I appologize for posting a Caddy question here, but it is my last resort. Can anyone help me with a Caddilac problem? After being parked for 5 min it will only turn and not start. There is gas. Also, the security light stays on even after key is left on for 20 min plus. Any help on this would be greatly appreciated. -Tony

 

Here is a diagnostic but I doubt it will help much since you can't see the codes like you can on a C5. The BCM could be involved and an autoparts store scanner will not see any of those codes although it won't hurt to see if there are any PCM codes.
Engine Cranks but Does Not Run

Description


The Engine Cranks but Does Not Run diagnostic table is an organized approach to identifying a condition that causes an engine to not start. The diagnostic table directs the service technician to the appropriate system diagnosis. The diagnostic table assumes the following conditions are met:

• The battery is completely charged. Refer to Battery Inspection/Test in Engine Electrical.
• The engine cranking speed is within specification. Refer to Engine Cranks Slowly in Engine Electrical.
• There is adequate fuel in the fuel tank.

Diagnostic Aids


Inspect for the following conditions:

• The mass air flow (MAF) is compared to a calculated MAF based upon the manifold absolute pressure (MAP), the throttle position (TP), and the engine RPM. A skewed or unresponsive MAP sensor at key ON will cause the predicted air flow value to be inaccurate. Compare the MAP and TP readings to that of a known good vehicle.
• Inspect for a faulty engine coolant temperature (ECT) sensor. Use a scan tool in order to compare the ECT with the intake air temperature (IAT) on a completely cooled engine. The ECT should be within 3°C (5°F) of the IAT.
• For an intermittent condition, refer to Intermittent Conditions .

Test Description


The numbers below refer to the step numbers on the diagnostic table.

1. You may need to connect a battery charger to the battery for this step. If the battery state of charge is low, the scan tool may reset during the cranking test.
   
2. This step tests the ignition relay for proper operation. The ignition relay supplies voltage to the injectors and the ignition coils. When the ignition relay is not operating properly, a no start condition occurs. If the test lamp does not illuminate, this indicates the ignition relay is not suppling a voltage to the fuses.

Step
Action
Values
Yes
No
Schematic Reference: Engine Controls Schematics
1
Did you perform the Diagnostic System Check-Engine Controls?
--
Go to Step 2
Go to Diagnostic System Check - Engine Controls
2
Crank the engine for the specified amount of time.
Does the scan tool display any DTCs that failed this ignition?
15 seconds
Go to Diagnostic Trouble Code (DTC) List
Go to Step 3
3
Inspect the body control module (BCM) for DTCs related to the vehicle theft deterrent (VTD) system.
Does the scan tool display any BCM VTD DTCs?
--
Go to Diagnostic System Check - Theft Deterrent in Theft Deterrent
Go to Step 4
4
Monitor the engine speed while cranking the engine.
Is engine RPM indicated on the scan tool?
--
Go to Step 5
Go to Electronic Ignition (EI) System Diagnosis
5

1. Turn ON the ignition, with the engine OFF.
2. Probe both sides of the fuses located in the underhood electrical center listed below using a test lamp connected to ground.
   • INJR A
   • INJR B
   • ECM I

Does the test lamp illuminate on both sides of the fuses?
--
Go to Step 6
Go to Ignition Relay Diagnosis
6
Monitor the engine coolant temperature (ECT) using the scan tool.
Is the ECT on the scan tool close to the actual engine temperature?
--
Go to Step 7
Go to DTC P0118
7
Enable the fuel pump using the scan tool.
Does the fuel pump operate?
--
Go to Step 8
Go to Fuel Pump Electrical Circuit Diagnosis

8

1. Turn OFF the ignition.
2. Install a fuel pressure gauge. Refer to Fuel System Diagnosis . Important
   
   The fuel pump operates for about 2 seconds when the ignition is turned ON. The fuel pressure must be observed when the fuel pump is operating.
   
   
3. Turn ON the ignition, with the engine OFF.
4. Observe the fuel pressure while the fuel pump is operating.

Is the fuel pressure within the specified range?
VIN V,T, U Gasoline: 385-425 kPa (55-62 psi)
VIN Z Ethanol: 335-375 kPa (48-54 psi)
Go to Step 9
Go to Fuel System Diagnosis
9

Perform the following additional inspections:

• Inspect the duct work between the MAF sensor and the throttle body for air leaks.
• Inspect that the throttle angle is at 0 percent at a closed throttle. If the throttle angle is not at 0 percent , refer to DTC P0122 or DTC P0123 .
• A malfunctioning MAF sensor may cause a no start or a stall after a start. If you suspect this, disconnect the MAF sensor. The PCM will default to the speed density in order to calculate the engine load and the intake air flow. If disconnecting the MAF sensor corrects the condition and the connections are OK, replace the MAF sensor. Refer to Mass Air Flow (MAF)/Intake Air Temperature (IAT) Sensor Replacement .
• Inspect the spark plugs for being gas fouled. Refer to Spark Plug Inspection in Engine Electrical.
• Inspect for an engine mechanical failure that causes an engine not to start such as timing chain, low compression. Refer to Engine Compression Test in Engine Mechanical 4.8L, 5.3L, 6.0L.
• Compare the MAP/BARO parameters to another vehicle. The parameter values should be close to each other.

Did you find and correct the condition?
--
Go to Step 10
Go to Hard Start

10

1. Select the Diagnostic Trouble Codes (DTC) option and the Clear DTC Information option using the scan tool.
2. Attempt to start the engine.

Does the engine start and continue to run?
--
Go to Step 11
Go to Step 2

11

1. Idle the engine at the normal operating temperature.
2. Select the Diagnostic Trouble Code (DTC) option using the scan tool.

Are any DTCs displayed?
--
Go to Diagnostic Trouble Code (DTC) List
Go to Step 12
12
Select the Capture Info option and the Review Info option using the scan tool.
Are any DTCs displayed that you have not diagnosed?
--
Go to Diagnostic Trouble Code (DTC) List
System OK


Bill

 

Bill,That helps greatly. Also, I got a friend to hook up his scanner but the OBDII port is dead on the truck. It wont turn on the scanner. Any ideas?-Tony

 

There are several possibilities. The fact the security light stays lit indicates there is a problem with the theft deterrent system which is part of the BCM. I am including a description of how the theft deterrent system works. If not working properly it might could cause a the engine to crank but not start.

Vehicle Theft Deterrent (VTD) Description and Operation


The vehicle theft deterrent (VTD) system functions are provided by the theft deterrent control module. When an ignition key is inserted into the ignition lock cylinder and the ignition is switched ON, the transponder embedded in the head of the key is energized by the exciter coils surrounding the ignition lock cylinder. The energized transponder transmits a signal that contains its unique value, which is received by the theft deterrent control module. The theft deterrent control module then compares this value to a value stored in memory, learned key code. If the value is correct the theft deterrent control module sends a random generated number to the transponder, this is called a challenge. Both the transponder and the theft deterrent control module perform a calculation on the challenge, if the calculations match the theft deterrent control module sends the fuel enable password via the serial data circuit to the powertrain control module (PCM). If either the transponders unique value or the calculation to the challenge is incorrect the theft deterrent control module will send the fuel disable password to the PCM via the serial data circuit. The components of the VTD system are as follows:

• Theft deterrent control module
• Powertrain control module (PCM)
• Ignition key (Transponder)
• Ignition lock cylinder
• Security indicator

Theft Deterrent Control Module

Vehicles with steering column mounted ignition switches have the exciter integral with the theft deterrent control module which is located within the steering column. Vehicles with instrument panel mounted ignition switches have exciter modules separate from the theft deterrent control module with the vehicle wiring harness connecting the two. The theft deterrent control module for vehicles with instrument panel mounted ignition switches is located within the instrument panel. The theft deterrent control module can learn up to ten keys (transponder values).
The theft deterrent control module uses the following inputs, battery voltage, ignition switched voltage and ground circuit. The theft deterrent control module uses the following outputs, password exchange with the PCM, fuel enable/disable via the serial data circuit.

When an ignition key is inserted into the ignition lock cylinder and the ignition is switched ON, the transponder embedded in the head of the key is energized by the exciter coils surrounding the ignition lock cylinder. The energized transponder transmits a signal that contains its unique value, which is received by the theft deterrent control module. The theft deterrent control module then compares this value to a value stored in memory, learned key code. If the value is correct the theft deterrent control module sends a random generated number to the transponder, this is called a challenge. Both the transponder and the theft deterrent control module perform a calculation on the challenge. The theft deterrent control module then performs one of the following functions:

• If both the transponder value and the calculation to the challenge are correct, the theft deterrent control module will send the fuel continue password to the PCM via the serial data circuit.
• If either the transponders unique value or the calculation to the challenge is incorrect the theft deterrent control module will send the fuel disable password to the PCM via the serial data circuit.
• If the theft deterrent control module is unable to measure the ignition key transponder value for one second due to a damaged or missing pellet or a damaged exciter, the theft deterrent control module will send the fuel disable password to the PCM via the serial data circuit.

Powertrain Control Module (PCM)

The PCM verifies that the password received from the theft deterrent control module via the serial data circuit is correct. The PCM can learn only one fuel continue password. If the fuel continue password is correct, the PCM enables the starting and fuel delivery systems.

The PCM disables the starting and fuel delivery systems if any of the following conditions occur:

• The fuel continue password is incorrect.
• The fuel disable password is sent by the theft deterrent control module.
• No passwords are received - there is no communication with the theft deterrent control module.

The Ignition Key (Transponder)

The ignition key on vehicles equipped with the passkey III+ system is a typical looking ignition key with a transponder located in the plastic end of the key. The transponder value is fixed and unable to be changed. The VTD system uses the ignition key transponder value to determine if a valid ignition key is being used to start the vehicle. There are approximately three trillion possible transponder values. There are no visible electrical contacts. The keys may be identified by the letters PK3+ stamped into the steel shank of the key. The VTD systems use the following types of ignition keys:
Master Keys

Master keys have a black plastic end are for full access operation of the vehicle. Master keys may perform the following functions:

• Start the vehicle.
• Lock/unlock all of the door locks.
• Lock/unlock all of the storage compartments.

Ignition Lock Cylinder

The ignition lock cylinder performs all of the functions of a lock cylinder on a non PK3+ equipped vehicle. The ignition lock cylinder for vehicles with PK3+ may be located on the steering column or on the instrument panel. In either location the exciter coils surround the ignition lock cylinder such that they are very close to the head of the key which contains the transponder pellet.
If an ignition lock cylinder is replaced, the PK3+ keys must match the mechanical coding of the new lock cylinder. When replacing an ignition lock cylinder, and new PK3+ keys are required, refer to Programming Theft Deterrent System Components .
SECURITY Indicator Operation

The theft deterrent control module can command the instrument cluster to illuminate the SECURITY indicator only when the ignition key is in the ON position. If the PCM loses communication with the theft deterrent control module, the instrument cluster will also detect the loss of communication and will illuminate the SECURITY indicator. The SECURITY indicator can indicate both malfunctions, Indicator on steady and tamper, Indicator flashing. A flashing indicator indicates unauthorized operation. Under the following conditions the SECURITY indicator may be commanded to illuminate.
SECURITY Indicator Illuminates when Engine is Running
If the theft deterrent control module is unable to measure the ignition key transponder value or the PCM loses communication with the theft deterrent control module while the engine is running, the indicator will be illuminated.
SECURITY Indicator Illuminated and Engine Does Not Start
If the theft deterrent control module was unable to measure the ignition key transponder value or the PCM has detected a problem with the theft deterrent system. The VTD system is in Learn Mode. Refer to Programming Theft Deterrent System Components .
SECURITY Indicator Flashes and Engine Does Not Start
The theft deterrent control module has measured an incorrect transponder value, the calculation to the challenge is incorrect or the PCM has lost communication with the theft deterrent control module, The VTD system considers this a tamper condition. The VTD indicator will flash.

The fact the scanner cannot talk to the data link (OBD) might indicate your BCM has a problem or there is a problem with the serial datalink. Another possibility is the scan tool you used may not be able to pull all of the codes available.


Bill

 

If some work was done on the vehicle such as replacing the PCM you may need to resynch the PCM with the system. Here is how that is done. A Tech II is required.

Programming Theft Deterrent System Components


Important

When replacing a theft deterrent control module with a GM Service Parts Operation (SPO) Replacement Part, the procedure to setup a new theft deterrent control module must be performed prior to the 10 Minute Re-Learn Procedure.

Tools Required

Tech 2 diagnostic scan tool
Procedure to setup a New Theft Deterrent Control Module


Use this procedure only if replacing the theft deterrent control module with a GM Service Parts Operation (SPO) Replacement Part.

1. Connect the Tech 2 diagnostic scan tool to the vehicle.
2. Turn ON the ignition , with the engine OFF.
3. With the scan tool, select Setup New VTD Module in the Vehicle Theft Deterrent, Special Functions data list.
4. Follow the scan tool on screen instructions.

Important

• When replacing a theft deterrent control module with a GM Service Parts Operation (SPO) Replacement Part, the module will learn keys immediately. The existing PCM however, must learn the new fuel continue password when the theft deterrent control module is replaced.
• When replacing a powertrain control module (PCM) with a GM Service Parts Operation (SPO) Replacement Part, after programming, these modules will learn the incoming fuel continue password immediately upon receipt of a password message. Once a password message is received, and a password is learned, a relearn procedure must be performed to change this password again. A PCM which has been previously installed in another vehicle will have learned the fuel continue password of the other vehicles theft deterrent control module and will require performing the 10 Minute Re-Learn Procedure to learn the fuel continue password of the current vehicles theft deterrent control modules .
• When performing the 10 Minute Re-Learn Procedure, all previously learned keys will be erased from the theft deterrent control module's memory.
• Additional keys may be learned immediately after the 10 Minute Re-Learn Procedure. Refer to Adding Keys .
• When performing the 10 Minute Re-Learn Procedure, 2 master passkey III+ (PK3+) keys are required. If a gray valet key is learned first, the theft deterrent control module will not allow additional keys to be learned.

Tools Required

• Tech 2 diagnostic scan tool
• Techline Terminal with current Service Programing System (SPS) software

10 Minute Re-Learn Procedure


Use this procedure after replacing any of the following components:

• The passkey III+ (PK3+) keys
• The theft deterrent control module
• The PCM, see Important above

Important

If replacing a theft deterrent control module with a GM Service Parts Operation (SPO) Replacement Part, insure the procedure to setup a new theft deterrent control module has been performed prior to the 10 Minute Re-Learn Procedure.

1. Connect the Tech 2 diagnostic scan tool to the vehicle.
2. With the scan tool, select Request Info. under Service Programing System and follow the scan tool on screen instructions.
3. Disconnect the scan tool from the vehicle and connect it to a Techline Terminal with current Service Programing System (SPS) software.
4. On the Techline Terminal, select Service Programming Systems and follow the Techline Terminal on screen instructions.
5. Disconnect the scan tool from the Techline Terminal and re-connect it to the vehicle.
6. With a master passkey III+ (PK3+) key, turn ON the ignition, with the engine OFF.
7. With the scan tool, select Program ECU under Service Programing System.
8. At this point the scan tool must remain connected for the duration of the 10 Minute Re-Learn Procedure.
9. Observe the SECURITY telltale or the scan tool on screen timer, after approximately 10 minutes the scan tool timer will expire and/or the telltale will turn off. The vehicle is now ready to relearn the key information and/or passwords on the next ignition switch transition from OFF to CRANK.
10. Turn OFF the ignition and wait 5 seconds.
11. With a master passkey III+ (PK3+) key, start the vehicle, the theft deterrent control module has now learned the key transponder information and the PCM has now learned the fuel continue password.
12. Turn OFF the ignition and wait 15 seconds minimum.
13. With a second master passkey III+ (PK3+) key, start the vehicle, the theft deterrent control module has now learned the second master passkey III+ (PK3+) key transponder information.
14. Learning Additional keys, if required. Refer to Adding Keys .
15. With the scan tool, clear any DTCs.

Bill

 

Thank you so much. I will try these steps and post my findings.-Tony

 

Update-----After trying the above recomendations as best I could, I gave it to a GM mech that does side work....He found a bad ECU (Eng Contr Unit). Its being replaced now. Thanks again Bill.

 

Post #5 is not completely correct

Swapping PCM, you can do a 3 cycle key on/off to sync a pcm to bcm, I've done this, it works w/out tech2