| All values measured to ground unless otherwise noted | |||
| A37 | |||
| 1.8 | CAN Class B bus (high side). Mid speed data transfer bus input and output, exchanges data with other ECMs | No reliable test. Check continuity of wiring. Approx. 5 VAC when data is on bus | Also ECMs can cause CAN-Bus DTCs |
| 1.9 | CAN Class B bus (low side). Mid speed data transfer bus input and output | See pin 1.8 | HHT is also used for CAN diagnosis |
| 2.1 | Power output to rear window defrost element | Ignition on, 12 VDC with rear window defroster on | After approx. 12 min. system will be switched off automatically |
| 2.2 | Circuit 30 power input | 12 VDC at all times | Feed from F4f4 |
| 2.3 | Main ground to W7 | Approx. 0 Ohms to ground | |
| K40/2 | |||
| C1.2,3 | Circuit 30 main power input | 12 VDC at all times | Feed from battery via X4 |
| C1.4 | Main ground to W1 | Approx. 0 Ohms to ground | |
| N10/1 | |||
| 2.1 | Rear window defroster switch signal input | Ignition on, 6.2-8 VDC with N22s1 held in pressed position, < 1 VDC in rest position | |
| 2.2 | Rear window defroster signal output, lights LED in A/C ECM | Ignition on, rear window defroster on: 7.2-9.2 VDC |
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| 4.1 | CAN Class B bus (low side). Mid speed data transfer bus input and output, exchanges data with other ECMs | No reliable test. Check continuity to all appropriate ECMs. Approx. 5 VAC when data is on bus | |
| 4.2 | CAN Class B bus (high side) | See pin 4.1 | |
| Note 1 | Due to various functions A37, K40/2 and N10/1 are split up in several system diagrams, therefore only the relating pins are listed. Pins not shown are unrelated to this system | ||