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 MX123 Series Sealed (BK)

Terminal Part Information

  • Pins: 9, 12-13, 15, 18-19, 29, 33-37, 40, 44, 47-49, 53-56
  • Terminal/Tray: 33467-0003/23
  • Core/Insulation Crimp: H/H
  • Release Tool/Test Probe: J-38125-213/J-35616-64A (L-BU)
  • Pins: 7, 20, 39
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: Pins 7, 39 - J/J
  • Core/Insulation Crimp: Pins 20 - K/K
  • Release Tool/Test Probe: J-38125-213/J-35616-64A (L-BU)

Engine Control Module (ECM) C1

Pin

Wire Color

Circuit No.

Function

1-6

--

--

Not Used

7

L-GN

526

Stop Lamp Supply Voltage

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

--

--

Not Used

15

D-GN

1049

Class 2 Serial Data

16-17

--

--

Not Used

18

BN

1141

Accessory Voltage

19

PK

439

Ignition 1 Voltage

20

RD/WH

540

Battery Positive Voltage

21-28

--

--

Not Used

29

GY

1884

Cruise Control Switch Signal

30-32

--

--

Not Used

33

WH/BK

1164

5-Volt Reference

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

D-GN

389

Vehicle Speed Signal

40

BN

5069

Powertrain 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

54

D-BU

473

High Speed Cooling Fan Relay Control

55

WH

1310

EVAP Canister Vent Solenoid Control

56

YE/BK

625

Starter Enable Relay Control

Engine Control Module (ECM) C2


Object Number: 1335545  Size: CH

Connector Part Information

  • OEM: 34566-0103
  • Service: 88988931
  • Description: 73-Way F MX123 Series Sealed (BK)

Terminal Part Information

  • Pins: 1, 10, 14, 17, 23-24, 26-27, 33, 35, 39-40, 42-43, 46, 59-60, 62-63, 67
  • Terminal/Tray: 33467-0003/23
  • Core/Insulation Crimp: H/H
  • Release Tool/Test Probe: J-38125-213/J-35616-64A (L-BU)
  • Pins: 2-9, 11-13, 29, 32, 44, 48-49, 52, 64, 66, 68- 69, 71-72
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: Pins 2-5: K/K
  • Core/Insulation Crimp: Pins 6-9, 11-13, 29, 32, 44, 48-49, 52, 64, 66, 68-69, 71-72: J/J
  • Release Tool/Test Probe: J-38125-213/J-35616-64A (L-BU)
  • Pin: 73
  • Terminal/Tray: 7116-4152-02/9
  • Core/Insulation Crimp: 2/5
  • Release Tool/Test Probe: 12094430/J-35616-4A (PU)

Engine Control Module (ECM) C2

Pin

Wire Color

Circuit No.

Function

1

PU

2121

IC 1 Control

2

TN/WH

3111

HO2S Low Signal - Sensor 1

3

PU/WH

3110

HO2S High Signal - Sensor 1

4

PU

3120

HO2S High Signal - Sensor 2

5

GY

3122

HO2S Low Signal - Sensor 2

6

L-BU

1876

KS 2 Signal

7

GY

2303

KS 2 Signal

8

D-BU

496

KS 1 Signal

9

GY

1716

KS 1 Signal

10

BK/WH

1251

Ground

11

YE

581

TAC Motor Control - 1

12

BN

582

TAC Motor Control - 2

13

PK/BK

5290

Ignition 1 Voltage

14

BN

2198

Camshaft Position Actuator Solenoid High Control

15-16

--

--

Not Used

17

OG/WH

2122

IC 2 Control

18-22

--

--

Not Used

23

TN

407

Low Reference

24

TN

808

Low Reference

25

--

--

Not Used

26

BK/WH

1251

Ground

27

YE/BK

1868

Low Reference

28

--

--

Not Used

29

TN

2752

Low Reference

30-31

--

--

Not Used

32

L-BU/BK

844

Fuel Injector 4 Control

33

L-BU

2123

IC 3 Control

34

--

--

Not Used

35

YE

2174

Low Reference

36-38

--

--

Not Used

39

D-BU

6259

5-Volt Reference

40

GY

605

5-Volt Reference

41

--

--

Not Used

42

TN

2760

Low Reference

43

L-GN

1867

5-Volt Reference

44

GY

2701

5-Volt Reference

45

--

--

Not Used

46

TN

2199

Low Reference

47

--

--

Not Used

48

L-GN/BK

1745

Fuel Injector 2 Control

49

YE/BK

846

Fuel Injector 6 Control

50-51

--

--

Not Used

52

TN/WH

845

Fuel Injector 5 Control

53-58

--

--

Not Used

59

BN/WH

633

CMP Sensor Signal

60

TN/WH

331

Oil Pressure Sensor Signal

61

--

--

Not Used

62

TN

472

IAT Sensor Signal

63

L-BU/WH

1800

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 - Sensor 1

69

TN/WH

3121

HO2S Heater Low Control - Sensor 2

70

--

--

Not Used

71

PK/BK

1746

Fuel Injector 3 Control

72

TN

1744

Fuel Injector 1 Control

73

BK/WH

451

Ground

Engine Control Module (ECM) C3


Object Number: 1335545  Size: CH

Connector Part Information

  • OEM: 34566-0203
  • Service: 88988372
  • Description: 73-Way F MX123 Series Sealed (GY)

Terminal Part Information

  • Pins: 7, 12, 17-18, 21, 23, 29, 32, 35, 37, 39, 46, 48-49, 55, 57, 59, 64, 66
  • Terminal/Tray: 33467-0003/23
  • Core/Insulation Crimp: H/H
  • Release Tool/Test Probe: J-38125-213/J-35616-64A (L-BU)
  • Pins: 33, 53
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: J/J
  • Release Tool/Test Probe: J-38125-213/J-35616-64A (L-BU)

Engine Control Module (ECM) C3

Pin

Wire Color

Circuit No.

Function

1-6

--

--

Not Used

7

OG

225

Generator Turn On Signal

8-11

--

--

Not Used

12

TN/BK

464

Delivered Torque Signal

13-16

--

--

Not Used

17

OG/BK

463

Requested Torque Signal

18

BN

1174

Oil Level Switch Signal

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

30-31

--

--

Not Used

32

OG

6392

IMT Valve Control

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

D-GN

6307

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/BK

380

A/C Refrigerant Pressure Sensor Signal

58

--

--

Not Used

59

L-GN

432

MAP Sensor Signal

60-63

--

--

Not Used

64

YE/BK

6806

IMT Valve Signal

65

--

--

Not Used

66

BN/WH

6354

Output Speed High (Replicated TOSS) Input Signal

67-73

--

--

Not Used