Test readings, 10-pin telephone connector

Pin No.	Lead colour	Component/ Function	In/Out	Test conditions	Across	Test reading	See
1	RD	Power supply +30	-	Not connected.	1-4	B+
2	YE/GY	Power supply +15. The input is used as a logic signal for certain mobile phones.	-	Not connected. Ignition ON	2-4	B+
3	OG	Ground, microphone	-	-	-	-
4	BK	Ground, mobile phone	-	-	-	-
5	RD/BN	Telephone Mute Control	-	No telephone call. Telephone call.	5-4	4-6 V <2 V
6		Rheostat	-	-	-	-
7	OG	Telephone line output, signal	-	-	-	-
8	BN/BK	Telephone line output, ground	-	-	-	-
9		Not connected	-	-	-	-
10	YE	Microphone (low level output)	-	-	-	-