I recently purchased a clone GM Tech2 scanner to access the diagnostics in my 2006 Hummer H2. The scanner is operational and can scan all protocols but cannot link to any of them. There are no driveability issues. I performed troubleshooting by doing the following:

1. Verified that the Power Control Module (PCM) and Data Link Connector (DLC) fuses were okay.
2. Tested DLC pins 4 (chassis ground) and 5 (PCM ground). The voltage was less than 0.1 which led me to believe low resistance.
3. Performed a volt reference check on DLC pin 2 (serial data) to determine if it was 5 volts and actual voltage was between 1 and 2.
4. Tested DLC pins 4 and 16 (battery) and the voltage was 12.58.
5. Checked the purple, black, black/white and orange wires on the back of the DLC for integrity and did not find any issues with fraying or looseness.

I am not sure what to think, whether the issue is with the PCM or wiring. I am trying to locate a wiring diagram for the PCM and DLC which will give me a better understanding of the wire mapping. I know the PCM has two connectors and I probably should see if there is continuity in the purple wire (Pin 2) and its termination in one or the other connector.

Any recommendations? Thanks for any advice you may have.

 

Have you tried a scanner that you have verified to work?
Might be the Asian knock-off "clone" Tech2.

 

Tainter,

Thanks for your feedback. In fact, I did use another scanner and it did not communicate as well. The other scanner can access the OBD2 port on my Ford F-250.

Any ideas?

 

Not sure what year CAN Bus started, but a 2005 is definitely Class 2 i.e serial data on pin 2. Do you have the Tech2 CANDi bus module?

Assuming yours is not CAN bus, then you have already correctly identified the correct DLC pins.

Do you mean PCM (PowerTrain Control Module) or BCM (Body Control Module)? Unfortunately the wiring of the modules

So there could be several possibilities:-

• Your TECH2 is not communicating (possibility) You might need the CANDi bus module (I checked my H2 still communicates with the CANDi unit fitted and it does)
• You have an issue with your Class 2 Data bus (see Splice Pack 2005 on the attached PDF) There are many modules, all connected in parallel, an issue with any one of them could affect communications (
  see this video for location of SP205
  ) I'm sure you would have noticed something not working (so unlikely).
• The DLC pin 2 (Purple wire I think) could have become disconnected from SP205 (unlikely, depends on vehicle history)
• Are you powering the TECH2 seperately of from the DLC port? Only the DLC port is needed, theres is no need for external power (something I did wrong in the early stages of testing)

You may find the "Network Comms & Diagnosis" pdf useful and a good reference (see page 35)

Please keep us updated with your progress, good luck!

 

are there any fetures that are not functioning? it could be a bad module on the can bus. there is a connector under around the DLC connector body control module area that terminates all the bus lines. maybe check it. you might have to pull pin by pin to isolate the issue.
https://www.techconnectcanada.com/bl...d-lan-concerns this one states 2008-9 hummer but most should still pertain to older models

 

Check that your "cig lighter" fuse ion the under hood fuse block is not blown. That provides power to the DLC connector.

 

oceanbrave, bronxteck and MixManSC,

Thanks for your input. I previously watched the YouTube video on the SP205 and the cigarette lighter fuse was checked as part of my troubleshooting.

I’ll need to go back under the dash and troubleshoot further. Hopefully, I’ll find the culprit.

 

Apologies the PDFs I posted didn't get uploaded??

Your TECH2 has power and you've confirmed DLC has 12.58V taking these details from your opening post.

 

Here too is the "Network Comms & Diagnosis" pdf Page 35 describes how you can check there is comms activity.

Seems only one pdf at a time

 

Seems limit is 5MB, again see P35 might (if Serial 2 Data not CAN, save removing the dash)