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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 TESTS W/CODES - 4.3L article in the ENGINE PERFORMANCE section. See TROUBLE CODE IDENTIFICATION table to determine if code is transmission or engine related.
  1. 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.
  2. Code 55 indicates PCM/TCM has failed (except on 3.8L) 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 Engine Shutoff Solenoid Circuit Fault
14 (1) CTS Voltage Low (Sensor Or Signal Line Grounded)
14 ECT Sensor Circuit Low (High Temp. Indicated)
15 (1) CTS Voltage High (Sensor Or Signal Line Open)
15 ECT Sensor Circuit High (Low Temp. Indicated)
16 (1) VSS Buffer Fault (4.3L)
16 (2) Transmission Output Speed Signal Low
16 Vehicle Speed Sensor Buffer Fault
17 High Resolution Circuit Fault
18 Pump Cam Reference Pulse Error
19 Crankshaft Position Reference Error
21 (1) TP Sensor Voltage High (Open Ckt Or Misadjusted TP Sensor)
21 Accelerator Pedal Position No. 1 Circuit High
22 (1) TP Sensor Voltage Low (Circuit Grounded)
22 Accelerator Pedal Position No. 1 Circuit Low
23 (1) Intake Air Temperature Low
23 Accelerator Pedal Position No. 1 Circuit Range Fault
24 (3) Vehicle Speed Sensor Transmission Output Signal
25 (1) Intake Air Temperature Sensor Voltage Low
25 Accelerator Pedal Position No. 2 Circuit High
26 Accelerator Pedal Position No. 2 Circuit Low
27 Accelerator Pedal Position No. 2 Circuit Range Fault
28 (4) Trans. Range Pressure Switch (4L60E/4L80E)
29 Glow Plug Relay Circuit Fault
31 (1) Engine Speed Control Governor (5.7L "G" Van)
31 EGR Control Pressure/BARO Sensor Circuit Low (High Vacuum)
32 (1) EGR Circuit Error
33 (1) MAP Voltage High (Circuit Open Or Short To Voltage)
33 EGR Control Pressure/BARO Sensor Circuit High (Low Vacuum)
34 (1) MAP Voltage Low (Circuit Open Or Short To Ground)
34 Injection Timing Stepper Motor Circuit Fault
35 (1) IAC System Fault
35 Injection Pulse Width Error (Response Time Short)
36 Injection Pulse Width Error (Response Time Long)
37/38 (4) TCC Brake Switch On/Off (4L60E/4L80E)
39 (4) TCC Stuck Off (4L80E)
41 Brake Switch Circuit Fault
42 (1) EST Circuit Fault
42 Fuel Temperature Circuit Low (High Temp. Indicated)
43 (1) Knock Sensor Circuit Fault
43 Fuel Temperature Circuit High (Low Temp. Indicated)
44 (1) Lean Exhaust Indicated
44 EGR Pulse Width Error
45 (1) Rich Exhaust Indicated
45 EGR Vent Error
46 MIL (SERVICE ENGINE SOON) Circuit Fault
47 IAT Sensor Circuit Low (High Temp. Indicated)
48 IAT Sensor Circuit High (Low Temp. Indicated)
49 SERVICE THROTTLE SOON Light Circuit Fault
51 (1) PROM Error (Faulty Or Incorrect PROM)
52 (1) PROM/CALPAC Error (Faulty/Incorrect PROM/CALPAC)
52 (4) System Voltage High (4L60E/4L80E)
53 (3) System Voltage High
54 (1) Fuel Pump Circuit Voltage Low
54 PCM Fuel Circuit Error
55 (1) ECM/PCM/VCM Error
56 Injection Pump Calibration Resistor Error
57 PCM 5-Volt Shorted
58 (4) Trans. Fluid Temp. High (4L60E/4L80E)
59 (4) Trans. Fluid Temp. Low (4L60E/4L80E)
61 Turbo Boost Sensor Circuit High
62 Turbo Boost Sensor Circuit Low
63 Accelerator Pedal Position No. 3 Circuit High
64 Accelerator Pedal Position No. 3 Circuit Low
63/64 (4) BARO Signal High/Low (4L80E)
65 Accelerator Pedal Position No. 3 Circuit Range Fault
66 (4) 3-2 Control Solenoid Circuit Fault (4L60E)
67 (4) TCC Solenoid Circuit Check (4L60E)
68 (4) Overdrive Ratio Error (4L80E)
69 (4) Torque Converter Clutch Stuck On (4L60E/4L80E)
71 Set/Coast Switch Fault
71 (4) Camshaft Sensor Circuit Low (4L80E)
72 (4) VSS Circuit Loss (4L60E/4L80E) Transmission Output Signal
73 (4) Pressure Control Solenoid (4L60E/4L80E) (Current Error)
74 (4) Trans. Input Speed Error (4L80E)
75 (4) System Voltage Low (4L60E/4L80E)
76 Resume/Accel Switch Fault
78 Wastegate Solenoid Fault
79 (4) Trans. Fluid Temp. High (4L60E/4L80E)
81 (4) Trans. 2-3 Error (4L60E/4L80E)
82 (4) Trans. 1-2 Error (4L60E/4L80E)
83 (4) TCC Solenoid Circuit Fault (4L80E)
84 Accelerator Pedal Position Circuit Fault
85 (4) Undefined Gear Ratio (4L80E)
86 (4) Low Gear Ratio Error (4L80E)
87 (4) High Gear Ratio Error (4L80E)
88 TDC Offset Error
91 Cylinder Balance Fault No. 1 Cylinder
92 Cylinder Balance Fault No. 2 Cylinder
93 Cylinder Balance Fault No. 3 Cylinder
94 Cylinder Balance Fault No. 4 Cylinder
95 Cylinder Balance Fault No. 5 Cylinder
96 Cylinder Balance Fault No. 6 Cylinder
97 Cylinder Balance Fault No. 7 Cylinder
98 Cylinder Balance Fault No. 8 Cylinder
99 Accelerator Pedal Position No. 2 (5-Volt Reference Fault)
(1) Gasoline engine code covered in TESTS W/CODES - 4.3L article in this section.
(2) Models equipped with 4L60E transmission.
(3) Common gasoline engine and transmission code covered in TESTS W/CODES - 4.3L article in the ENGINE PERFORMANCE section.
(4) Transmission code covered in this article.
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