Fig 1: Connector End View

Courtesy of GENERAL MOTORS CORP.

Connector Part Information

OEM: 34566-2503
Service: 88988931
Description: 73-Way F Micro-Pack 64 Series (BK)

Terminal Part Information

Pins: 1-5, 8, 9, 11-14, 17, 20, 23, 27, 29, 30, 32, 33, 35, 36, 39, 42-44, 46, 48, 50, 53, 56, 59, 62-64, 66-69, 71, 72
Terminal/Tray: See Terminal Repair Kit
Core/Insulation Crimp: See Terminal Repair Kit
Release Tool/Test Probe: See Terminal Repair Kit

Pins: 73
Terminal/Tray: 7116-4152-02/9
Core/Insulation Crimp: 2/5
Release Tool/Test Probe: 12094430/J-35616-35 (VT)

Connector Terminal Identification

Pin	Wire Color	Circuit No.	Function
1	PU	2121	Ignition Control (1)
2	TN/WH	3111	Heated Oxygen Sensor Low Signal Sensor 1
3	PU/WH	3110	Heated Oxygen Sensor High Signal Sensor 1
4	PU/WH	1668	Heated Oxygen Sensor High Signal Sensor 2
5	TN/WH	1669	Heated Oxygen Sensor Low Signal Sensor 2
6-7	-	-	Not Used
8	D-BU	496	Knock Sensor Signal
9	GY	1716	Knock Sensor Signal
10	-	-	Not Used
11	YE	581	TAC Motor Control (1)
12	BN	582	TAC Motor Control (2)
13	PK/BK	5290	Ignition 1 Voltage
14	PK/BK	6395	CMP Actuator Solenoid Control Intake
15-16	-	-	Not Used
17	L-BU	2123	Ignition Control (3)
18-19	-	-	Not Used
20	GY	5296	Low Reference
21-22	-	-	Not Used
23	TN	5301	Low Reference
24-26	-	-	Not Used
27	PU	574	Low Reference
28	-	-	Not Used
29	TN	2752	Low Reference
30	L-GN	5282	Low Reference
31	-	-	Not Used
32	L-GN/BK	1745	Fuel Injector (2) Control
33	D-GN/WH	2124	Ignition Control (4)
34	-	-	Not Used
35	BN	2129	Low Reference
36	YE/BK	5297	5-Volt Reference
37-38	-	-	Not Used
39	D-BU	5300	5-Volt Reference
40-41	-	-	Not Used
42	TN	2760	Low Reference
43	L-GN	2867	5-Volt Reference
44	GY	2701	5-Volt Reference
45	-	-	Not Used
46	PU	5284	Low Reference
47	-	-	Not Used
48	PK/BK	1746	Fuel Injector Control (3)
49	-	-	Not Used
50	WH/BK	6396	CMP Actuator Solenoid Control Exhaust
51-52	-	-	Not Used
53	OG/WH	2122	Ignition Control (2)
54-55	-	-	Not Used
56	D-GN	5273	CMP Sensor Signal
57-58	-	-	Not Used
59	OG	5275	CMP Sensor Signal
60-61	-	-	Not Used
62	TN	472	Intake Air Temperature Sensor Signal
63	YE	573	Crankshaft Position Sensor Signal
64	D-GN	485	Throttle Position Sensor (1) Signal
65	-	-	Not Used
66	PU	486	Throttle Position Sensor (2) Signal
67	YE	492	Mass Air Flow Sensor Signal
68	GY/WH	3113	Heated Oxygen Sensor Heater Low Control Sensor 1
69	GY/WH	3122	Heated Oxygen Sensor Heater Low Control Sensor 2
70	-	-	Not Used
71	L-BU/BK	844	Fuel Injector (4) Control
72	TN	1744	Fuel Injector (1) Control
73	BK/WH	451	Signal Ground

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Engine Control Module (ECM) Connector End View C2

Use the Manual With the Right Hardware

When to See a Mechanic