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My husband has a 2008 Chevy Silverado and he is sitting in a parking lot with the Theft Deterrant light flashing and it will not start. There is no horn going off or anything.. it just wont start. He has already made sure all the fuses are connected properly.. but still nothing.. please help..

Submitted: 53 days and 13 hours ago.
Category: Chevy
Value: $9
Status: AWAITING CUSTOMER ACTION
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Optional Information

Year : 2008
Make : Chevrolet
Make (other) : Silverado
Engine : allison

Already Tried:
making sure all fuses are connected

Posted by Butch 53 days and 13 hours ago.

Info Request

Hi XXXXXXXXX,

 

Is the light flashing continuously with the key turned to the run position for more than 10 seconds? Does it have a diesel engine?

 

Butch



Edited by Butch on 9/30/2009 at 11:40 PM

53 days and 13 hours ago.

Reply

Yes and yes!~

Posted by Butch 53 days and 13 hours ago.

Info Request

Not to sound persistant, but problems with the theft systems are rare. If he leaves the key in the run position for 10-15 seconds is the light still flashing?

53 days and 13 hours ago.

Reply

one second... He turns the key to on.. it says Theft Deterrant System but it is not flashing just constantly on and wont turn over.

Posted by Butch 53 days and 12 hours ago.

Info Request

The theft deterrent will not disable the starter, it disables the fuel. If the engine will not turn over, and the theft light stays on, then you may have more than one problem. I have seen a few that would turn over but not run that simply lost prime. A couple pumps on the primer and all was good. The only thing with diesels that I have seen cause it to not even turn over, is the starter, but even that is rare. I looked for any service bulletins that would apply to this, but I don't see any. Do you have access to a test light or multi-meter? If so, we can determine if it is a theft problem, or a starter problem.

53 days and 12 hours ago.

Reply

He informed me that it will act like it will start but then shuts down. It rolls over two or three times and then quits. His phone number is XXX-XXX-XXXX If you could PLEASE call him.. he is sitting in a parking lot without any one to help him. He could use the help instead of me relaying information.

Accepted Answer

They will not let phone number come through our system like that.... If the engine does turn over but only a couple times and then quits, then his battery is probly just weak and a jump start should get him going. If he gets someone to jump it for him, let it charge for at least 5 minutes before cranking it. It has 2 batteries in it and takes quit a bit of power to turn it over. If you can get it to turn over quickly and it still will not run, try pumping the prime on top of the fuel filter until it gets hard, then try cranking it again. If there is a problem with the theft deterrent, the engine should run for about 2 seconds and then shut off.

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Expert: Butch
Pos. Feedback: 100.0 %
Accepts: 
Answered: 10/1/2009

Master ASE Certified Technician

Master ASE Certified Technician, 10 years experience, 60+ GM certificates, 150+ GM training courses

53 days and 12 hours ago.

Reply

Thanks for trying. He still thinks it is Theft Deterrant related.. because it has not been exhibiting any battery sluggishness or anything. It is not cold here yet to cause the weather to drain it.. etc. So thank you anyway.. you tried!

Posted by Butch 53 days and 12 hours ago.

Answer

Read this, it is how and what the theft deterrent does. I still think you need to try jumping it, that is unless it is dead due to repeated tries to start it.

 

 

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2008 Chevrolet Silverado - 2WD | Sierra, Silverado (VIN C/K) Service Manual | Document ID: XXXXXXX


Immobilizer Description and Operation

The immobilizer system functions are provided by the theft deterrent module (TDM) and the engine control module (ECM). 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 coil surrounding the ignition lock cylinder. This exciter coil is part of the TDM. The energized transponder transmits a signal that contains its unique value, which is received by the TDM. The TDM then compares this value to a value stored in memory. If the values match, the TDM will send the prerelease password via the serial data circuit to the ECM. If the transponders unique value is incorrect, the TDM will send the fuel disable password to the ECM.

When the ECM receives the TDM prerelease password, the ECM will challenge the password. The ECM sends this challenge back to the TDM via the serial data circuit. Both the ECM and TDM perform a calculation on this challenge. If the calculated response from the TDM equals the calculation performed by the ECM, the ECM will allow vehicle starting.

The components of the theft system are as follows:

• TDM
• ECM
• Ignition key (Transponder)
• Security indicator

Theft Deterrent Module (TDM)

Vehicles with steering column mounted ignition switches have the exciter integral with the theft deterrent module (TDM), which is located within the steering column. The TDM can learn up to 10 keys (transponder values).

The TDM uses the following inputs:

• Battery voltage
• Ignition switched voltage
• Ground circuit

The theft deterrent control module uses the following outputs:

• Password exchange
• Challenge/response with the engine control module (ECM)

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 TDM. The TDM then compares this value to the learned key code stored in memory. The TDM then performs one of the following functions:

• If the transponder value matches the values stored in the TDM memory, the TDM will send the prerelease password to the ECM via the serial data circuit.
• If the transponders unique value does not match the value stored in the TDM, the TDM will send the fuel disable message to the ECM via the serial data circuit.
• If the TDM is unable to measure the ignition key transponder value, the TDM will not send any messages to the ECM.

Engine Control Module (ECM)

When the engine control module (ECM) receives the theft deterrent module (TDM) prerelease password, the ECM will challenge the password. The ECM sends this challenge back to the TDM via the serial data circuit. Both the ECM and TDM perform a calculation on this challenge. If the calculated response from the TDM equals the calculation performed by the ECM, the ECM will allow vehicle starting.

The ECM will disable vehicle starting if any of the following conditions occur:

• The prerelease password is invalid.
• The fuel disable password is sent by the TDM.
• No passwords are received. There is no communication with the TDM.
• The TDM calculated response to the challenge does not equal the calculation performed by the ECM.

The Ignition Key (Transponder)

The ignition key for PassKey III+ (PK3+) equipped vehicles is a standard ignition key with a transponder located in the plastic head of the key. The transponder value is fixed and unable to be changed. The immobilizer system uses the ignition key transponder value to determine if a valid ignition key is being used to start the vehicle. There are approximately 3 trillion possible transponder values. There are no visible electrical contacts. The keys are identified by + symbol in a circle stamped into the steel shank of the key. The immobilizer system use the following types of ignition keys:

Master Keys

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

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

Valet Keys

Important: Valet keys are NOT standard equipment on all GM vehicle lines.

Valet keys have a gray plastic head and are for restricted operation of the vehicle. Valet keys may perform the following functions:

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

Fleet Keys

Important: Fleet keys are NOT standard equipment on all GM vehicle lines.

Fleets keys allow full access to the vehicle just as a master key would. However, unlike a master key which may only learn 10 keys to a particular vehicle, an unlimited number of fleet keys may be learned to the vehicle. Fleet keys are only used in vehicles configured for fleet use with RPO 6E2 or 6E8.

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

Security Indicator

The theft deterrent module (TDM) can command the instrument panel cluster (IPC) to illuminate the security indicator only when the ignition key is in the ON position. The TDM will command the security indicator be illuminated any time a fault is noted in the immobilizer system and when the engine starting is disabled.

© 2009 General Motors Corporation. All rights reserved.

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