From what I remeber its a red with yellow dots, idk about x5 but you can test with the same colored wire from radio, can you post a pic of the brown plug wires in back of the heated seat dsc switch cluster

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-e24 m6
-e32 740/5
-e34 525it
-e83
-e83 Msport (gf)
-e30 325ix (gf)