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2006 chevy
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38 Posts
Discussion Starter · #42 ·
I hear you.
OK. I'm reading about the theft deterrent system on this and I learned some things that clear up some of my confusion.

Basically, it has two theft deterrent systems. The CTD and VTD.

The CTD is the Content Theft Deterrent and it does not disable starting. It does utilize the front door modules as an input. It' also will turn on the Security light on the dash with the key off or in Acc.

The VTD is the Vehicle Theft Deterrent and it disables the starting. It utilizes the thingie in the keyswitch with magnets and witchcraft (!) and such. Reading the description though, it says that it will disable either the fuel or the crank system depending on engine, but it never specifies which engine uses which system and only mentions disabling the fuel system. Then it mentions that the ignition switch activates the crank relay, regardless of Passlock status.

Here are the sections on the BCM and PCM for the VTD:

Body Control Module (BCM)
The body control module (BCM) contains the logic of the Theft Deterrent System. The BCM provides the battery positive voltage to operate the Passlock™ sensor. The BCM also measures the voltage of the security sensor signal circuit. The voltage measured will indicate whether the Passlock™ sensor has been activated and whether the resistance value from the sensor is a valid value or the tamper value. If voltage measured is in the valid range, the BCM compares this voltage, voltage code, to a previously learned voltage code. If the voltage codes match, the BCM sends a class 2 message containing a password to the powertrain control module (PCM). If the voltage codes do not match, or the voltage is in the tamper range, or there is a circuit fault, the BCM will not send the correct password to the PCM, and the vehicle will not start.

Powertrain Control Module
The powertrain control module (PCM) contains the remainder of the logic of the Theft Deterrent System. If a class 2 message containing a valid password is received from the body control module (BCM), the PCM will continue to allow the fuel injectors to operate. The PCM will allow the fuel injectors to operate until it decides there is no valid password coming from the BCM. If the PCM does not receive a class 2 message, or receives a class 2 message with an incorrect password, the engine will crank and will not run or will start and stall immediately.

At the end of the BCM section, it just says that the vehicle will not start, but it doesn't say that it will or won't crank. I kinda think the assumption is that it will crank and not start, but I'm not sure. If it only disables the fuel injectors, and still allows it to start, then that system is not where the problem lies. Or lays. Whatever.

The solenoid side of the crank relay is connected to the PCM on both ends so the PCM provides both power and ground. I can imagine that the ignition switch tells the PCM to crank and it provides power to the relay, then the BCM tells the PCM to crank and the PCM provides the ground.

I'm about ready to drive the three hours, swap rigs with her and carry testing equipment with me until it doesn't start.

Have I told you that I appreciate you sticking with me on this? I do. Very much.
 

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Premium Member
'05 Chevy TB EXT
Joined
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4,051 Posts
One more point .... the relays may be in place --- and I'm not sure if we talked about this yet or not ... but they can click and still not work.

I bought a relay tester from Amazon and tested all the relays in everything I own and found there were a LOT of bad ones that were somehow still working, but were hanging by a Band-Aid.

I just this minute got back from my Amazon account - BUY IT AGAIN page and it's not there any more .. but I found another one amazingly alike the one I bought:

RELAY TESTER AMAZON LINK HERE

Light Automotive lighting Gadget Cable Red


THIS IS A GOOD AND ABSOLUTELY NECESSARY TOOL!

It cycles the relay 10 times with somewhat higher amperage than normal and if it passes, it goes GREEN.

I'm beginning to think that a LOT of our gremlin-troubles are relay related.
 

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Premium Member
2004 chevy trailblazer_lt
Joined
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2,347 Posts
Now to add another helpful tool to my need/want list!
 

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Premium Member
'05 Chevy TB EXT
Joined
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4,051 Posts
Now to add another helpful tool to my need/want list!
Yup!!! This is a good 'um that should be in every toolbox.

PS - yesterday --- in Missoula at a Dodge Truck dealer's parts store, I pulled a Snap-On truck over and bought a few tools ... one is really wild!

But the thing I wanna say is that I bought 6 deep sockets - (3x1/4" drive / 3x 3/8: drive) all 6-point and chrome and they cost me $225.00!

Then the $80.00 special tool I'll show you later .... (preview)

Font Bicycle part Twig Auto part Event



........... and a new style of high leverage ***** that I've needed to replace one I lost somehow a couple of years ago (more like 14 years ago)

Here's the old 387s that I wanted ....

Bicycle part Wood Natural material Tool Metal



...... but I had to settle upon these as a replacement nowadays! <sigh>


Pliers Wire stripper Nipper Snips Bicycle part

.
 

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Premium Member
2004 chevy trailblazer_lt
Joined
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2,347 Posts
Glad to hear you are a happy man!
 

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Premium Member
'05 Chevy TB EXT
Joined
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4,051 Posts
OK ---- let's see if anyone knows what the flat-red handled tool in the center-bottom ---- with the "U-shaped" slot and it's bent in a crazy angle --- is --- anyone know?

<I do!>

Hand tool Tool Scissors Wood Snips
 

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Premium Member
2004 chevy trailblazer_lt
Joined
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2,347 Posts
Auto trim removal tool or a windshield wiper arm removal tool.
 

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Premium Member
2004 chevy trailblazer_lt
Joined
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2,347 Posts
Rats.
 

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Premium Member
2004 chevy trailblazer_lt
Joined
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2,347 Posts
Tool to remove the pictured item from the axle in a CV half shaft?
 

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Premium Member
2004 chevy trailblazer_lt
Joined
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2,347 Posts
A tool to remove the ring from round shaft used in a power steering pump, an automatic transmission, a turbocharger, ...
 

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Premium Member
'05 Chevy TB EXT
Joined
·
4,051 Posts
A tool to remove the ring YES

from round shaft used in a power steering pump, NO

an automatic transmission, NO

a turbocharger, ... Not even warm
 

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Premium Member
2004 chevy trailblazer_lt
Joined
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2,347 Posts
Yes to the image - I did not see it before. I'm drawing a blank. I know I've removed them before, and if I recall correctly it was on an old Scott's fertilizer drop spreader.
 
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