Back View of PCM Connector End View C4

Courtesy of GENERAL MOTORS CORP.
Connector Part Information		31-Pin WH
Pin	Wire Color	Function
1	BK	Ignition Positive Voltage
2	-	Not Used
3	RD/WH	Battery Voltage
4	BK/BU	Secondary AIR Solenoid Valve Control
5	BK/OG	Secondary AIR Pump Relay Control
6	-	Not Used
7	PK/BK	Heated Oxygen Sensor (HO2S) 2 Heater Circuit Control
8	-	Not Used
9	BK/OG	Ignition Positive Voltage
10	YE	AC Request Signal
11	RD/YE	MIL Control
12	GN	Electrical Load Idle-Up Signal, Tail Lamps
13	WH	Electrical Load Idle-Up Signal, Rear Defogger
14	YE	Supplemental Inflatable Restraint (SIR) System Signal
15-18	-	Not Used
19	PK	Data Link Connector (DLC)
20	PK/BK	Diagnostic Request Circuit
21	BU	Fuel Tank Pressure (FTP) Sensor Input
22-31	-	Not Used