Avalanche, Sierra, Silverado, C&K Series, 1999-2005

5.3L V8 VIN Z Auto 4

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Trouble Code: P0752



A/T 1-2 Shift Solenoid - No 2nd Or 3rd Gear (4L60-E, 4L80-E)

Possible Causes:



ATF is burnt or contaminated, or the level is incorrect
 
Transmission has an internal damage to the torque converter
 
Shift solenoid valve seals are damaged or leaking
 
Transmission has failed
 

Trouble Code: P0753



A/T 1-2 Shift Solenoid Circuit Malfunction (4L60-E, 4L80-E)

Possible Causes:



1-2 shift solenoid control circuit is open or shorted to ground
 
1-2 shift solenoid control circuit is shorted to system power
 
1-2 shift solenoid is damaged or has failed
 
PCM has failed
 
TSB 01-07-30-002C contains a repair procedure for this code
 

Trouble Code: P0756



2-3 Shift Solenoid - No 2nd Or 3rd Gear (4L60-E, 4L65-E)

Possible Causes:



ATF is burnt or contaminated
 
Transmission has plugged or restricted fluid circuits
 
Shift solenoid valve seals are leaking or damaged
 
Transmission has failed
 
TSB 01-07-30-036A contains a repair procedure for this code
 

Trouble Code: P0758



A/T 2-3 Shift Solenoid Circuit Malfunction (4L60-E, 4L80-E)

Possible Causes:



2-3 shift solenoid control circuit is open or shorted to ground
 
2-3 shift solenoid control circuit is shorted to system power
 
2-3 shift solenoid power circuit is open (test the TRANS fuse)
 
2-3 shift solenoid is damaged or has failed
 
PCM has failed
 
TSB 01-07-30-002C contains a repair procedure for this code
 

Trouble Code: P0785



A/T 3-2 Shift Solenoid Circuit Malfunction (4L60-E)

Possible Causes:



3-2 shift solenoid control circuit is open, shorted to ground or shorted to system power
 
3-2 shift solenoid power circuit is open (check the TRANS fuse)
 
3-2 shift solenoid is damaged or has failed
 
PCM has failed
 
TSB 01-07-30-002C contains a repair procedure for this code
 

Trouble Code: P1020



Camshaft Phasing System Malfunction

Possible Causes:



AF fuel mode relay circuit (odd bank, even bank) is open
 
AF enable circuit is open or shorted to ground
 
FICM is damaged or it has failed
 

Trouble Code: P1021



CNG Fuel Injector 1 Circuit Malfunction

Possible Causes:



CNG fuel injector 1 control circuit is open or shorted to ground
 
CNG fuel injector 1 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1022



CNG Fuel Injector 2 Circuit Malfunction

Possible Causes:



CNG fuel injector 2 control circuit is open or shorted to ground
 
CNG fuel injector 2 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1023



CNG Fuel Injector 3 Circuit Malfunction

Possible Causes:



CNG fuel injector 3 control circuit is open or shorted to ground
 
CNG fuel injector 3 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1024



CNG Fuel Injector 4 Circuit Malfunction

Possible Causes:



CNG fuel injector 4 control circuit is open or shorted to ground
 
CNG fuel injector 4 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1025



CNG Fuel Injector 5 Circuit Malfunction

Possible Causes:



CNG fuel injector 5 control circuit is open or shorted to ground
 
CNG fuel injector 5 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1026



CNG Fuel Injector 6 Circuit Malfunction

Possible Causes:



CNG fuel injector 6 control circuit is open or shorted to ground
 
CNG fuel injector 6 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1027



CNG Fuel Injector 7 Circuit Malfunction

Possible Causes:



CNG fuel injector 7 control circuit is open or shorted to ground
 
CNG fuel injector 7 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1028



CNG Fuel Injector 8 Circuit Malfunction

Possible Causes:



CNG fuel injector 8 control circuit is open or shorted to ground
 
CNG fuel injector 8 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1106



MAP Sensor Circuit Intermittent High Input

Possible Causes:



MAP sensor signal circuit is shorted to VREF (intermittent fault)
 
MAP sensor ground circuit is open (intermittent fault)
 
MAP sensor is damaged or has failed
 
PCM has failed
 

Trouble Code: P1107



MAP Sensor Circuit Intermittent Low Input

Possible Causes:



MAP sensor signal circuit is shorted to VREF (intermittent fault)
 
MAP sensor ground circuit is open (intermittent fault)
 
MAP sensor is damaged or has failed
 
PCM has failed
 

Trouble Code: P1111



IAT Sensor Circuit Intermittent High Input

Possible Causes:



IAT sensor signal circuit is open (intermittent fault)
 
IAT sensor ground circuit is open (intermittent fault)
 
IAT sensor is damaged (an intermittent "open" condition)
 
PCM has failed
 

Trouble Code: P1112



IAT Sensor Circuit Intermittent Low Input

Possible Causes:



IAT sensor signal circuit is open (intermittent fault)
 
IAT sensor ground circuit is open (intermittent fault)
 
IAT sensor is damaged (an intermittent "open" condition)
 
PCM has failed
 

Trouble Code: P1114



ECT Sensor Circuit Intermittent Low Input

Possible Causes:



ECT sensor signal circuit shorted to ground (intermittent fault)
 
ECT sensor has failed (possible intermittent shorted condition)
 
PCM has failed
 

Trouble Code: P1115



ECT Sensor Circuit Intermittent High Input

Possible Causes:



ECT sensor signal circuit is open between the sensor and PCM
 
ECT sensor ground circuit is open between sensor and PCM
 
ECT sensor has failed (possible intermittent "open" condition)
 
PCM has failed
 

Trouble Code: P1122



TP Sensor Circuit Intermittent High Input

Possible Causes:



TP sensor signal circuit is shorted to VREF (intermittent fault)
 
TP sensor ground circuit is open (an intermittent fault)
 
TP sensor is damaged or has failed (possible intermittent open)
 
PCM has failed
 

Trouble Code: P1125



Accelerator Pedal Position System Malfunction

Possible Causes:



APP sensor connector contaminated with oil or moisture (this condition can cause signal "tracking" between the circuits)
 
When the TAC module detects a fault within the TAC system, it may set more than one code. This is due to the redundant tests run continuously on this system. Locating and repairing a single fault may correct more than one code. Keep this in mind as you review the Captured Info available with a Scan Tool.
 
Refer to the related TAC System trouble codes
 

Trouble Code: P1133



HO2S-11 (Bank 1 Sensor 1) Insufficient Switching

Possible Causes:



Air leaks present in the exhaust manifold or the exhaust pipes
 
Fuel pressure is too high (i.e., causing a rich air fuel mixture)
 
HO2S may be contaminated (due to improper fuel or silicone)
 
HO2S signal high or low reference circuit has high resistance
 
HO2S heater element has failed, or the heater circuit is open
 
PCM has failed
 

Trouble Code: P1153



HO2S-21 (Bank 2 Sensor 1) Insufficient Switching

Possible Causes:



Air leaks present in the exhaust manifold or the exhaust pipes
 
Fuel pressure is too high (i.e., causing a rich air fuel mixture)
 
HO2S may be contaminated (due to improper fuel or silicone)
 
HO2S signal high or low reference circuit has high resistance
 
HO2S heater element has failed, or the heater circuit is open
 
PCM has failed
 

Trouble Code: P1172



Secondary Fuel Pump Insufficient/No Fuel Flow

Possible Causes:



Fuel tank level is too low (must be within 25-75% to test relay)
 
Secondary F/P relay power circuit is open (test the ENG1 fuse)
 
Secondary F/P relay control circuit is open, shorted to ground or shorted to power
 
Secondary F/P relay is damaged or has failed
 
PCM has failed
 

Trouble Code: P1201



Gas Mass Sensor Range/Performance

Possible Causes:



Air filter or air inlet duct is clogged or restricted
 
Air leaks in the exhaust pipes or manifold, or the HO2S location
 
Base engine problem (i.e., engine compression, vacuum leak)
 
CNG system fuel pressure is incorrect
 
PCV system problem (i.e., PCV vacuum hose or valve leaking)
 
EVAP canister purge system malfunction
 
Gasoline contaminated engine oil
 
Fuel pressure regulator damage or leaking
 
PCM has failed
 

Trouble Code: P1207



FICM PWM Signal To PCM Circuit Malfunction

Possible Causes:



FICM sensor PWM signal circuit is open or shorted to ground
 
FICM is damaged or it has failed
 
PCM has failed
 

Trouble Code: P1215



High Pressure Or Low Pressure Lockout, MIL, NGO Circuit Malfunction

Possible Causes:



Natural Gas Output Enable, High Pressure Lockout, Low Pressure Lockout or MIL control circuit is open, shorted to ground or shorted to system power
 
Alternative Fuels ECU is damaged or has failed
 

Trouble Code: P1336



CKP Sensor System Variation Not Learned

Possible Causes:



Set the parking brake and block the drive wheels for safety.
 
Verify the hood is closed.
 
Read the trouble codes. If a code is set, refer to that code.
 
Start the engine. Allow engine temperature to reach at least 158ºF (70ºC). Then key off.
 
Select Crankshaft Position Variation Learn procedure on Scan Tool & start the vehicle.
 
Apply the brake pedal firmly and verify the selector is in Park.
 
Increase accelerator pedal position until fuel cutoff is reached at the test rpm (e.g., 5150). Quickly release the accelerator pedal after fuel cutoff is reached. The CKP system variation compensating values are learned when the engine speed (rpm) decreases back to idle speed and the procedure terminates.
 
Read the trouble codes and recheck for DTC P1336.
 
If DTC P1336 runs and passes, the CKP system variation "learn" procedure is complete. If not, look for other codes. If no codes are set, repeat the test procedure.
 

Trouble Code: P1380



Misfire Detected, Rough Road Data Not Available

Possible Causes:



Use the Freeze Frame/Failure Records data to help find the cause on an intermittent fault. If the code cannot be duplicated, the data in the Freeze Frame/Failure Records can determine how many miles since the code set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass or a fail. Operate the vehicle within the Freeze Frame conditions (i.e., load, engine and vehicle speed, temperature etc.). This will isolate when the code set.
 
Service the ABS before diagnosing a misfire because an actual engine misfire may or may not exist. Also, an actual engine misfire may have occurred during an ABS malfunction.
 
Determine if the vehicle was driven on a rough road, and the ABS could not detect this due to a malfunction. The PCM may interpret variations in crankshaft speed caused by the rough road as a misfire without an actual engine misfire present.
 
Refer to Diagnostic System Check for Antilock Brake System
 
Refer to Diagnostic System Check for the Engine Controls
 

Trouble Code: P1432



Fuel Pressure Sensor Circuit Low Input

Possible Causes:



Fuel tank pressure sensor is sticking or it is damaged
 
Fuel tank pressure sensor signal circuit is shorted to ground
 
Fuel tank pressure sensor is damaged or it has failed
 
PCM has failed
 

Trouble Code: P1433



Fuel Pressure Sensor Circuit Low Input

Possible Causes:



Fuel tank pressure sensor is sticking or it is damaged
 
Fuel tank pressure sensor signal circuit is shorted to ground
 
Fuel tank pressure sensor is damaged or it has failed
 
PCM has failed
 

Trouble Code: P1514



Throttle Body Performance

Possible Causes:



Inspect the throttle blade for damage and/or proper installation
 
Inspect the TAC module connectors for signs of water intrusion. When water intrusion occurs, multiple codes can set with no circuit or component faults apparent during diagnostic testing.
 
Physically and visually inspect the throttle body assembly, and throttle position sensor for damage and/or a loose mounting. Move the throttle blade from closed to wide open position without applying too much force. The throttle blade should move smoothly through the full range and should return to a slightly open position on its own.
 
If the TAC module detects a fault in the system, it may set more than one related code because of the many redundant tests that run continuously on this system. Locating and repairing one individual condition may fix more than one code.
 

Trouble Code: P1515



Control Module Throttle Actuator Position Performance

Possible Causes:



Throttle actuator motor CKT 1 is open, shorted to ground or B+
 
Throttle actuator motor CKT 2 is open, shorted to ground or B+
 
Throttle actuator motor is damaged or has failed
 
Throttle actuator motor control module has failed
 
TSB 00-06-04-035 contains a repair procedure for this code
 

Trouble Code: P1516



TAC Module Throttle Actuator Position Performance

Possible Causes:



TAC motor CKT 1 or CKT 2 is open, shorted to ground or B+
 
Throttle actuator motor CKT 1 is shorted to CKT 2
 
Throttle actuator motor control module has failed
 
TSB 03-04-06-034 contains a repair procedure for this code
 

Trouble Code: P1517



Throttle Actuator Control Module Performance

Possible Causes:



Test the charging system output (low voltage can set this code)
 
Inspect the TAC module connectors for signs of water intrusion. If water intrusion occurs, multiple codes may set without any circuit or component conditions found during diagnostic testing.
 
When the TAC module detects a fault condition, several TAC related codes set because there are redundant tests running.
 
TAC module has failed
 

Trouble Code: P1518



Throttle Actuator Control Module Serial Data Malfunction

Possible Causes:



DTC P1518 sets if the battery voltage is low. If the customer's concern is slow cranking or no crank due to low battery voltage, ignore the DTC P1518. Clear codes and retest.
 
DTC P1518 also sets when there is a short to B+ on the TAC module ground circuit. Inspect the fuses for the circuits that are in the TAC module harness (e.g., Brake & Cruise) for the fault.
 
DTC P1518 sets if the TAC module power circuit is shorted to a B+ supply circuit. The TAC module stays powered-up when the ignition switch is turned off. When the key on, the TAC module is powered-up before the PCM gets power. DTC 1518 is set because the TAC module did not detect signals from the PCM.
 
TAC module has failed
 

Trouble Code: P1631



Theft Deterrent - Start Enable Signal Not Correct

Possible Causes:



Refer to Diagnostic System Check for Theft Deterrent Module
 
Perform the Powertrain Onboard Diagnostic System Check
 
TSB 77-65-31 contains a repair procedure for this code
 

Trouble Code: P1635



5-Volt Reference 1 Circuit Malfunction

Possible Causes:



5v VREF circuit is shorted to sensor ground or chassis ground
 
5v VREF circuit, MAP or EGR sensor circuit is shorted to (B+)
 
5v VREF circuit shorted to EGR sensor High signal circuit
 
EGR solenoid valve (and sensor) is damaged or has failed
 
PCM has failed
 

Trouble Code: P1637



Generator 'L' Terminal Circuit Malfunction

Possible Causes:



A Scan Tool should display Inactive for the 'L' Terminal and 10-40% for the 'F' Terminal with the ignition "on". With the engine running, the display should indicate the 'L' Terminal is Active and the 'F' Terminal is higher than 5% on the tool display.
 
Generator 'L terminal circuit shorted to ground or to power (B+)
 
Generator 'F' terminal circuit is open or shorted to ground
 
Generator is damaged or has failed or the PCM has failed
 

 
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