BMWAG
Electrical troubleshooting manual
5 Series - E34 (518i, 520i, 525td, 525tds, incl. touring) Schematics Model year 1994

Automatic climate control with filter (IHKR/F3)
Scheme 6450.5

Pin Assignment
A=X1815526-pin, white
B=X1815626-pin, black
C=X1815726-pin, blue
Pin Assignment X18155
PinTypeDescription/FunctionConnection
1not used
2ERight heat exchanger temperatureRight heat exchanger sensor
3ELeft heat exchanger temperatureLeft heat exchanger sensor
4EOutside temperatureOutside temperature sensor
5EEvaporator temperatureEvaporator sensor
6ESetpoint, mixing air actuatorMixing air actuator
7ESignal, independent ventilationRelay box, independent heating/ventilation
8ESpeedometer A signalInstrument cluster
9not used
10ESignal, independent heatingRelay box, independent heating/ventilation
11not used
12ETerminal 58KLight switch/lights
13ASupply voltage for function lightsIHKR/F3 push button unit
14ASupply voltage for mixing air actuatorMixing air actuator
15MGround for regulator in operating unitIHKR/F3 operating unit
16MGround for all sensorsAll temperature sensors
17MGroundMixing air actuator
18EPush button unit lightsIHKR/F3 push button unit
19not used
20ESignal, air condition ONIHKR/F3 push button unit
21ESignal, recirculated air/AUC ONIHKR/F3 push button unit
22ESignal, rear window defogger ONIHKR/F3 push button unit
23EFunction indicator, air conditioning ONIHKR/F3 push button unit
24EFunction indicator, rear window defogger ONIHKR/F3 push button unit
25EFunction indicator, AUC ONIHKR/F3 push button unit
26EFunction indicator, recirculated air ONIHKR/F3 push button unit
E = Input, A = Output, M = Ground
Pin Assignment X18156
PinTypeDescription/FunctionConnection
1MGroundGround connection
2not used
3EInterior temperatureInterior temperature sensor in IHKR/F3 operating unit
4ESetpoint, fresh airIHKR/F3 operating unit
5ESetpoint, left blowerIHKR/F3 operating unit
6ESetpoint, right blowerIHKR/F3 operating unit
7not used
8ESignal AUC ONAUC control unit
9ASignal, air conditioning ONDiode module
10MGroundGround connection
11not used
12ETerminal 30Fuse
13ETerminal 30Fuse
14not used
15Emax. heating, rightIHKR/F3 operating unit
16not used
17not used
18ESignalRelay box, independent heating/ventilation
19not used
20not used
21not used
22Emax. heating, leftIHKR/F3 operating unit
23ETerminal 15Fuse
24not used
25ETerminal 61Unloader relay
26ETerminal 30 hGenerator
E = Input, A = Output, M = Ground
Pin Assignment X18157
PinTypeDescription/FunctionConnection
1AVoltage supply for actuatorsall actuator motors
2AVoltage supply for actuatorsall actuator motors
3not used
4not used
5not used
6ASignal, recirculated airRecirculated air flap motor
7ASignal, recirculated airRecirculated air flap motor
8ASignal, recirculated airRecirculated air flap motor
9ASignal, recirculated airRecirculated air flap motor
10ASignal, fresh airFresh air flap motor
11ASignal, fresh airFresh air flap motor
12ASignal, fresh airFresh air flap motor
13ASignal, fresh airFresh air flap motor
14AVoltage supply for potentiometerIHKR/F3 operating unit
15ARxD diagnosis lineDiagnostic connector
16E/ATxD diagnosis lineDiagnostic connector
17not used
18ASignal, interior sensor blowerInterior sensor blower motor
19ASignal, auxiliary water pumpAuxiliary water pump relay
20ASignal, rear window defogger ONRear window defogger relay
21not used
22ASignal, A/C compressor ONPressure switch B8y
23ASignal, air mixingMixing air flap motor
24ASignal, air mixingMixing air flap motor
25ASignal, air mixingMixing air flap motor
26ASignal, air mixingMixing air flap motor
E = Input, A = Output, M = Ground