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

6.6L V8 VIN 1 Auto 3

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Trouble Code: P0611



Fuel Injection Control Module Performance

Possible Causes:



FICM is damaged
 

Trouble Code: P0612



Ignition Relay Control Circuit Malfunction

Possible Causes:



Ignition relay circuit is shorted to system power
 
Ignition relay is damaged or it has failed
 
ECM has failed
 

Trouble Code: P0641



5-Volt Reference 1 Circuit Malfunction

Possible Causes:



5v VREF circuit to APP1 or APP3 is shorted to ground or shorted to system power
 
FRP or EOP sensor is shorted to ground or shorted to system power
 
PCM has failed
 

Trouble Code: P0650



Malfunction Indicator Lamp Circuit Malfunction

Possible Causes:



MIL control circuit is open or shorted to ground
 
MIL control circuit is shorted to system power
 
MIL control power circuit is open in the Instrument Cluster
 
MIL (the lamp) is damaged or has failed
 
Instrument Cluster or the PCM has failed
 

Trouble Code: P0651



5-Volt Reference 2 Circuit Malfunction

Possible Causes:



5v VREF circuit to APP2 or APP2, FRP or EOP sensor is shorted to ground or shorted to VREF
 
ECM has failed
 

Trouble Code: P0700



Malfunction Indicator Lamp Circuit Malfunction (TCM)

Possible Causes:



MIL control circuit is shorted to ground
 
Check the TCM for any trouble codes in memory that are responsible for the request to turn on the MIL
 
TCM has failed
 

Trouble Code: P0711



TFT Sensor Range/Performance (4L60-E, 4L80-E)

Possible Causes:



ATF fluid level too low or the fluid is contaminated or burnt
 
TFT sensor is contaminated, damaged or "skewed"
 
PCM has failed
 

Trouble Code: P0712



TFT Sensor Circuit Low Input (4L60-E, 4L80-E)

Possible Causes:



TFT sensor signal circuit is shorted to sensor or chassis ground
 
TFT sensor is damaged or has failed (it may be shorted)
 
PCM has failed
 

Trouble Code: P0713



TFT Sensor Circuit High Input (4L60-E. 4L80-E)

Possible Causes:



TFT sensor signal circuit is open between the sensor and PCM
 
TFT sensor signal circuit is shorted to VREF or system power
 
TFT sensor is damaged or has failed (it may be open)
 
PCM has failed
 

Trouble Code: P0716



A/T Input Shaft Speed Sensor Circuit Malfunction (4L80-E)

Possible Causes:



ISS positive (+) circuit is open, shorted to ground or to power
 
ISS negative (-) circuit is open, shorted to ground or to power
 
ISS terminals are corroded or damaged (check for moisture)
 
ISS signal wires routed too close to the Ignition system cables
 
PCM has failed
 

Trouble Code: P0717



A/T Input Shaft Speed Sensor Low Input (4L80-E)

Possible Causes:



ISS positive (+) circuit is open, shorted to ground or to power
 
ISS negative (-) circuit is open, shorted to ground or to power
 
ISS is damaged or has failed
 
PCM has failed
 
TSB 00-07-30-015 contains a repair procedure for this code
 

Trouble Code: P0719



TCC Brake Switch Circuit Low Input (4L60-E, 4L80-E)

Possible Causes:



TCC brake switch circuit is open or shorted to ground
 
TCC brake switch power circuit is open (check the CRUISE, FAN ALT or other related fuse in underhood junction block)
 
TCC brake switch is out of adjustment or damaged
 
PCM has failed
 

Trouble Code: P0722



Output Shaft Speed Sensor Circuit Low Input (4L80-E)

Possible Causes:



OSS positive (+) circuit is open or shorted to ground
 
OSS negative (-) circuit is open or shorted to ground
 
OSS terminals are corroded or damaged (check for moisture)
 
PCM has failed
 

Trouble Code: P0723



Output Shaft Speed Sensor Circuit High Input (4L80-E)

Possible Causes:



OSS positive (+) circuit is open or shorted to system power
 
OSS negative (-) circuit is open or shorted to system power
 
OSS terminals are corroded or damaged (check for moisture)
 
PCM has failed
 

Trouble Code: P0724



TCC Brake Switch High Input (4L60-E, 4L80-E)

Possible Causes:



Check for ABS trouble codes (they can cause this code to set)
 
TCC brake switch circuit is shorted to system power
 
TCC brake switch is out of adjustment or damaged
 
PCM has failed
 

Trouble Code: P0730



Incorrect Gear Ratio (4L80-E)

Possible Causes:



ATF level is too low, or the fluid is burnt or contaminated
 
ISS or OSS signal circuit has an intermittent fault condition
 
Inspect for debris in the transmission pan or internal damaged
 
Possible vehicle overloading, exceeding the trailer towing limit, or towing in overdrive events occurred (discuss with customer)
 

Trouble Code: P0741



TCC System Stuck Off - Mechanical (4L80-E)

Possible Causes:



ATF level is too low, or the fluid is burnt or contaminated
 
Inspect transmission lines to radiator for bends or restrictions
 
Oil pressure screen is clogged or debris in the oil pan
 
TCC control valve is stuck "off" due to sediment or binding
 
TCC regulator valve is stuck "off" due to sediment or binding
 
TCC feed valve is stuck "off" due to sediment or binding
 
TCC solenoid valve O-ring or turbine shaft seals leaking or cut
 

Trouble Code: P0742



TCC System Stuck Off - Mechanical (4L60-E)

Possible Causes:



Exhaust orifice in the TCC solenoid valve is clogged
 
Converter clutch apply valve stuck in the "on" (apply) position
 
Valve body gasket is damaged or misaligned
 
Release pass is clogged or restricted
 
Transmission cooler line is bent or restricted
 

Trouble Code: P0751



A/T 1-2 Shift Solenoid - No 1st Or 4th Gear (4L60-E, 4L65-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: 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 (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
 

Trouble Code: P0756



2-3 Shift Solenoid - No 2nd or 3rd Gear (4L80-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
 

Trouble Code: P0758



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

Possible Causes:



2-3 shift solenoid control circuit is open, shorted to ground or 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
 

Trouble Code: P0802



Malfunction Indicator Lamp Circuit Malfunction

Possible Causes:



TCM MIL Request circuit is open, shorted to ground or to B+
 
ECM has failed
 
TCM has failed
 

Trouble Code: P0850



Title: A/T TCC PWM Solenoid Malfunction (4L60-E, 4L65-E)

Possible Causes:



ATF is burnt or contaminated
 
Transmission has an internal malfunction, or the TCC PWM solenoid seal is damaged
 
TCC PWM solenoid has failed, or the Transmission has failed
 

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: P1093



Fuel Rail Pressure Range/Performance

Possible Causes:



CNG fuel injector 8 connector is damaged, open or shorted
 
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: P1094



Fuel Rail Pressure Solenoid Circuit Malfunction

Possible Causes:



Check the engine oil for fuel contamination
 
Fuel pressure regulator solenoid circuit is shorted to ground
 
If you have to prime the fuel system, inspect for a restricted fuel supply line or a fuel supply line air leak
 
ECM has failed
 

Trouble Code: P1125



Accelerator Pedal Position Sensor Circuit Malfunction

Possible Causes:



If DTC P0641 is set, repair the cause of this trouble code first.
 
If DTC P0641 is not set, refer to the other APP sensor codes that are set to repair the cause of this trouble code.
 

Trouble Code: P1172



Secondary Fuel Pump Insufficient/No Fuel Flow

Possible Causes:



Fuel transfer relay control circuit is open or shorted to ground
 
Fuel pump relay ground circuit is open
 
Fuel pump relay power circuit is open (check the ECB B fuse)
 
Fuel pump relay or the Fuel transfer pump is damaged or has failed
 
ECM 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
 

 
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