E38 HS canbus messages

Bosch Motronic etc ECUs and PCMs
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E38 HS canbus messages

Postby snap » Fri Nov 06, 2020 8:02 pm

Does anyone have any canbus data they can share? Especially keen for VE commodore?

I am currently doing an L77 VE Holden Commodore engine conversion (without BCM) into a holden rodeo and I am trying to learn what all the messages are. The GMLAN bible doesn't really cover the 11 bit HS can much so I am learning it all the hard way.

I figured out I can use the Ox1F5 message to trigger the reverse lights. 1F5 contains the PRNDL shifter status from the 6l80e. RPM seems to be in the 0C9 message

However, I am pretty keen to hunt down the AC compressor request message that would normally go from the BCM to E38 ECM. Anyone have ideas? I am happy to trawl through the data if anyone is willing to share.

Thanks

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Re: E38 HS canbus messages

Postby ironduke » Sat Nov 07, 2020 3:04 am

I had been looking into that, but lost the need and lost interest..

1A1 looks promising.. I think it's more A/c clutch applied/A/c clutch not applied, not the request your looking for..

Looking a little deeper, on the 08 suburban I logged the low pressure cycling switch goes to the hvac module, so this might be it?
you see 1A1002000 when the a/c clutch is engaged
1A1000000 shows up the second it dis engages.. keeps outputting this message if you turn the ac off, or until the clutch engages again..
Seems to match the ac request signal with tech2win exactly..
Every now and then I see 1A1001000, but not very long and not sure if clutch is engaged or not when this happens..
Tried sending this message on my bench E38 but it currently has a 2013 OS so I doubt it's the same message, plus there's no RPM reading and a ton of codes so unless it worked I can't say it'd fail.. lol
Tried spoofing it on the bus of the suburban but it didn't change anything.. I'd have to kill the BCM to stop the other messages so this isn't a good test either..


What year are you trying for?



Here's a log of a suburban.. Turned t he A/C on/off about 10 times in the log..

Trying.ac.request.alldata.log.txt
(1.35 MiB) Downloaded 8 times

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Re: E38 HS canbus messages

Postby ironduke » Sat Nov 07, 2020 5:19 am

Well..


1F1AE1600000800007A << this turns the ac clutch on in the suburban..
1F1AE0E00000800007A << this seems to turn it off.. or if it stops seeing the message above after a couple seconds..


This works on my bench E38 flashed to the 08 suburban file.. Without an RPM reading.. Ac request changes from yes to no...

So good chance this will work on a stand alone E38 without a BCM to control the ac... woohoo!!! Don't remember why I stopped digging into this..

If you don't mind, post up your bin or OS if the messages I posted don't work, might be able to set something up if the message is different for a different OS?

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Re: E38 HS canbus messages

Postby snap » Tue Nov 10, 2020 8:02 am

Thanks for for sharing the suburban log. Very helpful! In fact, on initial glance it does look very similar to my log but I need to do some more digging.

ironduke wrote:What year are you trying for?

Targeting the 2011 E38 for the L77 6.0 - OS 12639270

ironduke wrote:1F1AE1600000800007A << this turns the ac clutch on in the suburban..
1F1AE0E00000800007A << this seems to turn it off.. or if it stops seeing the message above after a couple seconds.


I suspect these are the "device control" messages for diagnostic tools to test devices on the can bus are working. My understanding is that this is not the normal request for operation and that the "tester present" message must be sent for the activated device to stay enabled.

You are right: there are a number of conditions that are required for the AC to be permitted by the ECM to start so difficult to simulate on the bench:
    -A/C Pressure is between 196 kPa (28 psi) and 3250 kPa (470 psi).
    -Engine coolant temperature (ECT) is less than 119°C (250°F)..
    -Engine RPM is more than 400 RPM.
    -The A/C request signal is set to engage.


Ill keep investigating this and report back my findings. Ill also dig up the info from the manual as it vaguely explains how the HVAC/BCM/ECM interact.

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Re: E38 HS canbus messages

Postby antus » Tue Nov 10, 2020 9:23 am

You guys may be aware, but if you are not the GMLAN bible here covers a lot of IDs. I am not sure if it covers what you are looking for. https://docs.google.com/spreadsheets/d/ ... edit#gid=1
Have you read the FAQ? For lots of information and links to significant threads see here: viewtopic.php?f=7&t=1396

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Re: E38 HS canbus messages

Postby ironduke » Tue Nov 10, 2020 10:33 am

antus wrote:You guys may be aware, but if you are not the GMLAN bible here covers a lot of IDs. I am not sure if it covers what you are looking for. https://docs.google.com/spreadsheets/d/ ... edit#gid=1


I'll have to have another look at that, but last I knew it the gmlan bible was for single wire low speed lan, not sure how much would cross over to high speed can??

For the OP..

This message changes the a/c request from yes to no when sending it on a bench ECU.. This is not engaging the clutch and this is not from sniffing output tests using a tech 2, so hopefully this is the a/c request signal that is sent from the BCM.. If you use a scan tool and use output tests the a/c request never says yes, it just turns on the relay.. this is not a function test command..

I just tried it on a bench E92 and that worked too, I even found a bin with your OS and tried it and it does indeed change request from no to yes!!
If your trying to set something up stand alone I do think this command would work..

BUT my bench E38 with a 2013 bin file(12653674) doesn't seem to work with this message, I even went and logged a 2013 truck and I see the same message turning the ac off and on but if I send the message myself it doesn't work on the bench or in the truck.. hmmm..

In any case I do think this could work for turning on the ac in a swap without a BCM, in the systems I have access to for schematics the low pressure or evap temp sensor goes into the hvac control and if everything is ok the request is sent to the ECM, the ECM does have a 3 wire high pressure sensor plumbed into the high side line at the compressor.. You'd have to copy that or whatever your E38 is supposed to have.. Tried the vin from the bin I fould but SI says it's invalid vin, lol.. Do they have the L77 in the USA in anything??

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Re: E38 HS canbus messages

Postby snap » Wed Nov 11, 2020 10:08 am

I initially thought you were referencing the device control messages (the 0xAE in the 1F1 messages through me off track):
    -7E0 07AE203000000000 AC clutch on
    -7E0 07AE200000000000 AC clutch (standard)
    -7E0 07AE202000000000 AC clutch off
I suspect the 1F1 addressed messages you suggest are the ones I am looking for.


antus wrote:You guys may be aware, but if you are not the GMLAN bible here covers a lot of IDs. I am not sure if it covers what you are looking for. https://docs.google.com/spreadsheets/d/ ... edit#gid=1


Acknowledged the GMLAN bible, the the HS 11bit information is incomplete and not very helpful. Hence, why we are here :)

ironduke wrote:I even found a bin with your OS and tried it and it does indeed change request from no to yes!!


I tried sending 1F1AE1600000800007A and it did not engage the ac clutch. However... my a/c isn't gasses up at the moment so may be failing the AC pressure test. maybe? Using HP tuners to monitor, I can see that the "AC Disable (pressure)" is set to Yes which supports this.
I may need to wait until I have the ac system gases unless the gas pressure can be spoofed.

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Re: E38 HS canbus messages

Postby ironduke » Wed Nov 11, 2020 10:23 am

What else do you have available besides hptuners? Do you have a gm MDI?

can you monitor a/c request with hptuners? that should change from no to yes when sending that command, that is what I am seeing with tech2win..

You probably wouldn't see the clutch engage unless your meeting all the criteria, if your system has the 3 wire a/c pressure switch on the high side I assume low pressure would keep it from engaging..

I am very curious if this works, seen it mentioned quite frequently as people are wanting to be cool in their swaps..

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Re: E38 HS canbus messages

Postby snap » Wed Nov 11, 2020 10:42 am

ironduke wrote:What else do you have available besides hptuners? Do you have a gm MDI?

can you monitor a/c request with hptuners? that should change from no to yes when sending that command, that is what I am seeing with tech2win..


hptuners has the following channels that can be monitored.
    -AC Clutch Engaged
    -AC Serial Command
    -AC Disable (WOT RPM)
    -AC Disable (Pressure)
    -AC Pressure - pressure
    -AC Pressure sensor - voltage

I have also have a VCX nano and tech2win. I'll hook it up and see what I get.

As you say, I assume the ecm is not happy with the 3 wire a/c pressure switch reading.

ironduke wrote:I am very curious if this works, seen it mentioned quite frequently as people are wanting to be cool in their swaps..


I am one of these swap people and I hope we can get to the bottom of this. Thanks for you all guidance so far.

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Re: E38 HS canbus messages

Postby snap » Wed Nov 11, 2020 12:06 pm

For anyone interested the PRNDL.

Message id's with ID 1F5 have the PRNDL shifter status (great to know if you 6l80/T43 tcm sends reverse status over gmlan)

byte 4 is the status

1F5 0F0F000100000300 - this is Park
1F5 0F0F000200000300 - this is Reverse
1F5 0F0F000300000300 - this is Neutral
1F5 0F0F000400000300 - this is Drive

1F5 0F0F002100000300 - this is Park (ignition off)
1F5 0F0F002200000300 - this is Reverse (ignition off)
1F5 0F0F002300000300 - this is Neutral (ignition off)
1F5 0F0F002400000300 - this is Drive (ignition off)

My question is: does the BCM use this PRNDL message to determine when to turn the on reverse lights? i.e. is this what is used for the by the BCM for reverse signal? When I connect my BCM, it does not turn on the reverse lights.
I know the circuit works because when I send the device control message to the BCM 241 07AE120101000000 to test the reverse lights, the reverse lights work. Not sure why the BCM is not picking up the TCM/ECM reverse signal.

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