CTS 2003-2005

3.8L V6 VIN 1 Auto 4

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Trouble Code: P1631



Theft Deterrent Enable Signal Not Correct

Possible Causes:



This code indicates that the VTD password that the PCM has learned does not agree with the password being received from the theft deterrent system. This condition can occur if an incorrect key is being used when attempting to start the vehicle or if the Theft Deterrent Module has been replaced and the PCM password learn function has not been enabled.
 
Refer to Programming the Theft Deterrent System
 
Perform the Powertrain Onboard Diagnostic System Check
 

Trouble Code: P1635



5-Volt Reference 'A' Circuit Malfunction

Possible Causes:



5v VREF circuit is shorted to sensor ground or chassis ground
 
5v VREF circuit, MAP or FTP 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: P1639



5-Volt Reference 'B' Circuit Malfunction

Possible Causes:



A/C refrigerant pressure sensor VREF circuit is open, shorted to ground or shorted to system power
 
A/C refrigerant pressure sensor is damaged or PCM has failed
 
TSB 61-65-61 contains a repair procedure for this code
 

Trouble Code: P1640



Output Driver 1 Input Voltage High Input

Possible Causes:



EVAP Vent control circuit open, shorted to ground or to B+
 
Fan relay 1 control circuit is open, shorted to ground or to B+
 
Fan relay 2 or 3 control circuit is open, shorted to ground or B+
 
PCM has failed
 

Trouble Code: P1670



Output Driver 4 Input Voltage High Input

Possible Causes:



A/C relay control, Fan 1 or Fan 2 control circuit is open, shorted to ground or to power
 
MIL (lamp) control circuit is open, shorted to ground or to B+
 
A/C Relay, Fan 1, Fan 2 and MIL power circuit(s) are open
 
Check for a possible battery over-charge condition
 
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 as failed, or the PCM has failed
 
TSB 00-06-04-023 contains a repair procedure for this code
 

Trouble Code: P1810



Transmission Pressure Switch Manifold Circuit Malfunction

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: P1811



Maximum Adaptive & Long Term Shift (4T65-E)

Possible Causes:



Ask customer about overloading vehicle, exceeding trailer-towing limit, or towing in O/D
 
ATF level is low, or the fluid is contaminated or burnt
 
1-2 accumulator piston seals rolled or damaged
 
1-2 accumulator piston and pin missing, binding or damaged
 
Forward servo assembly damaged or misassembled
 
Oil pump assembly damaged or missing components
 
Spacer plate and gaskets damaged or misassembled
 
Driven sprocket support seals damaged or missing
 
2nd clutch piston and seal assembly binding or damaged
 
2nd clutch fiber and steel plates misassembled or damaged
 
Second clutch spring assembly damaged or misassembled
 
Forward band burned, damaged or misassembled
 
1-2 support roller clutch assembly damaged or misassembled
 

Trouble Code: P1812



Torque Converter Overstressed (4T65-E)

Possible Causes:



ATF level is low or the fluid is burnt or contaminated
 
ATF filter is clogged or not properly installed/seated
 
Vehicle used for towing or driven while overloaded
 

Trouble Code: P1819



Internal Mode Switch - No Start (4T65-E)

Possible Causes:



Inspect the transmission linkage from the range selector to the manual shift shaft for proper adjustment
 
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: P1822



Internal Mode Switch 'B' Circuit Low Input (4T65-E)

Possible Causes:



IMS Signal 'B' circuit is open or has a high resistance condition
 
Transmission has internal problems / may need an overhaul
 

Trouble Code: P1823



Internal Mode Switch 'P' Circuit Low Input (4T65-E)

Possible Causes:



IMS Signal 'P' circuit is shorted to sensor or chassis ground
 
Transmission has internal problems / may need an overhaul
 

Trouble Code: P1825



Internal Mode Switch - Invalid Range (4T65-E)

Possible Causes:



IMS Signal 'A', 'B', 'C' and 'P' possible short to ground condition
 
IMS Signal 'A', 'B', 'C' and 'P' possible open or high resistance
 
Transmission has internal problems / may need an overhaul
 
PCM has failed
 

Trouble Code: P1826



Internal Mode Switch - Invalid Range (4T65-E)

Possible Causes:



IMS Signal 'C' circuit is open or has a high resistance condition
 
Transmission has internal problems / may need an overhaul
 

Trouble Code: P1860



TCC PWM Solenoid Circuit Malfunction (4T60-E)

Possible Causes:



TCC solenoid control circuit is open or shorted to ground
 
TCC solenoid control circuit is shorted to system power (B+)
 
TCC solenoid power circuit is open (test ENG or TRANS fuse)
 
TCC solenoid is damaged or has failed
 
PCM has failed
 

Trouble Code: P1870



Transaxle Component Slipping (4T60-E)

Possible Causes:



Check the ATF level and condition (look for burnt fluid)
 
Transmission may have internal damage (a mechanical fault)
 

Trouble Code: P1887



TCC Release Switch Circuit Malfunction (4T65-E)

Possible Causes:



TCC release switch signal circuit is open
 
Turbine shaft O-ring seal leaks, oil seal rings missing/damaged.
 
TCC control valve damaged or No. 1 check ball is damaged
 
Spacer plate release exhaust blocked or case cover or spacer plate gaskets damaged
 
TSB 02-07-30-022A contains a repair procedure for this code
 

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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