did you try to remove the code # with a diagnostic code retrieveing tool, this will remove the light from being on in the system, providing the computer is functioning properly, if you do not have the tool to do this with, then disconnect your positive battery cable, for about 1 minute, then reconnect it back up, and see if light is out. you will have to reset your vehicles clock, and possibly some radio functions.
There is a bad Power Control Module (PCM) ! You should have around 5 Volts when backprobed both Camshaft Position (CMP) and Crankshaft Position (CKP) sensors.
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Security light lit in the instrument cluster ? Do you know how this starting system works ?
Circuit Description
For ignition switch power modes refer to Body Control System Description and Operation . Once the ignition is placed in the Run/Crank position, the control circuit of the Run/Crank relay is grounded by the body control module (BCM). With the Run/Crank relay switch closed, battery positive voltage flows through it and on to the park/neutral position (PNP) switch. With the PNP switch in either the Park or Neutral position, battery positive voltage will flow to the START relay coil supply voltage input terminal of the engine control module (ECM) and the coil side of the START relay. Placing the ignition in the START position sends a message to the ECM requesting engine start. If the ECM has determined that the transmission is in Park or Neutral and theft is not active, it will supply 12 volts to the control circuit of the START relay. Battery positive voltage will then flow through the switch side of the START relay to the S terminal of the starter solenoid, cranking the engine.
Rather then guessing, hooking up a scan tool an checking codes and viewing live data to see if all inputs and outs from the BCM an PCM are what they should be.
DTC P0615
DTC P0615 Starter Relay Control Circuit
The engine control module (ECM) supplies 12 volts to the control circuit of the START relay when start enable has been requested. The ECM monitors this circuit for conditions that are incorrect for the commanded state. If the ECM detects an improper circuit condition, START relay DTC P0615 will set.
You need to find out which relay is clicking . run/crank or start relay . Do you know how to test computer controlled relays ?
Here's a video on testing a computer controlled fuel pump relay , same as the start relay or any GM PCM controlled relay .
DTC P1631 Theft Deterrent Fuel Enable Signal Not Correct
The powertrain control module (PCM) controls the fuel injector operation and the starter operation based on a vehicle theft deterrent (VTD) password from the vehicle body control module (BCM). When the ignition is first turned ON, the BCM sends a programmed theft deterrent password to the PCM. The PCM acknowledges the password and responds to the BCM that normal fuel injector and starter operation will continue. If the PCM detects an incorrect password, a theft deterrent system failure, or an attempted vehicle theft, DTC 1631 will set. The engine will not start or crank as long as the condition is present.
Diagnostic Aids
DTC P1631 indicates that the vehicle theft deterrent password that the PCM has learned does not agree with the password received from the VTD system. This condition can occur if the BCM has been replaced and the PCM Password Learn function has not been enabled. If the BCM has been replaced, the password must be relearned.
Step
Action
Yes
No
1
Did you perform the Diagnostic System Check - Vehicle?
Go to Step 2
Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2
Perform the Password Learn Procedure. Refer to Programming Theft Deterrent System Components .
Did you complete the procedure?
System OK
30-Minute Learn Procedure
Turn ON the ignition, with the engine OFF.
Attempt to start the engine, then release the key to ON; the vehicle will not start.
Observe the SECURITY telltale. After approximately 10 minutes, the telltale will turn OFF.
Turn OFF the ignition, and wait 5 seconds.
Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes. The vehicle is now ready to relearn the Passlock™ Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK.
Important: The vehicle learns the Passlock™ Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.
Start the engine. The vehicle has now learned the Passlock™ Sensor Data Code and/or password.
With a scan tool, clear any DTCs if needed. History DTCs will self clear after 100 ignition cycles.
Did you test the electrical circuit's ? Have a scan tool hooked up ? Did you have a qualified repair shop check it out ?
When the engine is running, the generator control signal is sent to the generator from the engine control module (ECM)/powertrain control module (PCM), turning on the regulator. The generator's voltage regulator controls current to the rotor, thereby controlling the output voltage. The rotor current is proportional to the electrical pulse width supplied by the regulator. When the engine is started, the regulator senses generator rotation by detecting AC voltage at the stator through an internal wire. Once the engine is running, the regulator varies the field current by controlling the pulse width. This regulates the generator output voltage for proper battery charging and electrical system operation. The generator F terminal is connected internally to the voltage regulator and externally to the PCM. When the voltage regulator detects a charging system problem, it grounds this circuit to signal the PCM that a problem exists. The PCM monitors the generator field duty cycle signal circuit. The system voltage sense circuit receives B+ voltage that is Hot At All Times through the ECM/TCM fuse in the underhood junction block. This voltage is used by the regulator as the reference for system voltage control.
This vehicle uses Class II and controller area network (CAN) communications. The ECM/PCM are CAN and the body controller systems are Class II. The body control module (BCM) acts as the gateway between the different communication protocols. The ECM/PCM requests the battery lamp on the CAN communication line and then the BCM sends a request to the IPC for lamp illumination.
The ECM/PCM will request the battery lamp on under the following conditions:
• The ECM/PCM interprets the ignition is in the accessory position.
• The ECM/PCM is in the RUN power mode with the engine not running.
• Generator L terminal fault has been detected.
• Generator F terminal fault has been detected.
If the generator is not charging, it pulls the F terminal low causing an F terminal fault. Low voltage threshold is 10.5 volts for 4 minutes and engine at least 1,300 RPM. High threshold is 18 volts for 5 minutes.
Do you know what DTC'S diagnostic trouble codes are ?
DTC B1325
DTC B1327
DTC B1328
DTC P0562
DTC P0563
DTC P0615
DTC P0621
DTC P0622
These are all for the charging system .
You need a capable scan tool to check DTC'S - diagnostic trouble code's .
DTC B2734
DTC B2960
DTC B3031
DTC B3055
DTC P1630
DTC P1631
These would tell why the PCM - engine computer isn't starting the vehicle . There is no by-pass for this anti-theft system . The Dealer is your only hope . Nothing you can do !
The theft deterrent control module produces the theft deterrent fuel and starter enable signal when ignition is ON and the proper transponder key value is detected. The powertrain control module (PCM) monitors the fuel and starter enable signal during crank. If the proper signal is present on the Class 2 Serial Data Circuit, the PCM enables the fuel delivery and starter operation in order to allow the engine to start. If the PCM detects an incorrect password, vehicle theft deterrent (VTD) system failure or attempted vehicle theft, DTC P1631 is set. The engine will not start or crank as long as the condition is present.
What's wrong with it , have you had it checked for DTC'S - diagnostice trouble codes .
The design of the passlock™ system is to prevent the vehicle operation if the proper ignition key is not used in order to start the vehicle. The mechanical key, in normal operation, will turn the passlock™ lock cylinder. The passlock™ sensor will relay the passlock™ data to the body control module (BCM). The BCM will determine the validity of the passlock™ data. The BCM will send a code password to the vehicle/powertrain control module (VCM/PCM). When the VCM/PCM receives the correct code the VCM/PCM allows the fuel injectors to operate normally. The passlock™ system requires the VCM/PCM and the BCM to communicate the various functions in order to operate. These functions transmit over the class 2 serial data line CKT 1807. For an explanation of the class 2 serial data operation refer to Data Link Connector Circuit Description in Wiring Systems.
Telltale Indication
Condition
ON constant for 3 seconds, then OFF
The bulb check occurs upon power-up (Ignition 1 and crank).
ON constant for 3 seconds, OFF momentarily, ON constant/ignition OFF
DTC (current) is set with the ignition ON (see DTC B2947, B2948, B2957 and B2958).
ON constant/ignition OFF
The TBC fuse is open or an open in CKT 1140
ON constant for 3 seconds, FLASH for 10 minutes, then OFF
Occurs when a Passlock™ sensor has been replaced and the ignition switch has been turned from the OFF position to the CRANK position. This sequence occurs 3 times.
FLASH with the ignition ON
The Passlock system is in a tamper mode (see DTC B2960 and B3033).
ON constant for 3 seconds, OFF momentarily, then ON constant for 10 minutes, then OFF
Occurs when a new BCM or a new PCM/VCM has been installed, and the ignition switch has been turned from the OFF position to the CRANK position. This sequence occurs 3 times.
ON constant for 3 seconds, OFF for 2 seconds, then ON constant
The IPC is unable to communicate with the BCM.
DTC B2947 Security System Sensor Power CKT Low
DTC B2948 Security System Sensor Power CKT High
DTC B2957 Security System Sensor Data Circuit Low
DTC B2958 Security System Sensor Data Circuit High
DTC B2960 Sec Sys Sensor Data Incorrect but Valid
DTC B3031 Security System Controller in Learn Mode
DTC B3033 Security System Indicates Tamper .
Your best bet , take your vehicle to a qualified repair shop .
If the light is on there are code stored ! Not in the PCM/ECM engine computer . In the BCM , do you know what that is ? body control module ! Need a factory scan tool or equivalent to check !
DTC B0688 Security System Indicator Circuit High
DTC B2947 Security System Sensor Power CKT Low
DTC B2948 Security System Sensor Power CKT High
DTC B2957 Security System Sensor Data Circuit Low
DTC B2958 Security System Sensor Data Circuit High
DTC B2960 Sec Sys Sensor Data Incorrect but Valid
DTC B3031 Security System Controller in Learn Mode
DTC B3033 Security System Indicates Tamper
DTC C0559 EEPROM Checksum Error
Why does everyone want to chop up things , by pass etc... The right fix could be cheaper then ruining your vehicle . Chopping up wiring harnesses . Their are by pass module , don't know how much they are . It may or may not fix the problem . Pulling the code and doing the diagnostics is still the best solution .
Having the vehicle checked for codes should have been the first thing done . Security light on ,a code is stored in the control module that controls the anti-theft system ! This is if you want it fixed right !
Important: If the wrong ignition key is used in an attempt to start the vehicle, a Data Trouble Code (DTC) will be set and the Body Control Module (BCM) will not send a fuel enable or starter enable message to the Powertrain Control Module (PCM) for three minutes even if the correct ignition is used.
The Pass-Key II® Theft Deterrent system prevents vehicle theft by disabling the starter motor and fuel system. If the Body Control Module (BCM) dose not identify the use of the correct ignition key to start the vehicle, the (BCM) will communicate a message to the Powertrain Control Module (PCM) which will disable the crank relay and fuel delivery to the engine.
When the (BCM) identifies the use of the correct ignition key (resistor pellet) to start the vehicle, the (BCM) will send a fuel enable and starter enable message to the (PCM) which will allow the vehicle to start.
DTC B2957 Security System Sensor Data Circuit Low
DTC B2958 Security System Sensor Data Circuit High
DTC B2960 Sec Sys Sensor Data Incorrect but Valid
DTC B3031 Security System Controller in Learn Mode
DTC B3094 No Response from ECM/PCM Received
or you can do a by pass that may or may not work ! You could measure the resistance of the pellet on the side of the key , then go to radio shack a by a resistor of the same value ! Then find the wires under the dash that come from the ignition switch ! Solder the resistor into the harness side wires , not going back to ignition switch . The wires break or contacts inside ignition switch do . You could check resistance with ohm meter . Put key into the ignition switch , find those wires i said about before . Check resistance at the wires under dash , is it the same resistance as pellet ?
Do you have a second key ?
Passlock™ System
The theft deterrent system has been incorporated into the body control module (BCM). The theft deterrent is provided in order to prevent vehicle operation if the correct key is not used in order to start the vehicle. The ignition key turns the 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)/vehicle control module (VCM). The message enables the fuel injectors.
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 PASS-Key® 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 BCM
• The security telltale
• The VCM/PCM
Your best bet , take it to a qualified repair shop . Security light on - DTC'S - diagnostic trouble codes are stored . Having codes check would point in a diagnostic procedure to fix the issue .
DTC B2947
DTC B2948
DTC B2957
DTC B2958
DTC B2960
DTC B3031
DTC B3033
DTC P1626
DTC P1631
Circuit Description
The Passlock™ system is provided in order to prevent vehicle theft if the ignition lock cylinder is forced to rotate or the ignition switch is operated while separated from the ignition lock cylinder case. The body control module (BCM) provides security system sensor power and low reference for the Passlock™ sensor. The BCM also measures the security system sensor voltage.
When the correct key is used to start the vehicle, a magnet on the lock cylinder passes close to the Passlock™ sensor within the ignition lock cylinder case. The magnet activates the security hall effect sensor in the Passlock™ sensor which completes a circuit from the security sensor signal circuit through a resistor to the security sensor low reference circuit. The resistance value will vary from vehicle to vehicle. The BCM will measure the voltage on the security sensor signal circuit and compare this voltage to a previously learned voltage. If the voltage measured is within the valid range, the BCM will send a class 2 message to the powertrain control module (PCM) to enable vehicle starting. If the voltage measured is not within the valid range, a class 2 message will be sent to the PCM to disable starting of the vehicle.
Start with looking at scan data on a scan tool , not a code reader
If the PCM detects a MAP sensor signal voltage that is excessively low, DTC P0107 will set.
The PCM calculates a predicted value for the MAP sensor based on throttle position and engine speed. The PCM then compares the predicted value to the actual MAP sensor signal. DTC P0106 will set if the MAP sensor signal is not within the predicted range.
This does not mean the sensor is bad ,could be a wiring problem ,computer etc....
P0306 is a misfire on cylinder # 6 This would be a good one to start with , could ruin the CAT .
The powertrain control module (PCM) uses dual crankshaft position (CKP A and CKP B) sensors in order to determine crankshaft position.
If the PCM determines that CKP sensor A is at fault, DTC P0335 will set. The PCM will switch from angle based mode to Time Based mode B using CKP sensor B signal input.
Diagnostic Aids
If the condition is intermittent, refer to Intermittent Conditions in Symptoms.
Ignition system DTCs set with the ignition in the START position if the starter relay or the starter is inoperative. When the PCM enables starter operation, the PCM also initiates the diagnostic test routines for DTCs P0335, P0340, and P0385. The PCM will not receive signal input from the CKP and CMP sensors if a condition exists which prevents the engine from cranking. When this occurs, the DTCs will set.
If DTC P0615 is set, diagnose DTC P0615 first. If DTC P0335, P0340, and/or P0385 are set and no trouble is found, check for the following conditions:
• Is there a no-crank condition or an intermittent no-crank condition?
• Was an attempt made to crank the engine with the shift lever not in P/N?
Procedures for Selecting Crank Position Sensing Decode Mode
Diagnosing the crankshaft position sensors may require enabling a specific decode mode (Angle, Time A, or Time B). To enable a specific crank decode, using the scan tool, perform the following steps:
• Turn the ignition to the RUN/ON position.
• Select Engine Output Controls.
• Select Crank Position Sensing Decode Mode.
• Select the desired mode (Angle, Time A, or Time B) by pressing SELECT STATE.
• Command the decode mode by pressing COMMAND STATE.
The commanded state remains valid for the current ignition cycle. A specific decode mode can not be commanded with the engine running, or after commanding a desired decode mode. To command a different decode mode, you must cycle the ignition OFF and ON.
DTC P0385
The PCM uses two basic methods of decoding the engine position: Angle Based and Time Based (using either CKP A or CKP B sensor input). During normal operation, the PCM uses the angle based method. In order to operate in this mode, the PCM must receive signal pulses from both CKP sensors. The PCM uses the signal pulses to determine an initial crankshaft position, and to generate MEDRES (24X reference) and LORES (4X reference) signals. Once the initial crank position is determined, the PCM continuously monitors both sensors for valid signal inputs. As long as both signal inputs remain, the PCM will continue to use the angle based mode.
When either CKP signal is lost, the PCM will compare the MEDRES signal to the camshaft position (CMP) sensor signal. If the PCM detects a valid CMP signal, and the MEDRES to CMP signal correlation is correct, the PCM determines that CKP sensor A is at fault. However, if the MEDRES to CMP correlation is incorrect, the PCM determines that CKP sensor B is at fault. If the PCM determines that CKP sensor B is at fault, DTC P0385 will set. The PCM will switch from angle based mode to Time Based Mode A using CKP sensor A signal input.
DTC P0410
Circuit Description
The secondary air injection (AIR) pump used on this vehicle lower tail pipe emissions during start-up. The AIR system consists of the following items:
• The AIR pump
• The shut-off valves
• The vacuum control solenoid valve
• The system hoses and piping
• The AIR relay, the fuses, and the related wiring
The powertrain control module (PCM) uses the AIR relay in order to control the AIR pump. The PCM also controls the AIR vacuum control solenoid valve that supplies vacuum to the AIR shut-off valves. With the AIR system inactive, the AIR shut-off valves prevent air flow in either direction. With the AIR system active, the PCM applies ground to the AIR relay, and the vacuum control solenoid valve. Fresh air flows from the pump, through the system hoses, past the shut-off valves, and into the exhaust stream. The air helps the catalyst quickly reach normal working temperature; thus lowering the tail pipe emissions on a start-up. The PCM tests the AIR system for the following conditions:
• AIR System (Overall system including both banks, and results in DTC P0410)
• AIR System Bank 1 (DTC P1415)
• AIR System Bank 2 (DTC P1416)
• AIR Relay (DTC P0418)
• AIR Vacuum Control Solenoid (DTC P0412)
The PCM runs two tests to diagnose the AIR system: Passive, and Active. Both tests involve a response from the fuel control HO2 sensors (HO2S Bank 1 Sensor 1 and HO2S Bank 2 Sensor 2). If both passive tests pass, the PCM takes no further action. If either part of the passive test fails, or is inconclusive, the PCM initiates the Active tests. If the PCM determines that the HO2S voltages did not respond as expected during the tests, the DTC will set. For further information concerning the AIR System and system tests, refer to
DTC P0506 DTC P0507
The idle air control (IAC) valve is located in the throttle body. The IAC valve consists of a movable pintle, driven by a gear attached to an electric motor called a stepper motor. The IAC valve motor is a 2-phase bi-polar permanent magnet stepper motor that is capable of highly accurate rotation, or movement, every time the polarity of a winding is changed. This change in polarity can be seen when observing a test lamp connected between ground or B+ and an IAC valve circuit while the powertrain control module (PCM) is attempting to change engine RPM. The test lamp will flash on or off each time the polarity is changed. The PCM does not use a physical sensor to determine IAC pintle position, but uses a predicted number of counts, one count represents one change in polarity which equals one step of the stepper motor. The PCM counts the steps that have been commanded in order to determine the IAC pintle position. The PCM uses the IAC valve to control engine idle speed by changing the pintle position in the idle air passage of the throttle body. This varies the air flow around the throttle plate when the throttle is closed. In order to determine the desired position of the IAC pintle at idle or during deceleration, the PCM refers to the following inputs:
Important: Ensure that the engine speed stabilizes with each commanded RPM change in order to determine if engine speed stays within 100 RPM of the commanded RPM.
Set the parking brake, and block the drive wheels.
Install a scan tool.
Start the engine.
Turn OFF all the accessories.
With the scan tool RPM control function, slowly increment engine speed to 1,700 RPM, then to 600 RPM, then to 1,800 RPM.
Exit the RPM control function.
Does the engine speed stabilize within 100 RPM of the commanded RPM during the above test?
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