Tech 2: No communication message

[Alberta Tahoe]

I'm looking for the short answer to the "no communication" message I get when working with the Tech 2 and my 06 Tahoe.
Some research shows that several modules have to be tested (via a multi-meter).
Anyone experience this and care to share a shortcut to a solution?
Thanks in advance.

 

[Doubeleive]

depends, for starters if your drivers side cigarette power socket does not have power then the fuse is blown and this same fuse controls communication with the obd port, so if you have power to the drivers side socket and other scanners will communicate then back to the tech2 and be sure you have the correct vin character selected, I found in a note in part of the online manual that my 03 Silverado used a different vin character than my 2012 Yukon, I think it can also depend on what part you are trying to diagnose and how you start the procedure with either the key on or key off.

 

[Rocket Man]

Agreed; check the OBD port by trying another scanner to see if it can communicate with your vehicle before troubleshooting the Tech 2.

 

[Alberta Tahoe]

Thanks for the replies.
Before finding the blown fuse, the T2 wouldn't come on at all (as you might expect). With the fuse intact, I can access the full range of menus however when trying to retrieve the DTC's, I'm greeted with the "no communication" message as posted above.
Pretty sure I have the VIN right.
Seems to me that my Innova code reader was fully functional on this 06 but my memory of it is unclear. I'll check that again and report back. Similarly, I'll check the Tech 2 up against the currently running 03.

 

[Alberta Tahoe]

Definitely vehicle related. The Innova code reader and the Tech 2 are unable to establish communication (despite being powered up by the ALDL) in the 06 while both work as expected in the 03.
I'm certain some of this issue relates to the ignition switch and it's on again, off again operation. The electrical issues have become more profound since the switch was replaced. Having sat now for a year hasn't made things any better. It's to the point where it's difficult to know where to begin (again).

 

[Rocket Man]

Definitely vehicle related. The Innova code reader and the Tech 2 are unable to establish communication (despite being powered up by the ALDL) in the 06 while both work as expected in the 03.
I'm certain some of this issue relates to the ignition switch and it's on again, off again operation. The electrical issues have become more profound since the switch was replaced. Having sat now for a year hasn't made things any better. It's to the point where it's difficult to know where to begin (again).

Damn that's not good. But at least you know you don't have to fix the Tech 2.

 

[swathdiver]

I do not think you need the Candi module for your 2006. You can either remove it or set to bypass in the main menu of the Tech2. May or may not do anything since the other tool is having mirrored problems with it too.

Hey Mark, your sig photo, isn't the Silvy a reverse image? The shark fin is on the passenger side.

 

[Rocket Man]

I do not think you need the Candi module for your 2006. You can either remove it or set to bypass in the main menu of the Tech2. May or may not do anything since the other tool is having mirrored problems with it too.

Hey Mark, your sig photo, isn't the Silvy a reverse image? The shark fin is on the passenger side.

I never noticed. Maybe @Sevenevez had something to do with that since he made that sig without me even asking!

 

[Doubeleive]

sometimes it can also depend on what you are trying to access or test with the tech2. what are you trying to get codes from? some stuff is in unexpected places, and aside from a vin character I think in some places it has a list of alphabetical letters as a secondary choice? I haven't played around with mine too much but it seems to be a trial and error thing without reading a full manual on the darn thing

 

[Rocket Man]

sometimes it can also depend on what you are trying to access or test with the tech2. what are you trying to get codes from? some stuff is in unexpected places, and aside from a vin character I think in some places it has a list of alphabetical letters as a secondary choice? I haven't played around with mine too much but it seems to be a trial and error thing without reading a full manual on the darn thing

Also if you don’t have a particular module you’re trying to access. On the menu for my vehicles there’s some modules listed that I don’t have, like a suspension control module on my Silverado that it doesn’t have because that was an option. If I try to access it, I get that same “no communication “ message.

 

[Alberta Tahoe]

It doesn't make a difference what or how I'm trying to access information. Something as simple as retrieving any stored DTC's gets the no comms message. Same applies for selecting the PCM, BCM or whatever other modules I have. No comms.

 

[swathdiver]

Can you take some photos of the Tech2's screen while hooked up to the truck for us Kevin?

 

[Alberta Tahoe]

Already thought about doing that.
Stay tuned...

 

[Alberta Tahoe]

An update for those that may be interested.
I went with my code reader first as I've had the most luck with it.
Here's the scoop:
After letting the disconnected battery charge for a few days, reconnecting gives full functionality to the dash. Gauges sweep as normal, etc. No start or crank as before.
All gauges come on as normal then shut down after 30 seconds.
In the meantime the dash display shows:
Check tire pressure
Reduced engine power
Service stability
Service 4wd
Also in that 30 second window my scan tool picked up DTC U0107. Lost Communication with Throttle Actuator Control (TAC) Module
Then comms via the scan tool are lost. Everything just shuts off on it's own.
Gauges stop working as normal (e.g. fuel gauge shows empty rather than the 1/2 tank that's there).
The ignition key has no function: Remove key, idiot lights stay on. Daytime lights stay on. Disconnecting battery resets lights however gauges are still inoperative.
Battery voltage drops from 13.4 to 12.7 in 30 seconds.
That where I'm at at the moment.

 

[Doubeleive]

I would check your harness to the BCM, look for any corrosion

 

[Rocket Man]

So you have more problems than first mentioned. An electrical drain like you describe can be hard to locate. Besides the BCM harness, I’d check the positive battery cable as well as all grounds. It sounds to me like you don’t have enough voltage to power up pretty much anything. I’d also first try a different battery, it could be as simple as that.

 

[Alberta Tahoe]

I've listed all of the problems that have cropped up but they're spread out across several threads in an attempt to get to the bottom of this.
It all started with an intermittent electrical dropout when travelling over rough roads or hitting a pot hole at cruising speeds.
From there it's led to a no start/no crank condition.
Etc, etc.
Undoubtedly the connections are suspect. That it's been sitting for a year outdoors (in this part of the world) hasn't helped any.
As for the battery, I've used several. All with the same results.
I had mentioned before that I've replaced the electrical portion of the ignition switch. That calls for a key re-learn however, the dash functionality, or lack of it, is preventing the use of the re-learn procedure. That is to say, the security light doesn't stay on as is the requirement and any attempt at the re-learn has no effect.
It's a safe bet that the original problem is corrosion related and is still there. But it's been compounded by additional issues not the least of which is my unnecessarily replacing the ignition switch. That has most certainly made matters worse.

 

[swathdiver]

An update for those that may be interested.
I went with my code reader first as I've had the most luck with it.
Here's the scoop:

Have you used the Tech2 with an external power source different from the truck's OBDII or cigar lighter?

Our 2004 Montana has communication issues as well. Can't see everything with the Tech2. Since it runs and drives just left it alone.

 

[Alberta Tahoe]

Interesting you should ask.
When first connected and the cigar lighter fuse blown, I had to use the external 12VDC power supply to get things up and running. I managed to see a DTC list (or similar connection to a menu) however after about a 30 second interval, all comms stopped. Typical of the way the dash functions. All gauges sweep as they should when a fresh battery has been installed (or charged) but it all drops out after a bit. That's also how the code reader performed. It could establish comms with the various components (PCM/BCM/et al) but after a bit, comms dropped.
Points to some connection somewhere creating a drain or a back feed due to a bad connection, connectors, etc.
I deal with this kind of thing every day as an industrial automation electrician. Hundreds of connection points and various hardware and software to deal with. It pains me to have this machine get the better of me. That said, I know that taking it apart, literally, and putting it back together will solve the problem. But no thanks.
I'm still looking for the short answer.

 

[swathdiver]

Interesting you should ask.
When first connected and the cigar lighter fuse blown, I had to use the external 12VDC power supply to get things up and running. I managed to see a DTC list (or similar connection to a menu) however after about a 30 second interval, all comms stopped. Typical of the way the dash functions. All gauges sweep as they should when a fresh battery has been installed (or charged) but it all drops out after a bit. That's also how the code reader performed. It could establish comms with the various components (PCM/BCM/et al) but after a bit, comms dropped.
Points to some connection somewhere creating a drain or a back feed due to a bad connection, connectors, etc.
I deal with this kind of thing every day as an industrial automation electrician. Hundreds of connection points and various hardware and software to deal with. It pains me to have this machine get the better of me. That said, I know that taking it apart, literally, and putting it back together will solve the problem. But no thanks.
I'm still looking for the short answer.

How about a shiny new BCM? Hunting down a short inside one of those profiteth little.