For 1990-2009 cars

Connector 1: | Engine Control Module (ECM) C1
Connector 2: | Engine Control Module (ECM) C2
Connector 3: | Engine Control Module (ECM) C3

### Engine Control Module (ECM) C1

#### Connector Part Information

- OEM: 34576-2603
- Service: 88988373
- Description: 56-Way F (GY)

#### Terminal Part Information

- Pins: 6, 9, 13, 19, 20, 34, 44, 48, 55
- Terminal/Tray: 33467-0005/23
- Core/Insulation Crimp: J/J
- Release Tool/Test Probe: J38125-213/J-35616-64B (L-BU)

- Pins: 7, 12, 18, 33, 35-37, 40, 47, 49, 53, 54, 56
- Terminal/Tray: 33467-0003/23
- Core/Insulation Crimp: H/H
- Release Tool/Test Probe: J38125-213/J-35616-64B (L-BU)

#### Engine Control Module (ECM) C1

Pin | Wire Color | Circuit No. | Function
--- | --- | --- | ---
1-5 | -- | -- | Not Used
6 | BN/WH | 379 | CPP Switch Signal (MA5)
7 | L-BU | 20 | Stop Lamp Supply Voltage
8 | -- | -- | Not Used
9 | TN | 2759 | Fuel Tank Pressure Sensor Low Reference
10-11 | -- | -- | Not Used
12 | BN/WH | 419 | MIL Control
13 | D-GN/WH | 465 | Fuel Pump Relay Control
14-17 | -- | -- | Not Used
18 | BN | 4 | Accessory Voltage
19 | PK | 1039 | Ignition 1 Voltage
20 | RD/WH | 840 | Battery Positive Voltage
21-32 | -- | -- | Not Used
33 | WH/BK | 1164 | 5-Volt Reference 2
34 | GY | 2709 | 5-Volt Reference 1
35 | TN | 1274 | 5-Volt Reference 1
36 | BN | 1271 | Low Reference
37 | PU | 1272 | Low Reference
38-39 | -- | -- | Not Used
40 | BN | 5069 | Main Relay Control
41-43 | -- | -- | Not Used
44 | PU | 1589 | Fuel Level Sensor Signal
45-46 | -- | -- | Not Used
47 | D-BU | 1161 | APP Sensor 1 Signal
48 | D-GN | 890 | Fuel Tank Pressure Sensor Signal
49 | L-BU | 1162 | APP Sensor 2 Signal
50-52 | -- | -- | Not Used
53 | D-GN/WH | 459 | A/C Compressor Clutch Relay Control (C60)
54 | D-BU | 473 | High Speed Cooling Fan Relay Control
55 | WH | 1310 | EVAP Canister Vent Solenoid Control
56 | YE | 447 | Starter Relay Coil Control

### Engine Control Module (ECM) C2

#### Connector Part Information

- OEM: 34566-2503
- Service: 88988931
- Description: 73-Way F 0.64 Receptacle 2.8 Series, Sealed (BK)

#### Terminal Part Information

- Pins: 1, 17, 20, 23, 27, 33, 35, 36, 39, 42, 43, 53, 56, 59, 62, 63, 67,
- Terminal/Tray: 33467-0003/23
- Core/Insulation Crimp: H/H
- Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)

- Pins: 2-5, 8, 9, 11-14, 29, 30, 32, 44, 46, 48, 50, 64, 66, 68, 69, 71, 72
- Terminal/Tray: 33467-0005/23
- Core/Insulation Crimp: Pins: 2-5, 8, 9, 14, 29, 30, 32, 44, 46, 48, 50, 64, 66, 68, 69, 71, 72 - J/J
- Core/Insulation Crimp: Pins: 11-13 - K/K
- Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)

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

#### Engine Control Module (ECM) C2

Pin | Wire Color | Circuit No. | Function
--- | --- | --- | ---
1 | PU | 2121 | IC 1 Control
2 | TN/WH | 3111 | Heated Oxygen Sensor Low Signal - Sensor 1
3 | PU/WH | 3110 | Heated Oxygen Sensor Heater Low Control - 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 Available
8 | D-BU | 496 | KS Signal
9 | GY | 1716 | KS Signal
10 | -- | -- | Not Available
11 | YE | 581 | TAC Motor Control - 1
12 | BN | 582 | TAC Motor Control - 2
13 | PK/BK | 5290 | Ignition 1 Voltage
14 | PU | 5284 | Camshaft Phaser Intake Solenoid Control
15-16 | -- | -- | Not Available
17 | L-BU | 2123 | IC 3 Control
18-19 | -- | -- | Not Available
20 | GY | 5296 | Low Reference
21-22 | -- | -- | Not Available
23 | TN | 5301 | Low Reference
24-26 | -- | -- | Not Available
27 | PU | 574 | Low Reference
28 | -- | -- | Not Available
29 | TN | 2752 | Low Reference
30 | L-GN | 5282 | Low Reference
31 | -- | -- | Not Available
32 | GN/BK | 1745 | Fuel Injector 2 Control
33 | D-GN/WH | 2124 | IC 4 Control
34 | -- | -- | Not Available
35 | BN | 2129 | Low Reference
36 | YE/BK | 5297 | 5-Volt Reference 1
37-38 | -- | -- | Not Available
39 | D-BU | 5300 | 5-Volt Reference 1
40-41 | -- | -- | Not Available
42 | BK | 2760 | Low Reference
43 | L-GN | 2867 | 5-Volt Reference 2
44 | GY | 2701 | 5-Volt Reference 2
45 | -- | -- | Not Available
46 | TN | 2199 | Low Reference
47 | -- | -- | Not Available
48 | PK/BK | 1746 | Fuel Injector 3 Control
49 | -- | -- | Not Available
50 | TN | 452 | Camshaft Phaser Exhaust Solenoid Control
51-52 | -- | -- | Not Available
53 | OG/WH | 2122 | IC 2 Control
54-55 | -- | -- | Not Available
56 | D-GN | 5273 | Camshaft Position Exhaust Sensor Signal
57-58 | -- | -- | Not Available
59 | OG | 5275 | Camshaft Position Intake Sensor Signal
60-61 | -- | -- | Not Available
62 | TN | 472 | IAT Sensor Signal
63 | YE | 573 | CKP Sensor Signal
64 | D-GN | 485 | TP Sensor 1 Signal
65 | -- | -- | Not Available
66 | PU | 486 | TP Sensor 2 Signal
67 | YE | 492 | MAF 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 Available
71 | L-BU/BK | 844 | Fuel Injector 4 Control
72 | TN | 1744 | Fuel Injector 1 Control
73 | BK/WH | 451 | Ground

### Engine Control Module (ECM) C3

#### Connector Part Information

- OEM: 34566-2603
- Service: 88988372
- Description: 73-Way F 0.64 Receptacle 2.8 Series, Sealed (GY)

#### Terminal Part Information

- Pins: 7, 21, 23, 28, 29, 35, 37, 39, 44, 46-49, 55, 57, 59, 66, 67
- Terminal/Tray: 33467-0003/23
- Core/Insulation Crimp: H/H
- Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)

- Pins: 33, 53, 65
- Terminal/Tray: 33467-0005/23
- Core/Insulation Crimp: Pins: 33, 53 - J/J Pins: 65 - K/K
- Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)

#### Engine Control Module (ECM) C3

Pin | Wire Color | Circuit No. | Function
--- | --- | --- | ---
1-6 | -- | -- | Not Used
7 | OG | 225 | Generator Turn On Signal
8-20 | -- | -- | Not Used
21 | BK/WH | 2751 | Low Reference (C60)
22 | -- | -- | Not Used
23 | OG/BK | 469 | Low Reference
24-27 | -- | -- | Not Used
28 | TN/WH | 1704 | Low Reference
29 | GY | 23 | Generator Field Duty Cycle Signal
30-32 | -- | -- | Not Used
33 | TN | 2501 | High Speed GMLAN Serial Data (-)
34 | -- | -- | Not Used
35 | TN | 2761 | Low Reference
36 | -- | -- | Not Used
37 | GY | 2700 | 5-Volt Reference 1 (C60)
38 | -- | -- | Not Used
39 | GY | 2704 | 5-Volt Reference 1
40-43 | -- | -- | Not Used
44 | L-BU/BK | 1688 | 5-Volt Reference 2
45 | -- | -- | Not Used
46 | OG/BK | 1786 | Ignition Lock Cylinder Control Actuator (M82)
47 | D-GN | 1433 | PNP/Clutch Start Switch Signal (MA5)
48 | D-GN/WH | 428 | EVAP Canister Purge Solenoid Control
49 | D-GN | 335 | Low Speed Cooling Fan Relay Control
50-52 | -- | -- | Not Used
53 | TN/BK | 2500 | High Speed GMLAN Serial Data (+)
54 | -- | -- | Not Used
55 | YE | 410 | ECT Sensor Signal
56 | -- | -- | Not Used
57 | OG/BK | 380 | A/C Refrigerant Pressure Sensor Signal (C60)
58 | -- | -- | Not Used
59 | L-GN | 432 | MAP Sensor Signal
60-64 | -- | -- | Not Used
65 | TN/BK | 231 | Oil Pressure Switch Signal
66 | YE | 400 | OSS High Signal (MA5)
67 | PU | 401 | OSS Low Signal (MA5)
68-73 | -- | -- | Not Used