Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROL SYSTEM & COMPONENT TESTSCOMPUTERIZED ENGINE CONTROLSPOWERTRAIN CONTROL MODULE (PCM) CONNECTOR TERMINAL IDENTIFICATIONPOWERTRAIN CONTROL MODULE (PCM) - 2.2L

1999 GMC Forward Control 5.7 R, Automatic

Powertrain Control Module (Pcm) - 2.2L

1999 GMC Forward Control 5.7 R, AutomaticSECTION Powertrain Control Module (Pcm) - 2.2L

POWERTRAIN CONTROL MODULE (PCM) - 2.2L ⁽¹⁾

Connector

Terminal No.

Wire Color

Function

C1 (Blue)

1-5

.....

Not Used

C1 (Blue)

ORG/BLK

⁽²⁾ Ground

C1 (Blue)

BRN/WHT

CMP Sensor Signal

C1 (Blue)

PPL/WHT

CKP 7x Reference Signal

C1 (Blue)

.....

Not Used

C1 (Blue)

GRY

Fuel Tank Pressure Sensor Reference Voltage

C1 (Blue)

11-17

.....

Not Used

C1 (Blue)

180

BLK/WHT

PCM Ground

C1 (Blue)

PNK

Ignition Voltage

C1 (Blue)

ORN

Battery Voltage

C1 (Blue)

DK BLU

TP Sensor Signal

C1 (Blue)

22-24

.....

Not Used

C1 (Blue)

ORN

Ignition Control B

C1 (Blue)

WHT

Ignition Control A

C1 (Blue)

.....

Not Used

C1 (Blue)

RED

Transmission Range C Input

C1 (Blue)

BLK/WHT

PRNDL A Input

C1 (Blue)

30-32

.....

Not Used

C1 (Blue)

DK BLU

KS Signal

C1 (Blue)

.....

Not Used

C1 (Blue)

PPL

TCC Brake Switch Input

C1 (Blue)

LT BLU

A/C Request Signal

C1 (Blue)

37-44

.....

Not Used

C1 (Blue)

DK GRN

Fuel Tank Pressure Sensor Signal

C1 (Blue)

YEL/BLK

TFT Sensor Signal

C1 (Blue)

47 & 48

.....

Not Used

C1 (Blue)

RED/BLK

A/C Refrigerant Pressure Sensor Signal

C1 (Blue)

50 & 51

.....

Not Used

C1 (Blue)

BLK

A/C Refrigerant Pressure Sensor Ground

C1 (Blue)

.....

Not Used

C1 (Blue)

YEL

ECT Sensor Signal

C1 (Blue)

PPL

Fuel Level Sensor Input

C1 (Blue)

.....

Not Used

C1 (Blue)

BLK

TP Sensor Ground

C1 (Blue)

YEL

Serial Data (Class II)

C1 (Blue)

DK GRN

Serial Data (Class II)

C1 (Blue)

BLK/WHT

PCM Ground

C1 (Blue)

PNK

IGN 2

C1 (Blue)

LT GRN

MAP Sensor Signal

C1 (Blue)

PPL/WHT

VSS High

C1 (Blue)

64-66

.....

Not Used

C1 (Blue)

DK BLU

Transmission Range B Input

C1 (Blue)

PNK

Transmission Range A Input

C1 (Blue)

YEL

PRNDL B

C1 (Blue)

YEL/BLK

High Resolution Vehicle Speed Output

C1 (Blue)

.....

Not Used

C1 (Blue)

GRY

PRNDL C

C1 (Blue)

WHT

PRNDL P

C1 (Blue)

RED

Generator Terminal L

C1 (Blue)

BLK

Fuel Injector No. 1 Control

C1 (Blue)

LT GRN/BLK

Fuel Injector No. 2 Control

C1 (Blue)

77-80

.....

Not Used

C2 (Red)

1-5

.....

Not Used

C2 (Red)

RED/BLK

Pressure Control Solenoid High Control

C2 (Red)

.....

Not Used

C2 (Red)

DK GRN/WHT

Fuel Pump Relay Control

C2 (Red)

LT BLU/WHT

Pressure Control Solenoid Low Control

C2 (Red)

WHT

Tachometer Output

C2 (Red)

11-13

.....

Not Used

C2 (Red)

BLK/WHT

MAP Sensor Ground

C2 (Red)

.....

Not Used

C2 (Red)

DK GRN/WHT

VSS Output (Cruise)

C2 (Red)

DK GRN

VSS Output (Cluster)

C2 (Red)

18 & 19

.....

Not Used

C2 (Red)

TAN

IAT Sensor Signal

C2 (Red)

TAN

HO2S 1 Low

C2 (Red)

PPL

HO2S 1 Signal

C2 (Red)

TAN/WHT

HO2S 2 Low

C2 (Red)

PPL/WHT

HO2S 2 Signal

C2 (Red)

25 & 26

.....

Not Used

C2 (Red)

BRN

ECT Sensor Ground

C2 (Red)

GRY

IAT Sensor Ground

C2 (Red)

BLK

TFT Sensor Ground

C2 (Red)

.....

Not Used

C2 (Red)

RED/BLK

ICM Reference Low

C2 (Red)

.....

Not Used

C2 (Red)

GRY

TP Sensor Reference Voltage

C2 (Red)

GRY

A/C Refrigerant Pressure Sensor Reference Voltage

C2 (Red)

GRY

MAP Sensor Reference Voltage

C2 (Red)

RED

CMP Sensor Battery Voltage Supply

C2 (Red)

37-45

.....

Not Used

C2 (Red)

BRN/WHT

MIL Control

C2 (Red)

.....

Not Used

C2 (Red)

LT BLU/BLK

Cruise Engaged Input

C2 (Red)

.....

Not Used

C2 (Red)

TAN/BLK

TCC Solenoid Control

C2 (Red)

YEL/BLK

2-3 Shift Solenoid Control

C2 (Red)

WHT

3-2 Shift Solenoid Control

C2 (Red)

LT GRN

1-2 Shift Solenoid Control

C2 (Red)

.....

Not Used

C2 (Red)

DK GRN/WHT

A/C Compressor Clutch Relay Control

C2 (Red)

DK GRN/WHT

EVAP Canister Purge Valve Control

C2 (Red)

BRN

TCC PWM Solenoid Control

C2 (Red)

WHT

EVAP Canister Vent Solenoid Control

C2 (Red)

59-61

.....

Not Used

C2 (Red)

LT GRN/BLK

VSS Low

C2 (Red)

PNK/BLK

CMP Sensor Ground

C2 (Red)

BLK/WHT

PCM Ground

C2 (Red)

65-70

.....

Not Used

C2 (Red)

LT BLU/WHT

IAC Coil A High

C2 (Red)

LT GRN/WHT

IAC Coil B High

C2 (Red)

LT GRN/BLK

IAC Coil B Low

C2 (Red)

LT BLU/BLK

IAC Coil A Low

C2 (Red)

LT BLU/BLK

Fuel Injector No. 4 Control

C2 (Red)

PNK/BLK

Fuel Injector No. 3 Control

C2 (Red)

77-80

.....

Not Used

⁽¹⁾	See Figure.

⁽²⁾	Fuel tank pressure sensor, fuel level sensor and fuel pump grounds.

RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.