THE CODE DIRECTORY

Diagnostic code references — Page 64.

Browse canonical reference entries. Each definition keeps its own source and vehicle-applicability limits.

Buick / Cadillac +4

P1637

These are code references, not a list of confirmed faults on every vehicle. Read the source and applicability notes, then match the exact vehicle, year, engine and scan report.

Generator L-Terminal Circuit

CAN Link ECM ABS Control Module Circuit Network

Data Bus Powertrain Missing Message From Central Electronic Control

Throttle Valve Position Control Throttle Stuck Temporarily

Generator F-Terminal Circuit

CAN Link ECM INSTM Circuit Network

Data Bus Powertrain Missing Message From Clutch Control

Throttle Valve Position Control Throttle Stuck Permanently

5 Volt Reference 2 Circuit

Vehicle ID Block Corrupted or Not Programmed

Accelerator Pedal Position Sensor 1/2 Range Performance

Internal Control Module ROM RAM Error

Driver 1 Input High Voltage

Powertrain DTCs Available in Another Module

Internal Control Module EEPROM Error

FC Relay 1 Control Circuit

Fuel Pump Primary Circuit Failure

Fuel Pump Primary Circuit

Check DTC Memory Of Air Condition ECU

FC Relay 2 And 3 Control Circuit

Fuel Pump Monitor Circuit High Input

CAN Link Circuit

Check DTC Memory Of Airbag ECU

Engine Speed Output Circuit

Fuel Pump Monitor Circuit Low Input

CAN Link Engine Control Module Transmission Control Module Circuit Network

Check DTC Memory Of Central ECU

TP Output Circuit

Fuel Pump Speed Control Circuit Malfunction

Check DTC Memory Of Clutch ECU

EVAP Solenoid Output Circuit

Body ECU Malfunction

Fuel Pump Resistor Switch Circuit

Data Bus Powertrain Defect

Driver 1 Line 6

Linear O2 Sensor Control Chip Bank 1

Check DTC Memory Of All Wheel Drive ECU

Driver 1 Line 7

Linear O2 Sensor Control Chip Bank 2

Check Coding Of ECUs In Data Bus Powertrain

Knock Sensor Input Chip

Data Bus Powertrain Malfunction

Fuel Injection Pump Module

Data Bus Powertrain Missing Message From Brake Controller

Driver 2 Input High Voltage

Power Steering Pressure Switch Out of Self-Test Range

Power Steering Pressure Switch Out Of Range Fault

Data Bus Powertrain Missing Message From Instrument Panel ECU

Fan 1 Relay Control Circuit

Power Steering Pressure Switch Input Fault

Power Steering Pressure Switch Circuit

Data Bus Powertrain Missing Messages

Powertrain Induced Chassis Pitch Output Circuit

Power Steering Pressure Switch Circuit

Idle Air Control Valve Control Circuit

Check DTC Memory Of Transmissions ECU

Oil Level Lamp Control Circuit

Check DTC Memory Of Brake ECU

Service Throttle Soon Lamp Control Circuit

Check DTC Memory Of Control Panel ECU

EVAP Purge Solenoid Control Circuit

TMA or TMB Signal Line Fault

Unused Power Stage 'B'

Check DTC Memory Of Distance Control ECU

Driver 2 Line 6

CAN Link PCM PCM Circuit Network

Intake CMP Actuator Solenoid Control Circuit

Automatic Transmission System Malfunction

OCV Circuit Malfunction Bank 1

OCV Circuit

A/C Clutch Relays Circuit Short To Ground

1-4 Upshift Solenoid Control Circuit

CAN Link Chip Malfunction

A/C Clutch Relays Circuit Short To B+

Starter Enable Relay Control Circuit

Wastegate Valve Control Circuit

Data Bus Powertrain Range Performance From Distance Control

Cooling Fans Control Circuit

Output Circuit Check Signal High

A/T FI Data Line Failure