CODE U1000 and CODE P1626

DTC P1626 Theft Deterrent Fuel Enable Signal Not Received

Circuit Description
The control module communicates with other modules using the Class 2 Serial Data circuit. The vehicle theft deterrent (VTD) (Passlock) module sends a vehicle security password to the control module, via the Class 2 Serial Data circuit, after the system has sensed the proper operation of the ignition switch and lock, and determined that the switch and lock have not been tampered with. If this password matches the password stored in the control module, fuel will be enabled. If the VTD (Passlock) module does not send a password, or if the control module does not receive it, the vehicle will not start, or it may start and stall. This will set a DTC P1626 in the control module memory. If communication is lost after receiving the password, the VTD (Passlock) system will go into Fail Enable, set a U1192 in the control module, and the engine will continue to run. This will allow the engine to restart on future ignition cycles but may set a DTC P1626 as the engine is started. If the battery is disconnected or the codes are cleared, the vehicle will lose its Fail Enable status and will not start until communication is re-established.


Diagnostic Aids
Important: Do not clear DTCs unless directed by a diagnostic procedure. Clearing DTCs will also clear valuable Freeze Frame and Failure Records data.
• Check for published service bulletins relating to exhibited symptoms or component operation.
• Inspect all related wiring and connections including the VCM and VTD (Passlock) Control Module connections. These may cause an intermittent malfunction.
• If the Class 2 serial data circuit is shorted to ground or shorted to voltage, then all systems connected to the serial data circuit will not be able to communicate properly. Systems capable of storing loss of communications DTCs (DTCs with the letter U as a prefix) will have these codes stored in their memory. If a DTC U1192 is stored in the VCM memory along with the P1626, then a fault occurred at some point after the VCM received the correct password. The VTD must also be checked for intermittent operation due to a loss of power or ground to the module itself. After repairing the cause of DTC 1626, clear all DTCs from the systems capable of storing this DTC and DTC U1192.
• The VTD (Passlock) parameters can be monitored in the VCM data display with a scan tool.
• The scan tool's Diagnostic Circuit Check can be used to:
- Monitor the Class 2 Serial Data circuit for modules which have been or are communicating.
- Monitor for loss of communications DTCs (DTCs with the letter U as a prefix: U1001-U1199).
- Clear loss of communication DTCs. When a Clear Codes command is issued, all codes, Freeze Frame and Failure Records information is cleared.
• The scan tool's Class 2 Message Monitor will show the status of each module on the Class 2 circuit. A status of Active indicates that the module is communicating with the scan tool. An Inactive status indicates that the module previously communicated with the scan tool, but is not communicating currently. The inactive status will only appear if the loss of communication occurs while on the Message Monitor screen. If a module is not listed at all, then the missing module never successfully established communications with the scan tool or lost communication while on another screen. Refer to Data Link Communications System Check in Wiring Systems for the complete Class 2 data link to determine if there are any unlisted modules.
An intermittent may be caused by any of the following conditions:
• A poor connection
• Rubbed through wire insulation
• A broken wire inside the insulation
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.

How do you know it's a passkey 3 anti-theft system problem ? Light lit on the insturment cluster ? Padlock car symbol . If the security light is lit ,do you have a scan tool that can read these codes
DTC B2960
DTC B3031
DTC B3055
DTC P1626
DTC P1629
DTC P1630
DTC P1631

Not a code reader for the Engine OBD 2 codes .

Hard to say why the light comes on , may have a diagnostic trouble code stored in the BCM - body control module ! Do you have a bunch of other key's on the same ring as the vehicle key ?
Passlock™ System
The theft deterrent system has been incorporated into the body control module (BCM). The theft deterrent system prevents the vehicle operation if the correct key is not used in order to start the vehicle. The ignition key turns the ignition lock cylinder. The cylinder rotation produces an analog voltage code in the Passlock™ sensor. This voltage code is received by the BCM. The BCM compares the voltage code to the previously learned voltage code. If the codes match, a class 2 message is sent from the BCM to the powertrain control module (PCM). The message enables the fuel injectors and the crank relay.
The design of the Passlock™ system is to prevent vehicle theft by disabling the engine unless the ignition lock cylinder rotates properly by engaging the correct ignition key. The system is similar in concept to the passkey system. However, the Passlock™ system eliminates the need for a key mounted resistor pellet. The components of the Passlock™ system are as follows:
• The ignition lock cylinder
• The ignition switch
• The Passlock™ sensor
• The body control module (BCM)
• The SECURITY indicator
• The powertrain control module (PCM)
When anyone of these codes set the BCM will turn on the SECURITY light !
DTC B2947
DTC B2948
DTC B2957
DTC B2958
DTC B2960
DTC B3031
DTC B3033
DTC P1626
DTC P1629
DTC P1630
DTC P1631

Your best bet , take it to a qualified repair shop an have it checked !Here are some reasons for the light to come on .
Conditions for Setting the DTC
The BCM detects a short to ground on the Passlock sensor power circuit for 1 second, with the ignition switch in the ACCESSORY, ON, or START position.
The PCM has detected a loss of the state of health serial data message from the theft deterrent system.

have you put obd11 scanner on it to find error code.
DTC P1626 Theft Deterrent Fuel Enable Signal Lost
Circuit Description
The Vehicle Theft Deterrent (VTD) system is incorporated within the body control module (BCM). The powertrain control module(PCM) monitors the state of health serial data message from the Theft Deterrent system to ensure that the PCM to BCM communications is established. If the PCM detects a loss of the state of health message while the engine is running, DTC P1626 will set. DTC P1626 can cause a no-start condition or normal operation depending on when the loss of Theft Deterrent system communication was detected. The engine will continue to start and run if the condition that set DTC P1626 occurred after the PCM received a valid theft deterrent password from the BCM and already allowed fuel during the ignition cycle. The engine will start and immediately stall if the condition that set DTC P1626 occurred before the PCM received a valid theft deterrent password. With this condition present, the PCM will inhibit fuel delivery and disable the starter until a valid theft deterrent password is detected. Refer to Content Theft Deterrent (CTD) Circuit Description .

Conditions for Running the DTC
The Theft Deterrent system has allowed fuel delivery.
Conditions for Setting the DTC
The PCM has detected a loss of the state of health serial data message from the Theft Deterrent system.

Action Taken When the DTC Sets
The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.

Conditions for Clearing the MIL/DTC
The DTC becomes history when the conditions for setting the DTC are no longer present.
The history DTC clears after 40 malfunction free warm-up cycles.
The PCM receives a clear code command from the scan tool.
Diagnostic Aids,
An intermittent may be caused by:

• A poor connection

• Rubbed through wire insulation

• A wire broken inside the insulation

Check for the following conditions:, • Intermittent short circuit on the serial data circuit -- Refer to Data Link Communications Operation in Data Link Communications. Be sure to check all related wiring for an intermittent short to ground or short to voltage.

• Poor connection -- Inspect the wiring harness for damage. Check for an intermittent short or open circuit in the wiring harness related to the BCM, including the ignition, battery feed, ground, and Serial Data circuits.

DTC U1000 and U1255
Class 2 Communication Malfunction , Do you know what class 2 serial data communication network is ? What module set this code an what kind of scan tool did you use to read this code .
Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the ID number of the module which sent the message for State of Health monitoring, Node Alive messages. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. When a module does not associate an ID number with at least one critical parameter within about 5.5 seconds of beginning serial data communication, DTC U1000 or U1255 is set. When more than one critical parameter does not have an ID number associated with it, the DTC will only be reported once.
The table below list the modules on the Class 2 Serial Data Circuit that will set a U1000 or U1255 and should be actively communicating the previously described messages on the Class 2 Serial Data Circuit.

Control Module

ID Number
Body Control Module (BCM)
064
Electronic Brake Control Module (EBCM)
040
Instrument Panel Cluster (IPC)
096
Radio
128
Powertrain Control Module (PCM)
016
Sensing and Diagnostic Module (SDM)
088
Diagnostic Aids
When a malfunction such as a open fuse to a module occurs while modules are communicating, a Loss of Communication DTC is set as current. When the modules stop communicating, ignition is turned off, the current Loss Communication DTC is cleared but the history DTC remains. When the modules begin to communicate again, the ignition is turned on, the module with the open fuse will not be learned by the other modules so U1000 or U1255 is set current by the other modules. If the malfunction occurs when the modules are not communicating, only U1000 or U1255 is set.
Test Description
The numbers below refer to the step numbers on the diagnostic table.

1. A DTC U1001 - U1254 Lost Communications with with a history status may indicate the cause of U1000 or U1255.


2. The modules not communicating are the likely cause of U1000 or U1255. The modules that are available on the class 2 serial data circuit are listed in the Circuit Description.


3. The module which was not communicating due to a poor connection to the class 2 serial data circuit may have set DTC U1001 - U1254 Lost Communications with for those modules that it was monitoring.


4. The modules which can communicate indicate the module which cannot communicate. You must clear the serial data communication DTCs from these modules to avoid future misdiagnosis.


5. If all modules are communicating, the module which set U1000 or U1255 may have done so due to some other condition.


6. The module which set U1000 or U1255 is the likely cause of the malfunction.

1

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. Record the DTCs set in each module. If using a Tech 2, use the Class 2 DTC Check feature to determine which modules have DTCs set.

Did you record any DTCs in the range of U1001-U1254 with a history status?
Go to Diagnostic Trouble Code (DTC) List
Go to Step 2

2

1. Turn ON the ignition, with the engine OFF.
2. Attempt to communicate with each module on the class 2 serial data circuit. If using a Tech 2, obtain this information using the class 2 Message Monitor feature.
3. Record all of the modules communicating on the class 2 serial data circuit.
4. Compare the list of modules which are communicating to the list given in Circuit Description.

Does any module on the class 2 serial data circuit not communicate?
YES - Go to Step 3
NO - Go to Step 12
Test the following circuits of the module that is not communicating for an open or short to ground:
?€¢
The battery positive voltage supply circuits

?€¢
The switched battery positive supply circuits

?€¢
The battery positive voltage output circuits

?€¢
The ignition voltage input circuits

?€¢
The ignition voltage output circuits

Refer to the following:
?€¢
Control Module References in Body Control System for the applicable schematic

?€¢
Circuit Testing in Wiring Systems

?€¢
Wiring Repairs in Wiring Systems

Did you find and correct the condition?

5

Important: Inspect all connectors in the serial data communications circuit.
Refer to the following:
?€¢
Data Link Connector Schematics

?€¢
Testing for Intermittent Conditions and Poor Connections in Wiring Systems

?€¢
Connector Repairs in Wiring Systems

1. Turn OFF the ignition.
2. Test the class 2 serial data circuits of the module that is not communicating for an open. Refer to the following:

?€¢
Data Link Connector Schematics

?€¢
Circuit Testing in Wiring Systems

?€¢
Wiring Repairs in Wiring Systems

Did you find and correct the condition?
Go to Step 8
Go to Step 6

6
Inspect the harness connector of the module that is not communicating for poor connections and terminal tension at the following circuits:
?€¢
The battery positive voltage input circuits

?€¢
The switched battery positive voltage supply

?€¢
The battery positive voltage output circuits

?€¢
The ignition voltage input circuits

?€¢
The ignition voltage output circuits

?€¢
The ground circuits

?€¢
The class 2 serial data circuits

Refer to the following:
?€¢
Control Module References in Body Control System for the applicable schematic

?€¢
Testing for Intermittent Conditions and Poor Connections in Wiring Systems

?€¢
Connector Repairs in Wiring Systems

Did you find and correct the condition?
Go to Step 8
Go to Step 7

7

Important: Perform the module programming or setup procedure if required.
Replace the module that is not communicating. Refer to Control Module References in Body Control System for the appropriate Repair Instructions for the module replacement.
Did you complete the replacement?
Go to Step 10
--

8

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. Select the Display DTCs function for the module which was not communicating.

Does the scan tool display any DTCs which do not begin with a "U"?
Go to Control Module References in Body Control System for applicable Diagnostic System Check
Go to Step 9

9
Use the scan tool in order to clear the DTCs.
Did you complete the action?
Go to Step 10
--

10

Select the Display DTCs function for the modules which had U1000 or U1255 set as a current DTC.
Does the scan tool display DTCs which do not begin with a "U"?
Go to Control Module References in Body Control System for applicable Diagnostic System Check
Go to Step 11

11

Use the scan tool in order to clear the DTCs.
Did you complete the action?
System OK
--

12
Did you record any other DTCs for the modules which had U1000 or U1255 set as a current DTC?
Go to Control Module References in Body Control System for applicable Diagnostic System Check
Go to Step 13

13

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. Use the scan tool in order to clear the DTCs.
4. Turn OFF the ignition for at least 5 seconds.
5. Turn ON the ignition with the engine OFF.
6. Select the Display DTCs function.

Does the scan tool display U1000 or U1255 set as a current DTC?
Go to Step 14
Go to Diagnostic Aids

14
Important: Perform the module programming or setup procedure if required.
Replace the module which had U1000 or U1255 set as a current DTC. Refer to Control Module References in Body Control System for the appropriate Repair Instructions for the module replacement.
Did you complete the replacement?
System OK

DTC P1626 Theft Deterrent Fuel Enable Signal Not Received
The control module communicates with other modules using the Class 2 Serial Data circuit. The vehicle theft deterrent (VTD) (Passlock) module sends a vehicle security password to the control module, via the Class 2 Serial Data circuit, after the system has sensed the proper operation of the ignition switch and lock, and determined that the switch and lock have not been tampered with. If this password matches the password stored in the control module, fuel will be enabled. If the VTD (Passlock) module does not send a password, or if the control module does not receive it, the vehicle will not start, or it may start and stall. This will set a DTC P1626 in the control module memory. If communication is lost after receiving the password, the VTD (Passlock) system will go into Fail Enable, set a U1192 in the control module, and the engine will continue to run. This will allow the engine to restart on future ignition cycles but may set a DTC P1626 as the engine is started. If the battery is disconnected or the codes are cleared, the vehicle will lose its Fail Enable status and will not start until communication is re-established
Go on YouTube an search passlock by pass , or you can take it to the dealer .

help me

Code U1000 is saying the ECM lost communication with the BCM which can happen when the key switch is turned far enough to stop the engine but not enough to turn the accessories off.
Code 463 is for fuel level sensor circuit high which is a problem with the fuel gauge or the sending unit in the tank.
Code 1626 involves the theft deterrent system.
P1626 CHEVROLET - Theft Deterrent Fuel Enable Signal Not Received
Read more: http://engine-codes.com/p1626_chevrolet.html#ixzz210PRFRO9

The code 1626 could be the issue - the passkey system may not be reading the chip in your key.

Do you know what U code's are for ? How did you pull this code ? There is no U0155 , U code's start at
Diagnostic Trouble Code (DTC) List
DTC
Diagnostic Procedure
Modules
U1000
DTC U1000 and U1255
Audio Amplifier, Cellular Telephone Module, DDM, DDSA, Digital Radio Receiver, DIM, EBCM, ESC, FPDM, HVAC Control Module - Auxiliary, IPC, IPM, LMDM, LRDM, MSM, PCM, Radio, Remote Playback Device CD Changer, RCDLR, RIM, RMDM, RRDM, SDM, Steering Column Module, Theft Deterrent Control Module, VCIM, Window Switch - Front Passenger w/armored car
U1016
DTC U1001-U1254
Audio Amplifier, Cellular Telephone Module, DDM, DDSA, Digital Radio Receiver, DIM, EBCM, ESC, FPDM, HVAC Control Module - Auxiliary, IPC , IPM, LMDM, LRDM, MSM, Radio, RCDLR, RIM, RRDM, RMDM, SDM, Steering Column Module, Theft Deterrent Control Module, VCIM, Window Switch - Front Passenger w/armored car
U1040
DTC U1001-U1254
IPC, PCM, SDM
U1056
DTC U1001-U1254
EBCM, PCM
U1064
DTC U1001-U1254
Audio Amplifier, Cellular Telephone Module, DDM, DDSA, Digital Radio Receiver, DIM, EBCM, ESC, FPDM, HVAC Control Module - Auxiliary, IPC, IPM, LMDM, LRDM, MSM, PCM, Radio, RCDLR, Remote Playback Device CD Changer, RIM, RMDM, RRDM, SDM, Steering Column Module, Theft Deterrent Control Module, VCIM, Window Switch - Front Passenger w/armored car
U1065
DTC U1001-U1254
DDM, DIM, ESC, FPDM, IPC, LMDM, LRDM, VCIM, HVAC Control Module - Auxiliary, PCM, Radio, RIM, RMDM, RRDM, VCIM
U1066
DTC U1001-U1254
DDM, FPDM, IPC, IPM, PCM
U1088
DTC U1001-U1254
IPC
U1096
DTC U1001-U1254
PCM, SDM
U1128
DTC U1001-U1254
Audio Amplifier, Cellular Telephone Module, Digital Radio Receiver, Remote Playback Device CD Changer, VCIM
U1129
DTC U1001-U1254
Radio
U1130
DTC U1001-U1254
Radio
U1137
DTC U1001-U1254
Radio
U1144
DTC U1001-U1254
IPC, Radio
U1151
DTC U1001-U1254
Radio
U1160
DTC U1001-U1254
IPC, RIM
U1161
DTC U1001-U1254
IPC, RIM
U1162
DTC U1001-U1254
IPC, RIM
U1163
DTC U1001-U1254
IPC, RIM
U1164
DTC U1001-U1254
DDM, Digital Radio Receiver, DIM, FPDM, IPC, LRDM, MSM, VCIM, Radio, RIM, RRDM, Steering Column Module
U1165
DTC U1001-U1254
DDM, FPDM, LRDM, RRDM
U1176
DTC U1001-U1254
IPC
U1192
DTC U1001-U1254
IPC, PCM
U1255
DTC U1000 and U1255
Audio Amplifier, Cellular Telephone Module, DDM, DDSA, Digital Radio Receiver, DIM, EBCM, ESC, FPDM, HVAC Control Module - Auxiliary, IPC, IPM, LMDM, LRDM, MSM, PCM, Radio, Remote Playback Device CD Changer, RCDLR, RIM, RMDM, RRDM, SDM, Steering Column Module, Theft Deterrent Control Module, VCIM, Window Switch - Front Passenger w/armored car
U1300
DTC U1300, U1301, or U1305
Audio Amplifier, Cellular Telephone Module, DDM, DDSA, Digital Radio Receiver, DIM, EBCM, ESC, FPDM, HVAC Control Module - Auxiliary, IPC, IPM, LMDM, LRDM, MSM, PCM, Radio, Remote Playback Device CD Changer, RCDLR, RIM, RMDM, RRDM, SDM, Steering Column Module, Theft Deterrent Control Module, VCIM, Window Switch - Front Passenger w/armored car
U1301
DTC U1300, U1301, or U1305
Audio Amplifier, Cellular Telephone Module, DDM, DDSA, Digital Radio Receiver, DIM, EBCM, ESC, FPDM, HVAC Control Module - Auxiliary, IPC, IPM, LMDM, LRDM, MSM, PCM, Radio, Remote Playback Device CD Changer, RCDLR, RIM, RMDM, RRDM, SDM, Steering Column Module, Theft Deterrent Control Module, VCIM, Window Switch - Front Passenger w/armored car
U1305
DTC U1300, U1301, or U1305
Audio Amplifier, Cellular Telephone Module, DDM, DDSA, Digital Radio Receiver, DIM, EBCM, ESC, FPDM, HVAC Control Module - Auxiliary, IPC, IPM, LMDM, LRDM, MSM, PCM, Radio, Remote Playback Device CD Changer, RCDLR, RIM, RMDM, RRDM, SDM, Steering Column Module, Theft Deterrent Control Module, VCIM, Window Switch - Front Passenger w/armored car

The data link connector (DLC) allows a scan tool to communicate with the class 2 serial data line. The serial data line is the means by which the microprocessor-controlled modules in the vehicle communicate with each other. Once the scan tool is connected to the class 2 serial data line through the DLC, the scan tool can be used to monitor each module for diagnostic purposes and to check for diagnostic trouble codes (DTCs). Class 2 serial data is transmitted on a single wire at an average of 10.4 kbps. This value is an average; class 2 uses a variable pulse width modulation to carry data and depending on the message it may operate faster or slower. The bus will float at a nominal 7 volts during normal operation. Each module can pull this lower during the transmission. The bus is not at battery positive voltage or ground potential during normal operation. When the ignition switch is in RUN, each module communicating on the class 2 serial data line sends a state of health (SOH) message every 2 seconds to ensure that the module is operating properly. When a module stops communicating on the class 2 serial data line, for example, if the module loses power or ground, the SOH message it normally sends on the data line every 2 seconds disappears. Other modules on the class 2 serial data line, which expect to receive that SOH message, detect its absence; those modules in turn set an internal DTC associated with the loss of SOH of the non-communicating module. The DTC is unique to the module which is not communicating; for example, when the inflatable restraint sensing and diagnostic module (SDM) SOH message disappears, several modules set DTC U1088. Note that a loss of serial data DTC does not normally represent a failure of the module that set it.

Your best bet ,take it to a qualified repair shop.