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HOMESERVICE MANUALSCHEVROLET1994SUBURBAN K2500, 5.7 KREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - TESTS W/CODES - ELECTRONIC TRANSMISSIONSELF-DIAGNOSTIC SYSTEMTROUBLE CODE IDENTIFICATION

1994 Chevrolet Suburban K2500, 5.7 K

Trouble Code Identification

1994 Chevrolet Suburban K2500, 5.7 KSECTION Trouble Code Identification

NOTE: Trouble codes retrieved from PCM/TCM may be related to either engine or transmission. Transmission-related codes are covered in this article. For engine-related codes, see appropriate TESTS W/CODES article in the ENGINE PERFORMANCE section. See below. See TROUBLE CODE IDENTIFICATION table to determine if code is transmission or engine related.

The system codes indicate failure of a specific sensor and/or circuit. Sensor/circuit diagnosis may indicate replacement of the control module. Code 51 indicates PROM is installed improperly or has failed.
Code 55 indicates PCM/TCM has failed and must be replaced. If the condition is still not corrected after replacing PCM/TCM, the cause may be as follows.

An incorrect PCM/TCM or PROM application may cause a malfunction, which may or may not set a code.
The PCM/TCM connector may be the problem. Connector terminals may have to be removed from the connector to be properly checked.
PROM failure. Although the PROM rarely fails, it could be the cause of the problem.
Replacement PCM/TCM may be faulty.
Intermittent problem. Make a careful physical inspection of affected sensor/circuit.
A shorted solenoid, relay, or harness may be the cause of PCM/TCM failure. Use Short Circuit Tester (J-34636) to check for short circuits.

TROUBLE CODE IDENTIFICATION

Code

Probable Cause

12 ⁽¹⁾

No Engine Speed Sensor Reference Pulse

13 ⁽¹⁾

Open Oxygen Sensor Circuit

13 ⁽²⁾

Engine Shutoff Solenoid Circuit Fault

14 ⁽¹⁾

CTS Voltage Low (Sensor Or Signal Line Grounded)

14 ⁽²⁾

ECT Sensor Circuit Low (High Temp. Indicated)

15 ⁽¹⁾

CTS Voltage High (Sensor Or Signal Line Open)

15 ⁽²⁾

ECT Sensor Circuit High (Low Temp. Indicated)

16 ⁽¹⁾

VSS Buffer Fault (4.3L)

16 ⁽³⁾

Transmission Output Speed Signal Low

16 ⁽²⁾

Vehicle Speed Sensor Buffer Fault

17 ⁽²⁾

High Resolution Circuit Fault

18 ⁽²⁾

Pump Cam Reference Pulse Error

19 ⁽²⁾

Crankshaft Position Reference Error

21 ⁽¹⁾

TP Sensor Voltage High (Open Ckt Or Misadjusted TP Sensor)

21 ⁽²⁾

Accelerator Pedal Position No. 1 Circuit High

22 ⁽¹⁾

TP Sensor Voltage Low (Circuit Grounded)

22 ⁽²⁾

Accelerator Pedal Position No. 1 Circuit Low

23 ⁽¹⁾

Intake Air Temperature Low

23 ⁽²⁾

Accelerator Pedal Position No. 1 Circuit Range Fault

24 ⁽⁴⁾

Vehicle Speed Sensor Transmission Output Signal

25 ⁽¹⁾

Intake Air Temperature Sensor Voltage Low

25 ⁽²⁾

Accelerator Pedal Position No. 2 Circuit High

26 ⁽²⁾

Accelerator Pedal Position No. 2 Circuit Low

27 ⁽²⁾

Accelerator Pedal Position No. 2 Circuit Range Fault

28 ⁽⁵⁾

Trans. Range Pressure Switch (4L60E/4L80E)

29 ⁽²⁾

Glow Plug Relay Circuit Fault

31 ⁽²⁾

EGR Control Pressure/BARO Sensor Circuit Low (High Vacuum)

32 ⁽¹⁾⁽²⁾

EGR Circuit Error

33 ⁽¹⁾

MAP Voltage High (Circuit Open Or Short To Voltage)

33 ⁽²⁾

EGR Control Pressure/BARO Sensor Circuit High (Low Vacuum)

34 ⁽¹⁾

MAP Voltage Low (Circuit Open Or Short To Ground)

34 ⁽²⁾

Injection Timing Stepper Motor Circuit Fault

35 ⁽¹⁾

IAC System Fault

35 ⁽²⁾

Injection Pulse Width Error (Response Time Short)

36 ⁽²⁾

Injection Pulse Width Error (Response Time Long)

37/38 ⁽⁵⁾

TCC Brake Switch On/Off (4L60E/4L80E)

39 ⁽⁵⁾

TCC Stuck Off (4L80E)

41 ⁽²⁾

Brake Switch Circuit Fault

42 ⁽¹⁾

EST Circuit Fault

42 ⁽²⁾

Fuel Temperature Circuit Low (High Temp. Indicated)

43 ⁽¹⁾

Knock Sensor Circuit Fault

43 ⁽²⁾

Fuel Temperature Circuit High (Low Temp. Indicated)

44 ⁽¹⁾

Lean Exhaust Indicated

44 ⁽²⁾

EGR Pulse Width Error

45 ⁽¹⁾

Rich Exhaust Indicated

45 ⁽²⁾

EGR Vent Error

46 ⁽²⁾

MIL (SERVICE ENGINE SOON) Circuit Fault

47 ⁽²⁾

IAT Sensor Circuit Low (High Temp. Indicated)

48 ⁽²⁾

IAT Sensor Circuit High (Low Temp. Indicated)

49 ⁽²⁾

SERVICE THROTTLE SOON Light Circuit Fault

51 ⁽¹⁾⁽²⁾

PROM Error (Faulty Or Incorrect PROM)

52 ⁽¹⁾

PROM/CALPAC Error (Faulty/Incorrect PROM/CALPAC)

52 ⁽⁵⁾

System Voltage High (4L60E/4L80E)

53 ⁽⁴⁾

System Voltage High

54 ⁽¹⁾

Fuel Pump Circuit Voltage Low

54 ⁽²⁾

PCM Fuel Circuit Error

55 ⁽¹⁾

ECM/PCM/VCM Error

56 ⁽²⁾

Injection Pump Calibration Resistor Error

57 ⁽²⁾

PCM 5-Volt Shorted

58 ⁽⁵⁾

Trans. Fluid Temp. High (4L60E/4L80E)

59 ⁽⁵⁾

Trans. Fluid Temp. Low (4L60E/4L80E)

61 ⁽²⁾

Turbo Boost Sensor Circuit High

62 ⁽²⁾

Turbo Boost Sensor Circuit Low

63 ⁽²⁾

Accelerator Pedal Position No. 3 Circuit High

64 ⁽²⁾

Accelerator Pedal Position No. 3 Circuit Low

63/64 ⁽⁵⁾

BARO Signal High/Low (4L80E)

65 ⁽²⁾

Accelerator Pedal Position No. 3 Circuit Range Fault

66 ⁽⁵⁾

3-2 Control Solenoid Circuit Fault (4L60E)

67 ⁽⁵⁾

TCC Solenoid Circuit Check (4L60E)

68 ⁽⁵⁾

Overdrive Ratio Error (4L80E)

69 ⁽⁵⁾

Torque Converter Clutch Stuck On (4L60E/4L80E)

71 ⁽²⁾

Set/Coast Switch Fault

71 ⁽⁵⁾

Camshaft Sensor Circuit Low (4L80E)

72 ⁽⁵⁾

VSS Circuit Loss (4L60E/4L80E) Transmission Output Signal

73 ⁽⁵⁾

Pressure Control Solenoid (4L60E/4L80E) (Current Error)

74 ⁽⁵⁾

Trans. Input Speed Error (4L80E)

75 ⁽⁵⁾

System Voltage Low (4L60E/4L80E)

76 ⁽²⁾

Resume/Accel Switch Fault

78 ⁽²⁾

Wastegate Solenoid Fault

79 ⁽⁵⁾

Trans. Fluid Temp. High (4L60E/4L80E)

81 ⁽⁵⁾

Trans. 2-3 Error (4L60E/4L80E)

82 ⁽⁵⁾

Trans. 1-2 Error (4L60E/4L80E)

83 ⁽⁵⁾

TCC Solenoid Circuit Fault (4L80E)

84 ⁽²⁾

Accelerator Pedal Position Circuit Fault

85 ⁽⁵⁾

Undefined Gear Ratio (4L80E)

86 ⁽⁵⁾

Low Gear Ratio Error (4L80E)

87 ⁽⁵⁾

High Gear Ratio Error (4L80E)

88 ⁽²⁾

TDC Offset Error

91 ⁽²⁾

Cylinder Balance Fault No. 1 Cylinder

92 ⁽²⁾

Cylinder Balance Fault No. 2 Cylinder

93 ⁽²⁾

Cylinder Balance Fault No. 3 Cylinder

94 ⁽²⁾

Cylinder Balance Fault No. 4 Cylinder

95 ⁽²⁾

Cylinder Balance Fault No. 5 Cylinder

96 ⁽²⁾

Cylinder Balance Fault No. 6 Cylinder

97 ⁽²⁾

Cylinder Balance Fault No. 7 Cylinder

98 ⁽²⁾

Cylinder Balance Fault No. 8 Cylinder

99 ⁽²⁾

Accelerator Pedal Position No. 2 (5-Volt Reference Fault)

P0107 ⁽¹⁾

MAP Signal Voltage Low (4.3L)

P0108 ⁽¹⁾

MAP Signal Voltage High (4.3L)

P0122 ⁽¹⁾

TP Sensor Circuit Signal Voltage Low

P0123 ⁽¹⁾

TP Sensor Circuit Signal Voltage High

P0131 ⁽¹⁾

HO2S Circuit Low Signal Voltage

P0132 ⁽¹⁾

HO2S Circuit High Signal Voltage

P0139 ⁽¹⁾

HO2S Circuit Open (4.3L)

P0171 ⁽¹⁾

Fuel Trim Lean (Lean Exhaust)

P0172 ⁽¹⁾

Fuel Trim Rich (Rich Exhaust)

P0320 ⁽¹⁾

Ignition Control Error (4.3L)

P0321 ⁽¹⁾

Spark Reference Circuit

P0327 ⁽¹⁾

Knock Sensor Circuit Grounded (4.3L)

P0328 ⁽¹⁾

Knock Sensor Circuit Open (4.3L)

P0342 ⁽¹⁾

Cam Signal Circuit

P0400 ⁽¹⁾

EGR Error

P0500 ⁽¹⁾

VSS Error (4.3L)

P1530 ⁽¹⁾

A/C Head Pressure Switch Circuit

P1531 ⁽¹⁾

Low A/C Refrigerant Charge

P1558 ⁽¹⁾

Cruise System Problem

P1561 ⁽¹⁾

Cruise Vent Solenoid Circuit

P1562 ⁽¹⁾

Cruise Vacuum Solenoid Circuit

P1565 ⁽¹⁾

Cruise Servo Position Sensor Circuit

P1567 ⁽¹⁾

Cruise Switches Circuit

P1568 ⁽¹⁾

Cruise System Problem

P1571 ⁽⁵⁾

Traction Control Desired Torque Out Of Range

P1573 ⁽⁵⁾

Traction Control Loss Of ABS/TCS Serial Data

P1599 ⁽¹⁾

Cruise Power Management

P1623 ⁽¹⁾

PROM Error

P1632 ⁽¹⁾

System Voltage High (4.3L)

⁽¹⁾	Gasoline engine code covered in TESTS W/CODES - 4.3L for 4.3L V6 models, TESTS W/CODES - 5.0L for 5.0L V8-equipped models, TESTS W/CODES - 5.7L for models equipped with a 5.7L V8 and for 7.4L V8, see: TESTS W/CODES - 7.4L .

⁽²⁾	Diesel engine code. For diesel code diagnosis, see TESTS W/CODES - 6.5L DIESEL article in this section.

⁽³⁾	Models equipped with 4L60E transmission.

⁽⁴⁾	Common gasoline engine and transmission code covered in appropriate G - GASOLINE TESTS W/ CODES article in the ENGINE PERFORMANCE section. See footnote number 1 above.

⁽⁵⁾	Transmission code covered in this article.

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.