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Steve, ASE L1 Master Technician
Category: GM
Satisfied Customers: 5494
Experience:  25+ Years experience as a professional working automotive technician; ASE L1 master technician
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2006 GMC canyon has a starting problem runs excellent but every

Resolved Question:

2006 GMC canyon has a starting problem runs excellent but every so often it wont start you can crank and crank on it and it wont start if you walk away for 10-15 minutes try it again and it will fire right up. the fuel pump is working and it has adequate fuel pressure any help would be appreciated
Submitted: 7 years ago.
Category: GM
Expert:  Steve replied 7 years ago.
When it does not start, is the security light flashing on the instrument panel?
Customer: replied 7 years ago.
Expert:  Steve replied 7 years ago.
To narrow down the possible causes for the problem you will need to do a little diagnopstic testing when the no-start problem is occurring.
To start, connecting a code reader tool or a scan tool to the truck's data connector to see if there are any fault codes stored in computer memory will be helpful. If you do not have a code reader tool, many auto parts stores will do this for free for you.
Security system problems causing this condition are very common on this vehicle, but the security light would be on if it was security system related, so if the light is not on that pretty much rules out the common things.
When it is not starting, we will need to know if it is losing spark, fuel injector ground pulse, or both. You can purchase an inexpensive spark tester tool at any auto parts store for a couple of dollars. To check the injector signal, you will need a tool called a noid light; this is plugged onto an injector electrical plug and will flash when cranking the engine if power and ground pulse are present at the injector.
If you can test these three things and let me know what you find, it will give us a place to begin diagnostic testing to find the cause of the problem...
Customer: replied 7 years ago.
Hi there I think that it is loosing spark but I will definatley check that to be sure I am sure it will do it again within thenext day or two. if it is loosing spark where do I go from there?
Expert:  Steve replied 7 years ago.
It is important to know if it is losing spark or losing both spark and injector pulse at the same time; diagnostic testing can end up going in different directions depending on what exact test results you get from the 3 checks I mentioned. losing spark only is going to lead in the direction if testing ignition system components and circuits. losing spark and pulse together is going to go more in the direction of testing engine control system components and circuits.
Customer: replied 7 years ago.
Thanks, XXXXX XXXXX follow your direction to a T I am pretty mechanically inclined cut when it comes to problems on a vehicle this new there is alot of electronics I am not that familar with this truck has been took to 3 different dealers and when they have it they can find nothing wrong I am sure that you can understand problems like that but please stick with me and I will make this well worth your while. Thanks, Brian
Customer: replied 7 years ago.
Hi there after thinking about this further the security light is on assuming it is a litup padlock sometimes it stays on and sometimes it flashes and goes away sorry it never really dawned on me that was the security light. where do we go from there?
Expert:  Steve replied 7 years ago.

That does narrow down the source of the problem quite a bit then...

Your Canyon has a factory security system called Passlock. It basically works like this:

Located inside the ignition lock assembly is a signal generator. When you turn the correct key in the ignition, this generates a signal that is sent out over the truck's class 2 data network. The body control module receives this signal and compares it to one that was stored in memory when the system was first programmed; if they match the BCM then sends a second "start enable" signal over the data network that is received by the powertrain controller. If the PCM receives this signal it allows the engine to start; if anything at all goes wrong in this sequence of events the PCM disables fuel injector oepration for 10 minutes. If three unsuccessful tries are made to start the truck, the PCM then disables starting for 30 minutes untill another successful attempt can be made.

The most common failure in this system producing intermittent no-start problems is a failing passlock sensor (part of the ignition lock cylinder assembly). However, a poor electrical connectiona t any point, an internal body control module fault, or RF interference from aftermarket electrical accessories can all cause problems with the passlock system.

This system does have the ability of generating diagnostic fault codes and displaying some live data to aid in diagnosing the cause of problems. However, the only scan equipment with the capability of accessing the security system data on GM vehicles is the Vetroniz Tech-2. For that reason, you will likely need to take the truck in to a GM dealer service department or to an independent shop with a tech-2 to be diagnosed; theree really is no accurate way to diagnose faults in this system without the factory scan tool...

The good news is that most GM dealer parts departments stock the common failure components (hall effect sensor, wire connector repair terminals, BCM) because faults with Passlock systems are a very common problem on several GM vehicle lines.

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