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: 1228485  Size: CH

Connector Part Information

  • OEM: 34576-0703
  • Service: 88988373
  • Description: 56-Way F (BU)

Terminal Part Information

  • Pins: 7, 18, 34, 39, 40, 44, 45, 53, 54, 56
  • Terminal/Tray: 33467-0003/23
  • Core/Insulation Crimp: H/H
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)
  • Pins: 9, 12, 13, 20, 33, 35, 36, 37, 46, 47, 48, 49, 19, 55
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: Pins 9, 12, 13, 20, 33, 35, 36, 37, 46, 47, 48, 49 - J/J
  • Core/Insulation Crimp: Pins 19, 55 - K/K
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)

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 (Primary)

14-17

--

--

Not Used

18

YE/BK

5728

ECM/TCM Serial Data Wake Up

19

PK

239

Run/Crank Ignition 1 Voltage

20

RD/WH

1440

Battery Positive Voltage

21-32

--

--

Not Used

33

WH/BK

1164

Accelerator Pedal Position 5-Volt Reference (1)

34

GY

2709

5-Volt Reference

35

TN

1274

5-Volt Reference

36

BN

1271

Low Reference

37

PU

1272

Low Reference

38

--

--

Not Used

39

BN

818

Vehicle Speed Signal

40

BN

5069

Powertrain Relay Control

41-43

--

--

Not Used

44

D-BU

1936

Fuel Level Sensor Signal (Secondary)

45

L-BU

1937

Secondary Fuel Level Sensor Signal

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

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


Object Number: 1650395  Size: CH

Connector Part Information

  • OEM: 34566-0103
  • Service: 88988931
  • Description: 73-Way F (BK)

Terminal Part Information

  • Pins: 73
  • Terminal/Tray: 7116-4152-02/9
  • Core/Insulation Crimp: 2/5
  • Release Tool/Test Probe: 12094430/J-35616-35 (VT)
  • Pins: 13, 28, 45, 65
  • Terminal/Tray: 33467-0003/23
  • Core/Insulation Crimp: H/H
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)
  • Pins: 1, 2, 3, 4, 5, 6, 7, 8, 9, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 62, 63, 64, 66, 67, 68, 69, 70, 71, 72, 11, 12
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: Pins 1, 2, 3, 4, 5, 6, 7, 8, 9, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 62, 63, 64, 66, 67, 68, 69, 70, 71, 72 - J/J
  • Core/Insulation Crimp: Pins 11, 12 - 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

2121

IC 1 Control

2

TN/WH

3111

HO2S Low Reference (Bank 1 Sensor 1)

3

PU/WH

3110

HO2S Reference Voltage (Bank 1 Sensor 1)

4

PU

3120

HO2S Reference Voltage (Bank 1 Sensor 2)

5

TN/WH

3121

HO2S Low Reference (Bank 1 Sensor 2)

6

L-BU

1876

Knock Sensor 2 Signal

7

GY

2303

Knock Sensor 2 Signal

8

D-BU

496

Knock Sensor 1 Signal

9

GY

1716

Knock Sensor 1 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

Camshaft Position (CMP) Actuator Solenoid - Intake Bank 1 Control

15

TN/BK

6397

Camshaft Position (CMP) Actuator Solenoid - Intake Bank 2 Control

16

D-BU/WH

878

Fuel Injector 8 Control

17

OG/WH

2122

IC 2 Control

18

L-BU/WH

2126

IC 6 Control

19

BN/WH

2130

Low Reference

20

PU

6267

Low Reference

21

TN

6268

Low Reference

22

WH

6269

Low Reference

23

BN

6266

Low Reference

24

BK

2755

Low Reference

25-26

--

--

Not Used

27

GY/BK

6272

Low Reference

28

PK/BK

5290

Ignition 1 Voltage

29

TN

2752

Low Reference

30

BN/WH

6754

Low Reference

31

D-BU/WH

6756

Low Reference

32

L-BU/BK

1746

Fuel Injector 3 Control

33

OG

2127

IC 7 Control

34

D-GN

2125

IC 5 Control

35

BN

2129

Low Reference

36

D-GN

6457

5-Volt Reference

37

OG

6260

5-Volt Reference

38

PK

6261

5-Volt Reference

39

D-BU

6259

5-Volt Reference

40

GY

2705

5-Volt Reference

41

--

--

Not Used

42

TN

2760

Low Reference

43

PU/WH

6270

5-Volt Reference

44

GY

2701

5-Volt Reference

45

--

--

Not Used

46

BN

6753

Low Reference

47

D-BU

6755

Low Reference

48

L-GN/BK

1745

Fuel Injector 2 Control

49

TN/WH

845

Fuel Injector 5 Control

50

WH/BK

6396

Camshaft Position (CMP) Actuator Solenoid - Exhaust Bank 1 Control

51

GY/BK

6394

Camshaft Position (CMP) Actuator Solenoid - Exhaust Bank 2 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 5 Control

56

D-GN/WH

6264

Camshaft Position (CMP) Sensor - Exhaust Bank 1 Signal

57

OG/BK

6263

Camshaft Position (CMP) Sensor - Intake Bank 2 Signal

58

PK/BK

6262

Camshaft Position (CMP) Sensor - Exhaust Bank 2 Signal

59

D-BU/WH

6265

Camshaft Position (CMP) Sensor - Intake Bank 1 Signal

60

TN/WH

331

Oil Pressure Sensor Signal

61

--

--

Not Used

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

YE

492

MAF Sensor Signal

68

GY/WH

3113

HO2S Heater Low Control (Bank 1 Sensor 1)

69

GY/WH

3122

HO2S Heater Low Control (Bank 2 Sensor 1)

70

YE/BK

846

Fuel Injector 6 Control

71

OG/BK

877

Fuel Injector 7 Control

72

TN

1744

Fuel Injector 1Control

73

BK/WH

1551

Ground

Engine Control Module (ECM) C3


Object Number: 1650395  Size: CH

Connector Part Information

  • OEM: 34566-0203
  • Service: 88988372
  • Description: 73-Way F (GY)

Terminal Part Information

  • Pins: 73
  • Terminal/Tray: 7116-4152-02/9
  • Core/Insulation Crimp: 2/5
  • Release Tool/Test Probe: 12094430/J-35616-35 (VT)
  • Pins: 3, 4, 5, 6, 7, 14, 15, 16, 18, 21, 22, 23, 29, 33, 34, 35, 37, 38, 39, 46, 50, 53, 55, 56, 57, 58, 59
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: J/J
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)
  • Pins: 48, 49
  • Terminal/Tray: 33467-0003/23
  • Core/Insulation Crimp: H/H
  • 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

PU

3220

HO2S Reference Voltage (Bank 2 Sensor 2)

6

TN

3221

HO2S Low Reference (Bank 2 Sensor 2)

7

OG

225

Generator Turn On Signal

8-14

--

--

Not Used

15

L-GN

3212

HO2S Heater Low Control (Bank 2 Sensor 1)

16-17

--

--

Not Used

18

BN

1174

Oil Level Switch Signal (RHD)

19-20

--

--

Not Used

21

BK/WH

2751

Low Reference

22

--

--

Not Used

23

OG/BK

469

Low Reference

24-28

--

--

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

TN

2761

Low Reference

36

--

--

Not Used

37

GY

2700

5-Volt Reference

38

--

--

Not Used

39

GY

2704

5-Volt Reference

40-45

--

--

Not Used

46

OG/BK

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

OG/WH

3223

HO2S Heater Low Control (Bank 2 Sensor 2)

51-52

--

--

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/BK

380

A/C Refrigerant Pressure Sensor Signal

58

--

--

Not Used

59

L-GN

432

MAP Sensor Signal

60-72

--

--

Not Used

73

BK/WH

1551

Ground