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: 34576-3003
  • Service: See Catalog
  • Description: 56-Way F Micro-Pack 64 Series Sealed (BU)

Terminal Part Information

  • Pins: 2, 6, 9, 12, 13, 16, 19, 29, 34, 40, 44, 48, 53, 56
  • Terminal/Tray: 33467-0003/23
  • Core/Insulation Crimp: H/H
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)
  • Pins: 7, 15, 18, 20, 33, 35-37, 47, 49, 54, 55
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: J/J
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)

Engine Control Module (ECM) C1

Pin

Wire Color

Circuit No.

Function

1

--

--

Not Used

2

PU

420

TCC Switch/Cruise Control Release Signal

3-5

--

--

Not Used

6

BN/WH

379

CPP Switch Signal

7

L-BU

20

Stop Lamp Supply Voltage

8

--

--

Not Used

9

BK

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

PU

1807

Class 2 Serial Data

16

PU

1807

Class 2 Serial Data

17

--

--

Not Used

18

BN

4

Accessory Voltage

19

YE

1139

Ignition 1 Voltage

20

OG

480

Battery Positive Voltage

21-28

--

--

Not Used

29

GY

1884

Cruise Control Set/Coast and Resume/Accelerate Signal

30-32

--

--

Not Used

33

WH/BK

1164

5-Volt Reference

34

GY

705

5-Volt Reference

35

PU

1272

5-Volt Reference

36

BN

1271

Low Reference

37

TN

1274

Low Reference

38-39

--

--

Not Used

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 (C60)

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: 1335545  Size: CH

Connector Part Information

  • OEM: 34566-2503
  • Service: 88988360
  • Description: 73-Way F Micro-Pack 64 Series Sealed (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, 14, 17, 20, 23, 27, 30, 33, 35, 36, 39, 43, 46, 50, 53, 56, 59, 63
  • Terminal/Tray: 33467-0003/23
  • Core/Insulation Crimp: H/H
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)
  • Pins: 2-5, 8, 9, 29, 32, 42, 44, 48, 62, 64, 66-69, 71, 72, 11-13
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: Pins 2-5, 8, 9, 29, 32, 42, 44, 48, 62, 64, 66-69, 71, 72 - J/J
  • Core/Insulation Crimp: Pins 11, 11, 12, 12, 13, 13 - 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 Signal (Sensor 1)

3

PU/WH

3110

HO2S High Signal (Sensor 1)

4

PU/WH

1668

HO2S High Signal (Sensor 2)

5

TN/WH

1669

HO2S Low Signal (Sensor 2)

6-7

--

--

Not Used

8

D-BU

496

Knock Sensor Signal

9

GY

1716

Knock Sensor Signal

10

--

--

Not Used

11

YE/GN

581

TAC Motor Control 1 (Early Production)

YE

581

TAC Motor Control 1 (Late Production)

12

YE/GN

582

TAC Motor Control 2 (Early Production)

BN

582

TAC Motor Control 2 (Late Production)

13

YE/OG

5290

Ignition 1 Voltage (Early Production)

PK/BK

5290

Ignition 1 Voltage (Late Production)

14

PK/BK

6395

CMP Actuator Solenoid Control Intake

15-16

--

--

Not Used

17

L-BU

2123

IC 3 Control

18-19

--

--

Not Used

20

GY

5296

Low Reference

21-22

--

--

Not Used

23

TN

5301

Low Reference

24-26

--

--

Not Used

27

PU

574

Low Reference

28

--

--

Not Used

29

BK

2752

Low Reference

30

L-GN

5282

Low Reference

31

--

--

Not Used

32

L-GN/BK

1745

Fuel Injector 2 Control

33

D-GN/WH

2124

IC 4 Control

34

--

--

Not Used

35

BN

2129

Low Reference

36

YE/BK

5297

5-Volt Reference

37-38

--

--

Not Used

39

D-BU

5300

5-Volt Reference

40-41

--

--

Not Used

42

BK

2760

Low Reference

43

L-GN

2867

5-Volt Reference

44

GY

2701

5-Volt Reference

45

--

--

Not Used

46

PU

5284

Low Reference

47

--

--

Not Used

48

PK/BK

1746

Fuel Injector 3 Control

49

--

--

Not Used

50

WH/BK

6396

CMP Actuator Solenoid Control Exhaust

51-52

--

--

Not Used

53

RD/WH

2122

IC 2 Control

54-55

--

--

Not Used

56

D-GN

5273

CMP Sensor Signal

57-58

--

--

Not Used

59

OG

5275

CMP Sensor Signal

60-61

--

--

Not Used

62

TN

472

IAT Sensor Signal

63

YE

573

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

BK/WH

3113

HO2S Heater Low Control (Sensor 1)

69

BK/WH

3122

HO2S Heater Low Control (Sensor 2)

70

--

--

Not Used

71

L-BU/BK

844

Fuel Injector 4 Control

72

BK

1744

Fuel Injector 1 Control

73

BK/WH

451

Ground

Engine Control Module (ECM) C3


Object Number: 1335545  Size: CH

Connector Part Information

  • OEM: 34566-2603
  • Service: 88988361
  • Description: 73-Way F Micro-Pack 64 Series Sealed (GY)

Terminal Part Information

  • Pins: 7, 28, 29, 35, 44, 48, 55, 65-67
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: J/J
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)
  • Pins: 21, 23, 33, 37, 39, 47, 49, 53, 57, 59
  • 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

1-6

--

--

Not Used

7

RD

225

Generator Turn On Signal

8-20

--

--

Not Used

21

BK

2751

Low Reference

22

--

--

Not Used

23

OG/BK

469

Low Reference

24-27

--

--

Not Used

28

BK/WH

1704

Low Reference

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

BK

2761

Low Reference

36

--

--

Not Used

37

GY

2700

5-Volt Reference (C60)

38

--

--

Not Used

39

GY

2704

5-Volt Reference

40-43

--

--

Not Used

44

L-BU/BK

1688

5-Volt Reference

45-46

--

--

Not Used

47

D-GN

1433

PNP/Clutch Start Switch Signal

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/WH

2500

High Speed GMLAN Serial Data Bus +

54

--

--

Not Used

55

YE

410

ECT Sensor Signal

56

--

--

Not Used

57

RD/BK

380

A/C Refrigerant Pressure Sensor Signal (C60)

58

--

--

Not Used

59

L-GN

432

MAP Sensor Signal

60-64

--

--

Not Used

65

TN/BK

231

Oil Pressure Sensor Signal

66

YE

400

VSS Signal High (M86)

67

PU

401

VSS Signal Low (M86)

68-73

--

--

Not Used