| All values measured to ground unless otherwise noted | |||
| N19 | |||
| 1 | Circuit 30 power input | 12 VDC at all times | Feed from F1f30 |
| 3 | Sensors common ground in A/C system | Approx. 0 Ohms to ground | Feed from Z6/16 |
| 4 | Defrost indicator input activates LED integrated in defrost switch | Approx. 8 VDC in defrost mode | Feed from N10-3 pin 3.48 |
| 5 | Serial port II, transmits data to instrument cluster (A1 internally adapted to CAN) | No reliable test. Approx. > 0.2 VAC with engine at idle | Note 1 See pin 18 |
| 6 | No pin information available | No reliable test | as of MY 2001 |
| 7 | Signal output, blower speed control | Ignition on: Blower switch in fan stage: (1) 1.1-1.8 VDC (2) 2.0-2.6 VDC (3) 2.8-3.3 VDC (4) 3.6-4.3 VDC (5) 5.0-6.0 VDC |
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| 8 | Switched ground signal output, activates coolant circulation pump | Disconnect pump motor: 2-4 Ohms across pins of motor |
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| 9 | Switched ground signal output (logic level), activates left side water valve | Ingition on, after 15 seconds: red range detent: < 1 VDC blue/range detent: 12 VDC |
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| 10 | Switched ground signal output (logic level), activates right side water valve | Ignition on, after 15 seconds: red range detent: < 1 VDC blue/range detent: 12 VDC |
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| 12 | Main ground to W1 | Approx. 0 Ohms to ground | |
| 13 | Defrost switch signal output, activates power relay located in A37 | Ignition on, approx. 7 VDC with defrost switch held in depressed position (0 VDC in rest position) | See PE67.29 |
| 14 | Voltage output, supplies refrigerant pressure sensor | 4.75-5.25 VDC with ignition on | |
| 16 | Switched ground signal output, activates fresh/recirculated air flap switchover valve | Ignition off: Approx. 40-55 Ohms |
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| 17 | "Diagnostic port" for readout and diagnostic purpose Stored DTC data is memory persistent! |
No reliable test | |
| 18 | Serial port I, receives data from instrument cluster (A1 internally adapted to CAN) | No reliable test. > 1.5 VAC with engine at idle | Note 1 See pin 5 |
| 19 | No pin information available | No reliable test | |
| 20 | Voltage output activates A/C compressor | A/C system on, defrost on, EC off:12 VDC with A/C compressor on | |
| 21 | Circuit 15 power input | 12 VDC with ignition on | Feed from F1f20 |
| 22 | Circuit 15x power input | 12 VDC with ignition on | Feed from N73 |
| 24 | Evaporator temperature signal input. | Ignition off: 10 ° C 5.2-5.8 kOhms 20 ° C 3.2-3.6 kOhms 30 ° C 2.0-2.3 kOhms 45 ° C 1.1-1.25 kOhms |
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| 25 | Heater core signal input, right side. | Ignition off: 10 ° C 19.0-21.2 kOhms 20 ° C 11.9-13.2 kOhms 30 ° C 7.7-8.4 kOhms 45 ° C 4.2-4.6 kOhms |
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| 26 | Heater core signal input, left side. | Ignition off: 10 ° C 19.0-21.2 kOhms 20 ° C 11.9-13.2 kOhms 30 ° C 7.7-8.4 kOhms 45 ° C 4.2-4.6 kOhms |
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| 27 | Refrigerant pressure sensor signal input, used to protect A/C compressor when pressure drops. | Ignition on: 2 bar 0.5-0.75 VDC 10 bar 1.4-1.8 VDC 18 bar 2.4-2.8 VDC 28 bar 3.5-4.0 VDC |
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| 2,11,15,23,28,29 | Pins not used | ||
| N76 | |||
| 1 | Power output low side, supplies electric cooling fan |
see pin 4 | |
| 2 | Main ground to W16/3 | Approx. 0 Ohms to ground or 12 VDC to pin 3 | |
| 3 | Circuit 30 power input | 12 VDC at all times | Feed from F1f38 |
| 4 | Switched power output, activates electric cooling fan | measure to pin 1: > 2VDC when activated, voltage raises with increasing fan speed | |
| 5 | Signal input from engine control module, controls A/C system | Engine at idle, measure to 12 VDC ECT < 70 °C 1-1.9 VDC fan not running A/C on 2-4 VDC fan running ECT > 85 °C 2.5 -12.5 VDC fan running |
Feed from N3/10 |
| 6 | Circuit 15 power input | 12 VDC with ignition on | Feed from N10/1 |
| N65/1 | |||
| 1 | Circuit 30 power input | 12 VDC at all times | Feed from F1f38 |
| 2 | Switched power output, activates left electric cooling fan | measure to pin 4: > 2VDC when activated, voltage raises with increasing fan speed | |
| 3 | Main ground to W16/3 | Approx. 0 Ohms to ground or 12 VDC to pin 3 | |
| 4 | Switched power output, activates right electric cooling fan | measure to pin 4: > 2VDC when activated, voltage raises with increasing fan speed | |
| 5 | No pin information available | No reliable test | |
| Note 1 | Rx - ambient temperature A1p4 - ECT (A1p7) - speed (A1p8) - rpm signal (A1p5) - illumination circuit 58d - acceleration recognition Tx - rpm increase - refrigerant pressure |
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| Note 2 | Refer to D. M. Climate Control Vol. 1, 1.6 | ||