GM Service Manual Online
For 1990-2009 cars only
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


Object Number: 784851  Size: CH

Connector Part Information

  • OEM: 34576-2803
  • Service: 88988373
  • Description: 56-Way F (BU)

Terminal Part Information

  • Pins: 7, 9, 12, 13, 18, 19, 26, 33, 34, 35, 36, 37, 40, 44, 47, 48, 49, 51, 53, 54, 55
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: J/J
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)
  • Pins: 20
  • Terminal/Tray: See Terminal Repair Kit
  • Core/Insulation Crimp: See Terminal Repair Kit
  • Release Tool/Test Probe: See Terminal Repair Kit

Engine Control Module (ECM) C1

Pin

Wire Color

Circuit No.

Function

1-6

--

--

Not Used

7

WH

17

Stop Lamp Switch Signal

8

--

--

Not Used

9

TN

2759

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

D-BU

5985

Accessory Wake up Serial Data

19

PK

439

Ignition 1 Voltage

20

RD/WH

4640

Battery Positive Voltage

21-25

--

--

Not Used

26

YE

447

Starter Relay Coil Control

27-32

--

--

Not Used

33

WH/BK

1164

5-Volt Reference 2

34

GY

416

5-Volt Reference 1

35

TN/BK

1274

5-Volt Reference 1

36

BN

1271

Low Reference

37

PU/WH

1272

Low Reference

38-39

--

--

Not Used

40

OG/WH

5069

PWR/TRAIN Relay Control

41-43

--

--

Not Used

44

PU/BK

1589

Primary Fuel Level Sensor Signal

45-46

--

--

Not Used

47

D-BU/WH

1161

APP Sensor 1 Signal

48

D-GN

890

Fuel Tank Pressure Sensor Signal

49

L-BU

1162

APP Sensor 2 Signal

50

--

--

Not Used

51

PU

421

Air Solenoid Relay Control

52

--

--

Not Used

53

D-GN/WH

459

A/C Compressor Clutch Relay Control

54

OG

473

High Speed Cooling Fan Relay Control

55

TN/WH

1310

EVAP Canister Vent Solenoid Control

56

--

--

Not Used

Engine Control Module (ECM) C2


Object Number: 1673472  Size: CH

Connector Part Information

  • OEM: 34566-2903
  • Service: 88988931
  • Description: 73-Way F (BK)

Terminal Part Information

  • Pins: 24
  • 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)
  • Pins: 1, 2, 3, 4, 5, 6, 7, 8, 9, 16, 17, 18, 19, 23, 25, 27, 29, 31, 32, 33, 34, 35, 39, 41, 42, 43, 44, 48, 49, 51, 52, 53, 54, 55, 59, 61, 62, 63, 64, 66, 67, 70, 71, 72, 11, 12, 13, 68, 69
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: Pins 1, 2, 3, 4, 5, 6, 7, 8, 9, 16, 17, 18, 19, 23, 25, 27, 29, 31, 32, 33, 34, 35, 39, 41, 42, 43, 44, 48, 49, 51, 52, 53, 54, 55, 59, 61, 62, 63, 64, 66, 67, 70, 71, 72 - J/J
  • Core/Insulation Crimp: Pins 11, 12, 13, 68, 69 - K/K
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)

Engine Control Module (ECM) C2

Pin

Wire Color

Circuit No.

Function

1

PU/BK

2121

IC 1 Control

2

TN/OG

3111

HO2S Low Reference Bank 1 Sensor 1

3

D-GN

3110

HO2S Reference Voltage Bank 1 Sensor 1

4

PK/OG

3120

HO2S 2 Reference Voltage

5

TN/PK

3121

HO2S 2 Low Reference

6

PK/YE

1876

Knock Sensor 2 Signal

7

GY

2303

Knock Sensor 2 Signal

8

D-BU

496

Knock Sensor 1 Signal

9

WH/GY

1716

Knock Sensor 1 Signal

10

--

--

Not Used

11

YE

581

TAC Motor Control - 1

12

OG/PK

582

TAC Motor Control - 2

13

PK/BK

5290

Ignition 1 Voltage

14-15

--

--

Not Used

16

RD/BK

878

Fuel Injector 8 Control

17

RD/WH

2122

IC 2 Control

18

L-BU/WH

2126

IC 6 Control

19

BN/WH

2130

Low Reference

20-22

--

--

Not Used

23

BN

6266

Low Reference

24

--

--

Not Used

25

TN/D-GN

2753

Low Reference

26

--

--

Not Used

27

GY/BK

6272

Low Reference

28

--

--

Not Used

29

RD/YE

2752

Low Reference

30

--

--

Not Used

31

GY

435

EGR Solenoid Low Control

32

PK

1746

Fuel Injector 3 Control

33

OG

2127

IC 7 Control

34

D-GN

2125

IC 5 Control

35

BN

2129

Low Reference

36-38

--

--

Not Used

39

PK/WH

6259

5-Volt Reference 2

40

--

--

Not Used

41

PK/TN

2702

5-Volt Reference 1

42

TN/D-BU

2760

Low Reference

43

RD/GY

6270

CKP Sensor 5-Volt Reference 2

44

PK/RD

2701

5-Volt Reference 2

45-47

--

--

Not Used

48

L-GN/BK

1745

Fuel Injector 2 Control

49

TN/WH

845

Fuel Injector 5 Control

50

--

--

Not Used

51

RD/L-BU

1676

EGR Solenoid High Control

52

L-BU/BK

844

Fuel Injector 4 Control

53

L-BU

2123

IC 3 Control

54

D-GN/WH

2124

IC 4 Control

55

PU/WH

2128

IC 8 Control

56-58

--

--

Not Used

59

D-BU/WH

6265

CMP Sensor Signal

60

--

--

Not Used

61

L-GN/RD

1456

EGR Valve Position Signal

62

TN

472

IAT Sensor Signal

63

WH/BK

6271

CKP Sensor Signal

64

D-GN

485

TP Sensor 1 Signal

65

--

--

Not Used

66

PU

486

TP Sensor 2 Signal

67

TN/YE

492

MAF Sensor Signal

68

WH

3113

HO2S Heater Low Control Bank 1 Sensor 1

69

GY/WH

3122

HO2S 2 Heater Low Control

70

YE/BK

846

Fuel Injector 6 Control

71

OG/BK

877

Fuel Injector 7 Control

72

TN/BK

1744

Fuel Injector 1 Control

73

BK/WH

1551

Ground

Engine Control Module (ECM) C3


Object Number: 1590596  Size: CH

Connector Part Information

  • OEM: 34566-3103
  • Service: 88988372
  • Description: 73-Way F (GY)

Terminal Part Information

  • Pins: 3, 4, 7, 8, 9, 18, 21, 23, 26, 29, 33, 35, 37, 39, 42, 46, 48, 49, 53, 55, 57, 59, 62, 65, 15
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: Pins 3, 4, 7, 8, 9, 18, 21, 23, 26, 29, 33, 35, 37, 39, 42, 46, 48, 49, 53, 55, 57, 59, 62, 65 - J/J
  • Core/Insulation Crimp: Pins 15 - 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

1-2

--

--

Not Used

3

TN/WH

3211

HO2S Low Reference Bank 2 Sensor 1

4

PU/WH

3210

HO2S Reference Voltage Bank 2 Sensor 1

5-6

--

--

Not Used

7

OG

225

Generator Turn On Signal

8

L-GN

1652

Reverse Lockout Solenoid Control

9

WH/BK

436

AIR Pump Relay Control

10-14

--

--

Not Used

15

L-GN/WH

3112

HO2S Heater Low Control Bank 2 Sensor 1

16-20

--

--

Not Used

21

L-BU

5514

Low Reference

22

--

--

Not Used

23

OG/BK

469

Low Reference

24-25

--

--

Not Used

26

WH/GY

6786

Low Reference

27-28

--

--

Not Used

29

GY

23

Generator Field Duty Cycle Signal

30-32

--

--

Not Used

33

TN

2501

High Speed GMLAN Serial Data Bus -

34

--

--

Not Used

35

PK

2761

Low Reference

36

--

--

Not Used

37

GY/BK

2700

5-Volt Reference 1

38

--

--

Not Used

39

GY/WH

2704

5-Volt Reference 1

40-41

--

--

Not Used

42

BN/WH

6790

5-Volt Reference

43-45

--

--

Not Used

46

GY/OG

1786

Park/Neutral Signal

47

--

--

Not Used

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 Bus +

54

--

--

Not Used

55

YE

410

ECT Sensor Signal

56

--

--

Not Used

57

OG/WH

380

A/C Refrigerant Pressure Sensor Signal

58

--

--

Not Used

59

L-GN/BK

432

MAP Sensor Signal

60-61

--

--

Not Used

62

YE/GY

6788

Air Injection Position Signal

63-64

--

--

Not Used

65

YE/D-GN

231

Oil Pressure Switch Signal

66-73

--

--

Not Used