Corvette 1997-2005

5.7L V8 VIN G Auto 5

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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, TP or MAP 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
 

Trouble Code: P1638



Generator 'F' Terminal Circuit Malfunction

Possible Causes:



Generator connector is damaged or has high resistance
 
Generator field duty cycle signal circuit is open or shorted
 
Generator is damaged or has failed
 
PCM has failed
 

Trouble Code: P1639



5-Volt Reference 2 Circuit Malfunction

Possible Causes:



A/C refrigerant pressure sensor VREF circuit is open or shorted to ground
 
A/C refrigerant pressure sensor VREF circuit is shorted to system power
 
A/C pressure sensor or FTP sensor is damaged or has failed
 
PCM has failed
 

Trouble Code: P1652



Powertrain Induced Chassis Pitch Output Circuit Malfunction

Possible Causes:



Chassis pitch output circuit is open, shorted to ground or to B+
 
Electronic Suspension Control Module has failed
 
PCM has failed
 

Trouble Code: P1689



Traction Control Delivered Torque Output Circuit Malfunction

Possible Causes:



Delivered torque circuit is open, shorted to ground or to B+
 
EBTCM is damaged or has failed
 
PCM has failed
 

Trouble Code: P1810



TFP Valve Position Switch Malfunction (4L60-E)

Possible Causes:



TFP valve position switch signal circuit is open or grounded
 
TFP valve position switch circuit shorted to another signal
 
TFP valve position switch is damaged or has failed
 
PCM has failed
 

Trouble Code: P1860



TCM PWM Solenoid Circuit Malfunction (4L80-E)

Possible Causes:



TCC solenoid control circuit is open, shorted to ground and to power (B+)
 
TCC solenoid power circuit is open (test the ENG IGN fuse)
 
TCC solenoid is damaged or has failed
 
PCM has failed
 

Trouble Code: P1870



Transaxle Component Slipping (4T60-E)

Possible Causes:



1-2 shift solenoid valve has sediment, damage or leaking seals
 
2-3 shift solenoid valve has sediment, damage or leaking seals
 
3-2 shift solenoid valve has sediment, damage or leaking seals
 
Valve body regulator apply valve stuck or regulator is scored
 
Torque converter front stator shaft bushing is worn, the stator roller clutch is not holding
 
Converter clutch valve is stuck or it is installed backwards
 
Converter clutch valve retaining ring is not positioned properly
 
Converter clutch outer valve spring is cocked
 
Pump to case gasket is not positioned properly
 
Orifice cup plugs are restricted or damaged
 
Over-tightened, or unevenly tightened pump body to cover bolts
 

Trouble Code: U1000



Class 2 Communication Malfunction

Possible Causes:



Class 2 circuit is open, shorted to ground or shorted to power
 
PCM ignition power circuit(s) has a high resistance condition
 
PCM main ground circuit(s) has a high resistance condition
 
SDM (module) could be shorted pulling the voltage low
 

Trouble Code: U1016



No Communication With Powertrain Control Module

Possible Causes:



PCM Class 2 circuit is open, shorted to ground or to B+
 
PCM ignition power circuit(s) has a high resistance condition
 
PCM main ground circuit(s) has a high resistance condition
 
PCM (module) may have failed and is pulling the circuit low
 

Trouble Code: U1048



No Communication With Rear Wheel Steering Control Module

Possible Causes:



RWSCM Class 2 circuit is open, shorted to ground or to B+
 
RWSCM ignition power circuit has a high resistance condition
 
RESCM main ground circuit(s) has a high resistance condition
 
RESCM (module) may have failed and is pulling the circuit low
 

Trouble Code: U1064



No Communication With Body Control Module

Possible Causes:



BCM Class 2 circuit is open, shorted to ground or to B+
 
BCM ignition power circuit has a high resistance condition
 
BCM main ground circuit(s) has a high resistance condition
 
BCM (module) may have failed and is pulling the circuit low
 

Trouble Code: U1088



No Communication With SDM (Restraint Module)

Possible Causes:



SDM Class 2 circuit is open, shorted to ground or to B+
 
SDM ignition power circuit has a high resistance condition
 
SDM main ground circuit(s) has a high resistance condition
 
SDM (module) may have failed and is pulling the circuit low
 

Trouble Code: U1096



No Communication With Instrument Panel Cluster

Possible Causes:



IPC Class 2 circuit is open, shorted to ground or to B+
 
IPC ignition power circuit has a high resistance condition
 
IPC main ground circuit(s) has a high resistance condition
 
IPC (module) may have failed and is pulling the circuit low
 

Trouble Code: U1097



No Communication With Driver Information Center

Possible Causes:



DIC Class 2 circuit is open, shorted to ground or to B+
 
DIC ignition power circuit has a high resistance condition
 
DIC main ground circuit(s) has a high resistance condition
 
DIC (module) may have failed and is pulling the circuit low
 

Trouble Code: U1151



No Communication With Vehicle Interface Unit

Possible Causes:



VIU Class 2 circuit is open, shorted to ground or to B+
 
VIU ignition power circuit has a high resistance condition
 
VIU main ground circuit(s) has a high resistance condition
 
VIU (module) may have failed and is pulling the circuit low
 

Trouble Code: U1152



No Communication With HVAC Control Module

Possible Causes:



HVAC Class 2 circuit is open, shorted to ground or to B+
 
HVAC ignition power circuit has a high resistance condition
 
HVAC main ground circuit(s) has a high resistance condition
 
HVAC (module) may have failed and is pulling the circuit low
 

Trouble Code: U1255



Class 2 Communications Malfunction

Possible Causes:



Class 2 circuit is open, shorted to ground or shorted to power
 
PCM ignition power circuit(s) has a high resistance condition
 
PCM main ground circuit(s) has a high resistance condition
 

Trouble Code: U1305



Class 2 Data Link High or Low

Possible Causes:



Class 2 serial data line has either a high or low voltage condition on the circuit, and the module cannot identify the fault
 
One or more modules on Class 2 line has an short to power
 
One or more modules on the Class 2 line has a short to ground
 

 
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