GM Reverse Engineering

[VL400]

Well done Tazzi and others involved Can get some cool stuff to display now

[Tazzi]

Im noticing that the PCM (V6), doesnt exactly follow the same rules as the other modules. There is alot of data that its constantly updating though.

eg. When requesting table 2 I get:
F7,57,01,02,AF
F7 7B 01 00 00 16 3B 93 71 00 00 00 00 00 80 00 4E 00 45 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 49 49 4A 49

Unless Im picking up invalid data.. then the pcm doesnt send back showing the "Table number" as seen on all other modules.
And based off what was said earlier.. only a VY V6 PCM will actually communicate on ALDL. VY V8 and all VZ's should be obd2. Havent actually checked VZ in the tech2 yet but Id assume I wont pick up anything from the pcm.

Also.. Table 0... damn.. theres alot of data there
Think theres 106 bytes of data. May take a while to work out that one.

Also saw the tech2 firing off some F5,57,01,00,chsm.. Absolutely no clue what module F5 is.

[charlay86]

I don't think it does send the table number back, only the ID, length and mode.
VT V6 PCM is F5
VY supercharged V6 could be the same?

[VL400]

Correct, F5 is for all MAF PCMs except the flash PCMs that use F7. So, yeah S/C PCMs are F5.

The mode 1 message 0 table is well defined in the the logging ADX so pretty much every byte function can be found there. Will also log the trans in another message, also in the same ADX.

[Tazzi]

Correct, F5 is for all MAF PCMs except the flash PCMs that use F7. So, yeah S/C PCMs are F5.

The mode 1 message 0 table is well defined in the the logging ADX so pretty much every byte function can be found there. Will also log the trans in another message, also in the same ADX.

Ah really? Interesting.. Tech2 only sent off the F5 message after it displayed the "no communication" message when it didnt get a response from the F7 frame.

I didnt know the ADX tables requested pcm table data. Well, Iv never logged while tunerpro has been going, I figured it was picking all the info up from the "41" id frames.. since that looked like it contained the engine information. Didn't actually know it sent off pcm request frames
Yeah I saw when I clicked on Trans, it also grabbed table 0 and another table.

Can clearly see cars vin, partnumber and identifier in one of the tables.. no clue what the rest of the bytes are in there.. guessing they would be software version, vap ect as seen in other modules

[antus]

The pcm data ones are more like messages. The ecu/pcm constructs the message when its asked for it with what data GM chose to put in there. Internally its not arranged in the same order its spat out.

[Tazzi]

Would have though it would have been more methodical to follow what they did for all other modules.
Even more weird when the tech2 craps it self (receives invalid data and freaks)

Anyway.. will keep plucking away at it all.

The ABS module is an interesting one, seems as soon as any information is requested from the ABS.. It pauses communication which throws the ABS error. Although "realtime" info can be pulled which doesnt set the abs error off (is an option in the tech2 to do).

[Tazzi]

Have been trying to capture the "ABS Bleed Procedure" and seem to be struggling. Originally I thought there was something wrong with my setup and something was happening to the connection and picking up/losing frames. But I tried in car today, I plugged in the tech2, got to the bleed procedure.. then as soon as I clicked enter, I pulled out the diagnostic plug (Since I dont actually want to do the bleed!) and still go the same results.

Everytime I do the bleed procedure. the tech2 fires off a whole heap of frames (quite large!).. but there not the same each time though..

Code: Select all

From Tech2: F9 D8 06 04 00 01 00 00 12 06 00 6B 01 A6 20 78 D1 01 F0 05 7A D6 21 95 02 36 A3 01 9C 20 2A A2 2B 7C A2 2B 7E A2 2B 7A 09 01 7A B1 04 28 B2 2B 20 28 1E E0 28 F8 07 40 A0 7C 78 04 7E 7C B1 30 20 AD 14 28 28 0B 99 08 29 DF 05 17 40 20 28 60 F0 A3 01 A2 20 1C A3 01 AC 20 1E A2 1D 00 80 E1 40 00 02 DF 1F 94 20 22 D7 F1 08 0A 22 64 1E 22 A2 22 22 71 07 25 11 02 08 10 10 20 A0 12 22 40 00 04 07 00 00 10

From Tech2: F9 D8 06 04 00 01 00 00 12 06 00 6B 01 A6 20 78 D1 01 F0 05 7A D6 21 95 02 36 A3 01 9C 20 2A A2 2B 7C A2 2B 7E A2 2B 7A 09 01 7A B1 04 28 B2 2B 20 28 1E E0 28 F8 07 40 A0 7C 78 04 7E 7C B1 30 20 AD 14 28 28 0B 99 08 29 DF 05 07 20 A0 00 C8 F0 A3 01 A2 20 1C A3 01 AC 20 1E A2 1D 08 02 79 A1 03 12 FA F7 44 06 09 E9 17 08 0A 22 64 1E 22 A2 22 22 71 07 25 01 00 08 02 02 00 18 20 00 02 04 10 00 00 00 00

Iv never seen a mode6 before, I was expecting a mode 4 since it would be manually controlling the valves.
Anyone ever had trouble like this before? I thought it was a dodgy connection on the bench, but in car produced the same results. And fairly certain the "checksum" isnt correct.. so the rubbish data could be even larger then what Im seeing

You can see somewhat of a pattern, although ud expect it to spit out the same frames each time the bleed procedure is performed although its slightly different everytime. Could be a software problem I guess?

[Tazzi]

Not sure if this is something that anyone would want to add to Tunerpro?
Went through the engine tests/functions available for engine (VY V6).. Will move onto the transmission tomorrow.

Code: Select all

-IAC System
       -RPM Control
  “Clicking increase!”
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C3 5E 00 00 00 00 00 00 00 00 78
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C3 62 00 00 00 00 00 00 00 00 74
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C3 64 00 00 00 00 00 00 00 00 72
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C3 66 00 00 00 00 00 00 00 00 70
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C3 68 00 00 00 00 00 00 00 00 6E
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C3 6A 00 00 00 00 00 00 00 00 6C
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C3 70 00 00 00 00 00 00 00 00 66
When Exiting: From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9

       -IAC Control
Clicking increase
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C1 64 00 00 00 00 00 00 00 00 74
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C1 7D 00 00 00 00 00 00 00 00 5B
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C1 96 00 00 00 00 00 00 00 00 42
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C1 AF 00 00 00 00 00 00 00 00 29
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C1 C8 00 00 00 00 00 00 00 00 10
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C1 E1 00 00 00 00 00 00 00 00 F7
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C1 FA 00 00 00 00 00 00 00 00 DE
When Exiting: From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9

       -IAC Reset
Click reset
From Tech2: F7 6C 04 00 00 00 00 10 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 C9
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9

       -Base Idle
Request to hold 2000rpms then click continue:
From Tech2: F7 6C 04 24 00 00 00 04 00 00 00 00 00 00 00 C5 00 8C 00 00 00 00 00 00 00 20

then Requests to adjust TPS back to desired idle
When exiting: From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9

-EGR Control 
Click increase
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 80 00 00 00 13 00 00 00 00 00 06
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 80 00 00 00 26 00 00 00 00 00 F3
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 80 00 00 00 39 00 00 00 00 00 E0
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 80 00 00 00 4C 00 00 00 00 00 CD
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 80 00 00 00 5F 00 00 00 00 00 BA
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 80 00 00 00 72 00 00 00 00 00 A7
When Exiting: From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9
 
-Reset Cells
From Tech2: F7 6C 04 00 00 00 00 08 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D1
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9

-Bypass Spark
Spark mode is on Bypass…
Clicking EST
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9

Clicking Bypass
From Tech2: F7 6C 04 00 00 00 00 04 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D5


-Air Fuel Ratio
Currently on 14.7 : 1
Clicking increase:
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C4 00 98 00 00 00 00 00 00 00 3D
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C4 00 9D 00 00 00 00 00 00 00 38
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C4 00 A2 00 00 00 00 00 00 00 33
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C4 00 A7 00 00 00 00 00 00 00 2E
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C4 00 AC 00 00 00 00 00 00 00 29
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C4 00 B1 00 00 00 00 00 00 00 24
When Exiting: From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9


-Output Tests
     -Fuel Pump
Turn On: From Tech2: F7 6C 04 40 40 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 59
Turn Off: From Tech2: F7 6C 04 40 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 99
Exiting: From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9

     -A/C Clutch
Turn On: From Tech2: F7 6C 04 20 20 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 99
Turn Off: From Tech2: F7 6C 04 20 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 B9
Exiting: From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9

     -Check powertrain Lamp
Turn On: From Tech2: F7 6C 04 10 10 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 B9
Turn Off: From Tech2: F7 6C 04 10 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 C9
Exiting: From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9

     -High Fan
Turn On: From Tech2: F7 6C 04 04 04 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D1
Turn Off: From Tech2: F7 6C 04 04 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D5
Exiting: From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9

  
   -Canister Purge
Turn On: From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 08 FF 00 00 C0 00 00 00 00 00 00 00 00 00 D2
Turn Off: From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 08 00 00 00 C0 00 00 00 00 00 00 00 00 00 D1
Exiting: From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9

     -Starter Relay
Turn On: From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 02 00 D7
Turn Off: From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 02 02 D5
Exiting: From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9


Clicking On Function Tests
-IAC Circuit
Informs user engine must be hot! Cant be cold! (roughly 80degs)
“IAC Will Be Cycled Automatically. Do Not Move the Throttle!”
From Tech2: F7 6C 04 04 04 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D1
From Tech2: F7 6C 04 04 04 00 00 00 00 00 00 00 00 00 00 C1 D5 00 00 00 00 00 00 00 00 FB
From Tech2: F7 6C 04 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D9

-02 Sensor (Need closed loop to perform this.. will come back)

-Power Balance
“Injectors will be turned off Sequentially”
(Does a whole heap of frames turning each injector on and off and checks change in rpm)

-Low Fan
Turn Low speed fan request:
On: From Tech2: F7 6C 04 08 08 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 C9
Off: From Tech2: F7 6C 04 08 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D1
Exiting: From Tech2: F7 6C 04 08 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00 D1

[Holden202T]

that's some good info there!