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: 34576-4003
  • Service: 88988373
  • Description: 56-Way F (BU) (Encased in BK)

Terminal Part Information

  • Pins: 11
  • Terminal/Tray: See Terminal Repair Kit
  • Core/Insulation Crimp: See Terminal Repair Kit
  • Release Tool/Test Probe: See Terminal Repair Kit
  • Pins: 1, 6, 7, 12, 14, 15, 16, 18, 20, 25, 29, 33, 35, 36, 37, 39, 40, 47, 49, 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, 34, 44, 45, 48, 19, 55
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: Pins 9, 34, 44, 45, 48 - 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

YE

5

Crank Voltage

2-5

--

--

Not Used

6

BN/WH

379

CCP Switch Signal

7

OG

5371

BAS Relay Coil Supply Voltage

8

--

--

Not Used

9

TN

452

Low Reference

10

--

--

Not Used

11-12

--

--

Not Used

13

D-GN/WH

465

Fuel Pump Relay Control

14

--

--

Not Used

15

PU

1807

Class 2 Serial Data (Primary)

16

PU

1807

Class 2 Serial Data (Primary)

17

--

--

Not Used

18

YE

343

Accessory Voltage

19

PK

239

Ignition Voltage

20

RD/WH

1440

Battery Position Voltage

21-24

--

--

Not Used

25

WH

121

Engine Speed Signal

26-28

--

--

Not Used

29

GY

1884

Cruise Control Switch Signal

30-32

--

--

Not Used

33

WH/BK

1164

5-Volt Reference

34

GY

596

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

Main Relay Control

41-43

--

--

Not Used

44

D-BU

1936

Primary Fuel Level Sensor Signal

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: 1581643  Size: CH

Connector Part Information

  • OEM: 34566-7103
  • Service: 88988931
  • Description: 73-Way F (BK) (Encased in 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: 1, 17, 18, 29, 33, 34, 44, 53, 54, 55, 64, 66
  • Terminal/Tray: 33467-0003/23
  • Core/Insulation Crimp: H/H
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)
  • Pins: 2, 3, 4, 5, 13, 28, 68, 69, 6, 7, 8, 9, 11, 12, 16, 19, 23, 24, 27, 32, 35, 39, 40, 42, 43, 48, 49, 52, 59, 60, 62, 63, 67, 70, 71, 72
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: Pins 2, 3, 4, 5, 13, 28, 68, 69 - K/K
  • Core/Insulation Crimp: Pins 6, 7, 8, 9, 11, 12, 16, 19, 23, 24, 27, 32, 35, 39, 40, 42, 43, 48, 49, 52, 59, 60, 62, 63, 67, 70, 71, 72 - J/J
  • 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

1664

HO2S Low Signal - Bank 1 Sensor 1

3

PU/WH

1665

HO2S High Signal - Bank 1 Sensor 1

4

PU/WH

1668

HO2S High Signal - Bank 1 Sensor 2

5

TN/WH

1669

HO2S Low Signal - Bank 1 Sensor 2

6

L-BU

1876

Knock Sensor Signal 2

7

TN

407

Knock Sensor Signal 2

8

D-BU

496

Knock Sensor Signal 1

9

GY

1716

Knock Sensor Signal 1

10

--

--

Not Used

11

YE

581

TAC Motor Control - 1

12

BN

582

TAC Motor Control - 2

13

PK/BK

5290

Powertrain Main Relay Fused Supply

14-15

--

--

Not Used

16

L-BU/BK

1746

Fuel Injector 3 Control

17

PU/WH

2128

IC 8 Control

18

D-GN/WH

2124

IC 4 Control

19

BN/WH

2130

Low Reference

20-22

--

--

Not Used

23

PK/BK

632

Low Reference

24

BK

2755

Low Reference

25-26

--

--

Not Used

27

YE/BK

1868

Low Reference

28

PK/BK

5290

Powertrain Main Relay Fused Supply

29

TN/WH

1704

Low Reference

30-31

--

--

Not Used

32

L-GN/BK

1745

Fuel Injector 2 Control

33

OG

2127

IC 7 Control

34

D-GN

2125

IC 5 Control

35

BN

2129

Low Reference

36-38

--

--

Not Used

39

OG

631

5-Volt Reference

40

GY

2705

5-Volt Reference

41

--

--

Not Used

42

TN

552

Low Reference

43

L-GN

1867

5-Volt Reference

44

L-BU/WH

1688

5-Volt Reference

45-47

--

--

Not Used

48

D-BU/WH

878

Fuel Injector 7 Control

49

TN/WH

845

Fuel Injector 5 Control

50-51

--

--

Not Used

52

YE/BK

846

Fuel Injector 6 Control

53

OG/WH

2122

IC 2 Control

54

L-BU/WH

2126

IC 6 Control

55

L-BU

2123

IC 3 Control

56-58

--

--

Not Used

59

BN/WH

633

CMP Sensor

60

TN/WH

331

Oil Pressure Sensor Signal

61

--

--

Not Used

62

TN

472

IAT Sensor Signal

63

D-BU/WH

1869

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

BN

2391

HO2S Heater Low Control - Bank 1 Sensor 2

70

L-BU/BK

844

Fuel Injector 4 Control

71

OG/BK

877

Fuel Injector 7 Control

72

TN

1744

Fuel Injector 1 Control

73

BK

750

Ground

Engine Control Module (ECM) - C3


Object Number: 1581643  Size: CH

Connector Part Information

  • OEM: 34566-7003
  • Service: 88988372
  • Description: 73-Way F (D-GY) (Encased in 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: 12, 17, 33, 47, 49, 53
  • Terminal/Tray: 33467-0003/23
  • Core/Insulation Crimp: H/H
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)
  • Pins: 3, 4, 5, 6, 15, 50, 7, 8, 13, 18, 21, 23, 29, 35, 36, 37, 39, 48, 55, 56, 57, 59, 66, 67
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: Pins 3, 4, 5, 6, 15, 50 - K/K
  • Core/Insulation Crimp: Pins 7, 8, 13, 18, 21, 23, 29, 35, 36, 37, 39, 48, 55, 56, 57, 59, 66, 67 - J/J
  • 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

1667

HO2S Low Signal - Bank 2 Sensor 1

4

PU

1666

HO2S High Signal - Bank 2 Sensor 1

5

PU

1670

HO2S High Signal - Bank 2 Sensor 2

6

TN

1671

HO2S Low Signal - Bank 2 Sensor 2

7

OG

225

Generator Turn On Signal

8

L-GN

1652

Reverse Lockout Solenoid Control

9-11

--

--

Not Used

12

TN/BK

464

Delivered Torque Signal

13

GY

587

Skip/Shift Solenoid Control

14

--

--

Not Used

15

L-GN

3212

HO2S Heater Low Control - Bank 2 Sensor 1

16

--

--

Not Used

17

OG/BK

463

Requested Torque Signal

18

BN

1174

Oil Level Switch Signal

19-20

--

--

Not Used

21

TN

5514

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

OG/BK

1057

Low Reference

37

GY

2700

5-Volt Reference

38

--

--

Not Used

39

GY

2704

5-Volt Reference

40-46

--

--

Not Used

47

PU/WH

1035

Starter Relay Coil Supply Voltage

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

YE/BK

1227

TFT Sensor Signal

57

OG/BK

380

A/C Refrigerant Pressure Sensor Signal

58

--

--

Not Used

59

L-GN

432

MAP Sensor Signal

60-65

--

--

Not Used

66

PU/WH

821

VSS High Signal

67

L-GN/BK

822

VSS Low Signal

68-72

--

--

Not Used

73

BK

750

Ground