I just heard of this app can that supposedly scan all GM systems. I just downloaded it but haven't tried it yet. The Lite version is free however hasn't been updated since 2017 and reviews are mixed. The Pro version for $3.79 has been recently updated but not too many downloads nor reviews but seems promising.
Definitely something to look at if you need the scan more than just Powertrain codes.
I just heard of this app can that supposedly scan all GM systems. I just downloaded it but haven't tried it yet. The Lite version is free however hasn't been updated since 2017 and reviews are mixed. The Pro version for $3.79 has been recently updated but not too many downloads nor reviews but seems promising.
Definitely something to look at if you need the scan more than just Powertrain codes.
So yesterday I explored a little with this Chevrosys. It did indeed scan the EBCM and the SIRS systems as well as the PCM. It has no capabilities for the TCCM, BCM, DDM, PDM, LGM, HVAC, Radio, Amplifier, IPC, etc.
Behind the scenes it uses precisely the same message structures that @blurry posted on the forum some ten years ago. So in short it doesn't do anything you cannot do yourself following @Blurrys post.
Last year I spent a lot of time trying to pull TCCM codes from an 02 trailblazer. At the end I was able to access them manually via the command line. Below is the writeup on it. Hopefully this helps some folks diagnose their own 4WD issues :) There is a lot of info below, if you are looking...
gmtnation.com
That is too bad that it is limited to just those few systems. Would have been good for us mere mortals who are hyperterminal illiterate
Ahh, I was wondering if newer versions of Android had killed it. I am on Android 11 and it still works here.
I have one issue most folks don't when it comes to connecting to a Bluetooth OBDII adapter. I have something like 6 of these things and they ALL use the very same Bluetooth name. So when I try to connect to a specific device it leads to a guessing game when the app does not display the MAC address of the adapter. At times I have to delete/unpair several OBDII adapters and start over.
Last year I spent a lot of time trying to pull TCCM codes from an 02 trailblazer. At the end I was able to access them manually via the command line. Below is the writeup on it. Hopefully this helps some folks diagnose their own 4WD issues :) There is a lot of info below, if you are looking...
gmtnation.com
That is too bad that it is limited to just those few systems. Would have been good for us mere mortals who are hyperterminal illiterate
I am going to reread the whole thing. I think I may have erred in trying to explain the whole shebang in verbose detail. I am thinking maybe a brief example that deals specifically with retrieving the current significant codes from a single module, like the EBCM or the TCCM.
Man, if you could write an app that could do all this in the background and display results you could make some serious coin, even at $0.99. A nice app similar to Chevrosys that can scan all systems. However that would require a lot of development and access to multiple vehicles and years to test.
Who cares about the other vehicles? Just make it work for the GMT360/370
I'm running android 5 and Car Gauge Pro works fine. I get the EBCM and TCCM codes so it's OK.
I've had Car Gauge Pro for a while and it's was flaky at times. Sometimes it would work, other times not. I haven't touched it in a long time since I have a Tech 2 but still use Torque Pro once in a while just for a quick code check and to monitor parameters.
Made a lil progress with CGP. The generic connection doesn't work for me, but the GM one did (sort of) My OnStar report keeps telling me there's an ABS problem, but I have no lights. CGP scanned a bunch of stuff, but reported nothing from the ABS system.
Installed Chevrosys, and ran a scan, it came back with C0055 for the rear wheel speed sensor. Guess I can look into that this weekend
Seeing that (Blckshdw's) post, I downloaded the Lite version just now, and will try it out.
For US peeps... the Pro version is listed @ $2.99 on Google Play.
So a little behind the scenes info here.... If in CGP you opt to use the "App default" level of scan.... For the PCM CGP requests Current, Pending, MIL Requested, and one of the two MFG levels (0xCA for those who have read Blurrys post). But for all the other modules CGP only requests "Current" level code status (0x02). If you are interested in History, Pending, or Old codes for these other modules you need to explicitly ask for them instead of using "app default".
Seeing that it's historical, I wouldn't even bother with it except clear it. It's probably just another way for OnStar to get you into the stealership for a scan.
CGP did return a handful of codes on my morning commute, and after looking them up, they appear to be historical too although they app does list them as current, so now I really dunno what the deal is with this app. But yeah, I know the Onstar people just want to get me in some pipeline to get the dealership some $$$
The battery DID get run down pretty far a few times before we returned to the office, since there were periods where I didn't leave the house for weeks at a time. Had to put the trickle charger on it here and there.
The Battery Rundown Protection function allows the Body Control Module (BCM) to disable courtesy lights, cargo lights and underhood light 40 minutes after the ignition is turned off. The BCM monitors the output of the inadvertent power relay. When BCM commands the Inadvertent Power Relay on and there is no voltage at BCM connector 0.5 seconds, Diagnostic Trouble Code (DTC) will be set. DTC will not set if system voltage is not 9-16 volts. When DTC is set, courtesy lights, cargo lights, and underhood light will be disabled.
I had to replace one of my HID bulbs back in the summer, and did disconnect a few things for testing. Wouldn't think doing that, would cause this though. Can't recall if I did any relay swapping for testing other stuff in the front fuse block.
When the Body Control Module (BCM) senses a request for low beam headlamp illumination, the BCM sends a ground signal to the low beam headlamp relay through the headlamp low beam relay control circuit. The headlamp low beam relay will apply voltage to illuminate the headlamps. The Diagnostic Trouble Code (DTC) sets when the BCM receives a command to illuminate the low beam headlamps and the headlamp low beam relay control circuit is open or shorted to voltage or when the BCM does not receive a command to illuminate the low beam headlamps and the headlamp low beam relay control circuit is shorted to ground.
Light research on this suggests faulty ignition switch, which is something I was dealing with when my HVAC blower was only working intermittently a few months back.
The Body Control Module (BCM) monitors the ignition key alarm switch. When the key is in the ignition, the ignition key alarm switch is closed with the signal circuit as low. When the key is not in the ignition, the ignition key alarm switch is open with the signal circuit as high.
It's OnStar, when I've needed to use it, it worked, so meh...
The OnStar® button assembly consists of 3 buttons: Call/Answer, OnStar® Call Center, and OnStar® Emergency. The Telematics Communication Interface Control Module supplies the OnStar® button assembly with 10 V via the 10 V reference circuit. Each of the buttons, when pressed, completes the circuit across a resistor or set of resistors allowing a specific voltage to be returned to the Telematics Communication Interface Control Module over the signal circuit. Depending upon the voltage range returned, the Telematics Communication Interface Control Module is able to identify which button has been pressed.
Chevrosys didn't give me any of these, although I don't see an option for Body related codes. At least not in the free version.
I get a little fuzzy when thinking of "History" vs "Old" vs "Stored" codes. In the SAE J2190 specification there is no mention of "history" as a status level.
This grab from a page at FastFieros, attributed somewhat to " Paul from EFI Live" is where I first saw a reference to "history" codes.
That post looks to say the a history code is one that has freeze frame data??
From my own reading of codes across a handful of modules it seems that the bit 5 codes, "warning lamp was previously illuminated..." Are the ones that hang around the longest.
That's not the app. A given code can have many levels of code status set. CGP is just reporting what bits are set. A code can be current, history, and pending all at once!!
Edit: I would say the thing that is confusing is that CGP gives you access to a whole raft of information that the basic code readers strip away.
I'll try clearing those codes on the way home this evening, since everything seems to be working as expected, and see if they come back in the morning. Probably my truck's way of telling me to get an expensive fancy tool.
I think there are some code status that cannot be cleared by ANY scantool. Like those "bit 5" level codes that hang around for years.
I have seen statements in service literature that a "History" code can be cleared with a scantool. I am going to have a look and see how that is done and is it really any different than clearing any other code status. I currently think that a "History" code level equates to a bit 4 status level.
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