GM Service Manual Online
For 1990-2009 cars only
Connector 1: Engine Control Module (ECM) C1
Connector 2: Engine Control Module (ECM) C2

Engine Control Module (ECM) C1


Object Number: 1650395  Size: CH

Connector Part Information

  • OEM: 34566-4403
  • Service: 88988931
  • Description: 73-Way F MX123 Harness Connector Assembly (BK)

Terminal Part Information

  • Pins: 4, 6, 9-13, 16, 18-20, 23, 24, 27-34, 36-38, 41, 47-50, 56-59, 61, 63-72
  • Terminal/Tray: 33467-0003/23
  • Core/Insulation Crimp: Pins 4, 10, 11, 19, 20, 47, 49, 64, 65, 66, 69 - See Terminal Repair Kit
  • Core/Insulation Crimp: Pins 6, 9, 12, 13, 16, 18, 23, 24, 27-34, 36-38, 41, 48, 50, 56-59, 61, 63, 67, 68, 70-72 - H/H
  • 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) C1

Pin

Wire Color

Circuit No.

Function

1-3

--

--

Not Used

4

PU/WH

1035

Starter Relay Coil Supply Voltage

5

--

--

Not Used

6

GY

48

CPP Switch Signal

7-8

--

--

Not Used

9

WH

17

Stop Lamp Switch Signal

10

PU/WH

1668

HO2S High Signal Bank 1 Sensor 2

11

TN/WH

1669

HO2S Low Signal Bank 1 Sensor 2

12

OG/BK

380

A/C Refrigerant Pressure Sensor Signal

13

BK/WH

2751

Low Reference

14-15

--

--

Not Used

16

D-BU

1936

Fuel Level Sensor Signal - Secondary

17

--

--

Not Used

18

YE

43

Accessory Voltage

19

PK

1439

Ignition 1 Voltage

20

RD/WH

2440

Battery Positive Voltage

21-22

--

--

Not Used

23

PU

1272

Low Reference

24

D-GN

890

Fuel Tank Pressure Sensor Signal

25-26

--

--

Not Used

27

TN

2501

ECM High Speed GMLAN Serial Data Bus -

28

TN/BK

2500

ECM High Speed GMLAN Serial Data Bus +

29

D-BU

1161

APP Sensor 1 Signal

30

BN

1271

Low Reference

31

TN

2759

Low Reference

32

L-BU

1162

APP Sensor 2 Signal

33

GY

2709

5-Volt Reference 1

34

GY

2700

5-Volt Reference 1

35

--

--

Not Used

36

TN

1274

5-Volt Reference 1

37

TN

472

IAT Sensor Signal

38

TN

2760

Low Reference

39-40

--

--

Not Used

41

YE

492

MAF Sensor Signal

42-46

--

--

Not Used

47

PK

439

Ignition 1 Voltage

48

WH

121

Engine Speed Signal

49

TN

1671

HO2S Low Signal Bank 2 Sensor 2

50

D-GN/WH

465

Fuel Pump Relay Control

51-55

--

--

Not Used

56

WH/BK

1164

5-Volt Reference 2

57

D-GN/WH

817

Vehicle Speed Signal

58

D-GN

335

Cooling Fan Relay Control

59

WH/BK

448

Ignition 1 Relay Control

60

--

--

Not Used

61

WH

1310

EVAP Canister Vent Solenoid Control

62

--

--

Not Used

63

D-GN/WH

459

A/C Compressor Clutch Relay Control

64

OG/WH

3223

HO2S Heater Low Control Bank 2 Sensor 2

65

BN

2391

HO2S Heater Low Control Bank 1 Sensor 2

66

GY

587

Skip/Shift Solenoid Control

67

YE/BK

625

Starter Enable Relay Control

68

BN/WH

419

MIL Control

69

PU

1670

HO2S High Signal Bank 2 Sensor 2

70

L-BU

1937

Fuel Level Sensor Signal - Right

71

YE

400

VSS High Signal

72

PU

401

VSS Low Signal

73

BK/WH

451

Ground

Engine Control Module (ECM) C2


Object Number: 1650398  Size: CH

Connector Part Information

  • OEM: 34566-4503
  • Service: 19115670
  • Description: 80-Way F MX123 Harness Connector Assembly (GY)

Terminal Part Information

  • Pins: 2, 3, 5, 6, 8, 11-13, 17-24, 26, 27, 29, 30, 32, 34, 35, 37-41, 43, 44, 50, 53, 56-60, 61, 63-66, 68-79
  • Terminal/Tray: 33467-0003/23
  • Core/Insulation Crimp: Pins 2, 3, 21-24, 26, 27, 29, 30, 32, 34, 35, 41, 43, 44, 50, 53, 58, 61, 63-66, 68, 69 - H/H
  • Core/Insulation Crimp: Pins 5, 6, 8, 11-13, 17-20, 37-40, 56, 57, 59, 60, 70-79 - See Terminal Repair Kit
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)

Engine Control Module (ECM) C2

Pin

Wire Color

Circuit No.

Function

1

--

--

Not Used

2

L-GN

1867

5-Volt Reference 2

3

L-BU/BK

1688

5-Volt Reference 2

4

--

--

Not Used

5

BN

582

TAC Motor Control - 2

6

YE

581

TAC Motor Control - 1

7

--

--

Not Used

8

D-GN/WH

428

EVAP Canister Purge Solenoid Valve Control

9-10

--

--

Not Used

11

L-GN

1652

Reverse Lockout Solenoid Control

12

GY/WH

3113

HO2S Heater Low Control Bank 1 Sensor 1

13

L-GN

3212

HO2S Heater Low Control Bank 2 Sensor 1

14-16

--

--

Not Used

17

D-BU/WH

878

Fuel Injector 8 Control

18

TN/WH

845

Fuel Injector 5 Control

19

YE/BK

846

Fuel Injector 6 Control

20

TN

1744

Fuel Injector 1 Control

21

YE

410

ECT Sensor Signal

22

TN

2761

Low Reference

23

TN/WH

585

Transmission Fluid Temperature Sensor Signal

24

OG/BK

586

Transmission Fluid Temperature Sensor Low Reference

25

--

--

Not Used

26

D-BU

496

KS 1 Signal

27

GY

1716

KS 1 Signal

28

--

--

Not Used

29

L-BU

1876

KS 2 Signal

30

GY

2303

KS 2 Signal

31

--

--

Not Used

32

GY

23

Generator Field Duty Cycle Signal

33

--

--

Not Used

34

BK

2755

Low Reference

35

TN/WH

1704

Low Reference

36

--

--

Not Used

37

L-GN/BK

1745

Fuel Injector 2 Control

38

PK/BK

1746

Fuel Injector 3 Control

39

L-BU/BK

844

Fuel Injector 4 Control

40

OG/BK

877

Fuel Injector 7 Control

41

GY

2705

5-Volt Reference 1

42

--

--

Not Used

43

GY

2704

5-Volt Reference 1

44

OG

631

5-Volt Reference 1

45-49

--

--

Not Used

50

TN/WH

331

Oil Pressure Sensor Signal

51-52

--

--

Not Used

53

OG/BK

469

Low Reference

54-55

--

--

Not Used

56

TN

1664

HO2S Low Signal Bank 1 Sensor 1

57

PU/WH

1665

HO2S High Signal Bank 1 Sensor 1

58

L-GN

432

MAP Sensor Signal

59

PU

1666

HO2S High Signal Bank 2 Sensor 1

60

TN

1667

HO2S Low Signal Bank 2 Sensor 1

61

OG

225

Generator Turn On Signal

62

--

--

Not Used

63

PU

486

TP Sensor 2 Signal

64

BN/WH

633

CMP Sensor Signal

65

D-GN

485

TP Sensor 1 Signal

66

PK/BK

632

Low Reference

67

--

--

Not Used

68

D-BU/WH

1869

CKP Sensor Signal

69

YE/BK

1868

Low Reference

70

PU

2121

IC 1 Control

71

PU/WH

2128

IC 8 Control

72

OG

2127

IC 7 Control

73

OG/WH

2122

IC 2 Control

74

L-BU/WH

2126

IC 6 Control

75

D-GN

2125

IC 5 Control

76

D-GN

2124

IC 4 Control

77

L-BU

2123

IC 3 Control

78

BN

2129

Low Reference

79

BN/WH

2130

Low Reference

80

--

--

Not Used