 11 to pin 19 ( service indicator reset )
Pin 12 to pin 1 ( x6031 ) ( check engine light )
Pin 13 to pin 13 ( fuel pump relay )
Pin 14 to pin 9 ( vss input from cluster )
Pin 15
Pin 16 to pin 8 ( x6031 )
Pin 17 empty
Pin 18 to pin 18
Pin 19 empty
Pin 20 for 88-89 leave empty. for 90+ wire to a red/white wire in the harness (power from DME relay). Verify wire color on chassis side. If brown DO NOT wire to power.
This is what every wire in an obd2 automatic harness goes to and what wires it should go to on an 88 325is. I did add some extra info for the abs wiring. Anyways I hope this helps people get their cars up and running correctly.
C101 Wire color
Pin 1 Alternator + Blue
Pin 2 Oil level sensor full Green/yellow
Pin 3 empty Empty
Pin 4 Cluster tmperature gauge Brown/Purple
Pin 5 Oil pressure switch Brown/green
Pin 6 o2 sensor relay ( not needed ) green/white
Pin 7 Ignition switch power contstant Green
Pin 8 Economy gauge Black/white
Pin 9 RPM signal Black
Pin 10 Oil level sensor low Blue
Pin 11 service indicator reset White/green
Pin 12 Check engine Light Gray
Pin 13 Fuel pump relay Green/Purple
Pin 14 Vehicle speed sensor from cluster Black/white
Pin 15 Unlodaer relay Black/green
Pin 16 srs diagnostic wiring Black/white
Pin 17 Abs communication for ix Empty
Pin 18 Ignition switch starter Black/yellow
Pin 19 m3 oil temp ( unused ) empty
Pin 20 abs relay power for 1990+ cars red/yellow
x20
Pin 1 abs/asc?
Pin 2 abs/asc?
Pin 3 Exhaust flap solenoid (unussed for e30) Green / violet
Pin 4 a/c compressor cntrl relay (unused) Black/ blue
Pin 5 a/c pressure switch (unused for e30) Black/gray
Pin 6 Climate control module (unused for e30) purple/gray
Pin 7 EWS (Unused for e30) Green
Pin 8 pws for carbon canister/exhaust flap (unused for e30 ) red/white
Pin 9 Vss input ( normally from ASC module ) Brown/red
Pin 10 Reserve light switch
Pin 11 Engine temp sender to gauge cluster Brown/yellow
Pin 12 Engine temp sender to gauge cluster Brown/purple
Pin 13 Fuel pump relay Green/purple
Pin 14 empty
Pin 15 Starter motor side? Black/green
Pin 16 to pin 15/20 diagnostic connetor White/yellow
Pin 17 to pin 20/20 diagnostic connetor White/purple
Pin 18 Starter engage Black/yellow
Pin 19 Service indicator reset White/green
Pin 20 Engine speed Black
Pin 21 constant power with ingition on Green
Pin 22 to pin 16/20 diagnostic connetor
Pin 23 Oil pressure switch Brown/green
Pin 24 Fuel econoy gauge black/white
Pin 25 altnertor signal blue
x6031
Pin 1 Check engine light Gray
Pin 2 Carbon canister (unused for e30) Green/blue
Pin 3 Fuel consumption signal (unused for e30) Green/red
Pin 4 OBD to Diagnostic connector(unused for e30)white/purple/yellow dots
Pin 5 Fuel tank pressure sensor (unused for e30) yellow/red
Pin 6 Fuel tank pressure sensor (unused for e30) red/green-gray/white
Pin 7 Fuel tank pressure sensor (unused for e30) Brown/black
Pin 8 Power for DLC Pupple/black
Pin 9 empty
Pin 10 empty
Pin 11 empty
Pin 12 empty
c101 ------ x20
Pin 1 to pin 25 (Alternator signal)
Pin 2 to Pin ( There is no oil level sensor connector in an e36 wiring harness so you need to run your own wires here or pick an unused wire on the engine harness side and repurpose it )
Pin 3 empty
Pin 4 to pin 12 ( rewire brown/purple to new e30 temp sensor )
Pin 5 to Pin 23 ( Oil pressure switch )
Pin 6 empty
Pin 7 to pin 21 ( ignition switch power constant )
Pin 8 to pin 24 ( Fuel economy gauge )
Pin 9 pin 20 ( engine rpm speed )
Pin 10
Pin 11 to pin 19 ( service indicator reset )
Pin 12 to pin 1 ( x6031 ) ( check engine light )
Pin 13 to pin 13 ( fuel pump relay )
Pin 14 to pin 9 ( vss input from cluster )
Pin 15
Pin 16 to pin 8 ( x6031 )
Pin 17 empty
Pin 18 to pin 18
Pin 19 empty
Pin 20 for 88-89 leave empty. for 90+ wire to a red/white wire in the harness (power from DME relay). Verify wire color on chassis side. If brown DO NOT wire to power.
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