VCM Scanner or GM MDI2 + Tech2Win

[ChemEng201612]

Does the VCM Scanner have the same control/advanced diagnostic capabilities as a GM MDI2 + Tech2win? Tuning is something I want to get into later, but my main need at this time is diagnostics. If I'm spending $800+, I would rather buy HPTuners than the GM MDI2+ as long as they do the same thing for diagnostic/repair need. I read through this thread GM Scan Tool Functionalities (hptuners.com) and it seems like VCM Scanner is not as capable as GM MDI2 + Tech2win, however that was now 4 years ago and has VCM Scanner improved?

Here is my problem:
I have a 2018 GMC Sierra 2500 Duramax L5P. We had a freeze in Iowa this past January dropping temps to -17 DegF. The DEF line heater #1 (or A) failed and a permanent DTC code P248A came up along with P20B9 and P20BB. The Truck immediately got the "Service Emission System Now". The Freezing weather is gone, I cleared the DTC's, no check engine light exists anymore but the permanents stayed on and the truck is in Limp mode. I believe right now I am 4 miles away from max of 55 mph which equates to Level 3 of 7 in the emission control strategy.

I am not looking to bypass, delete, or modify the emission system. The diagnostics that I need to do after fixing my part is to be able to "Command a second Reductant System Tamper Warning Service Bay Test On with a scan tool" per the GM Procedure for clearing Permanent DTC Emission codes. The procedure from GM that I will be following is below:

Reductant System Tamper Warning Service Bay Test
Note:
If the reductant level warning status is at level 4 or higher, fill the DEF tank and perform the Reductant Fluid Tank Level Reset procedure.
The scan tool must remain connected to the data link connector(DLC) during the entire Reductant System Tamper Warning Service Bay Test.
Do not perform the Reductant System Tamper Warning Service Bay Test if the diesel exhaust fluid (DEF) temperature is less than −7°C(19°F).
If the Reductant System Tamper Warning Service Bay Test is inhibited for any reason, a second Reductant System Tamper Warning Service Bay Test will need to be performed.

• Verify DEF tank is full and not in reductant warning level restriction.
• If the reductant system is in restriction
• Fill the DEF tank and perform the scan tool Reductant Fluid Tank Level Reset procedure.
• If the reductant system is not in restriction
• Perform the Ambient Air Temperature Reset with a scan tool if the vehicle has been driven in an outside temperature below −5°C (+23°F).
• Engine idling and at operating temperature, observe the DTC information with a scan tool. Verify there are no DTCs set.
• If a DTC is set
• Refer to Diagnostic Trouble Code (DTC) List - Vehicle
• If a DTC is not set
• Disconnect scan tool.
• Ignition Off for 2 minutes.

Note: Do not apply accelerator pedal after starting engine, otherwise the test will fail and will need to return to step 1 of the test. Ignition on.
Connect the scan tool and select the scan tool Reductant System Tamper Warning Service Bay Test in the K20 Engine Control Module Control Functions menu and follow the instructions.


Note: If the Reductant System Tamper Warning Service Bay Test reaches its time limit without reporting passed or failed and the Service Emission System or the Service Exhaust System message is still displayed, a second Reductant System Tamper Warning Service Bay Test will be necessary Command the Reductant System Tamper Warning Service Bay Test On with a scan tool. The Reductant System Tamper Warning Service Bay Test should start and run for up to 20 minutes.

• The Reductant System Tamper Warning Service Bay Test is complete when the Service Emission System message or Service Exhaust System message turns Off.
• If the DIC message does not clear
• Command a second Reductant System Tamper Warning Service Bay Test On with a scan tool.
• If the DIC message does not clear after the second test, a condition with the system still exists.
• If the DIC message clears
• All OK.

[blindsquirrel]

VCM Scanner can sometimes be used for diagnostics/repairs, but mostly only by accident. It is built specifically for gathering data needed for tuning. Just like how other diagnostic scan tools might accidentally be able to gather data useful for tuning.

There is no one tool that will do everything.

[ChemEng201612]

There is no one tool that will do everything.

Thanks for the reply, it's unfortunate there isn't one tool that can do it all. For now then, I'll get the GM MDI2 + Tech2win for base level diagnosing issues before getting a tuner. Can't tune if your truck aint working first, afterall.

[gtstorey]

The diagnostic tools will allow for accessing modules that HPT hasn't even thought about touching since they don't have any relation to tuning.

[ChemEng201612]

I?ve placed my order for the GM Diagnostics route. Going to try the VXDIAG VCM Nano as a knock-off try first. If that doesn?t work, then I get the Bosch GM original MDI2.

[gtstorey]

I’ve got the vxdiag and seems to work ok, but never tried it on newer stuff. The only thing I’ve found that is missing is the instrument cluster test.

You also might look at some of the all vehicle scanners such as Autel or TopDon.