GM Can to ALDL

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Tre-Cool
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Re: GM Can to ALDL

Post by Tre-Cool »

the issue is the can gateway in the vz only works with the earlier can protocol. so using early tcm/ecu will likely talk to the abs module & dash fine.
ben_att
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Re: GM Can to ALDL

Post by ben_att »

This is true, however I can’t find a VZ OS that will communicate and control the 6l80, my VF’s with the 6l80 are so much better to drive and so much more responsive than the old 4l60 which is why I don’t want to go back to the VZ software. I can drive the VZ I’m playing with now and although I have no Speedo or tacho, it is so much better to drive than the 6L crewman with a 4 speed. Additionally the motor I put in is the L77, I don’t think any of the VZ’s came out with any of the DOD or flex fuel etc either which is another reason I wanted to keep it running on the VF ECU.
I found another thread last night on here where there is someone who developed a BCM/PCM simulator and someone was asking similar questions to what I’m trying to do, so at least I’m not the only one :lol:
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Re: GM Can to ALDL

Post by antus »

I think making some version of your own pim might work. the hardest part would be getting the timing right and syncing your transmission on the ALDL bus which is very busy without a collision on the ALDL side. You might need to shoot for the gap that logging software uses to silence the chatter, and if you transmit in that gap the you will probably loose the ability to log. I think the pro micro and MCP 2515 might be fast enough to keep up. You can look at the docs for the auto_wp can library and see if you can implement a filter in the MCP 2515 to take load of the pro micro cpu. The cool thing about the pro micro is it has native usb for the pc side when your developing and a hardware uart which helps a lot with reliable aldl. It seems to do 8192 baud fine. I had a lot of trouble with software serial implementations before I settled on the pro micro hardware. The software solutions say they cant transmit and receive at the same time, which is exactly what aldl echo looks like. Some people seem to have gotten it to work, but I not me. There is also the esp32 hardware which has uarts and can, but you still need to add a can transceiver between the esp32 and the can bus. pro micro + mcp 2515 ticks the boxes easy, though. You might also be able to have your own aldl bus just between the pro-micro and the dash, to avoid bus collisions and allow the vehicle bus to function normally.
Have you read the FAQ? For lots of information and links to significant threads see here: http://pcmhacking.net/forums/viewtopic.php?f=7&t=1396
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Tre-Cool
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Re: GM Can to ALDL

Post by Tre-Cool »

ben_att wrote:This is true, however I can’t find a VZ OS that will communicate and control the 6l80, my VF’s with the 6l80 are so much better to drive and so much more responsive than the old 4l60 which is why I don’t want to go back to the VZ software. I can drive the VZ I’m playing with now and although I have no Speedo or tacho, it is so much better to drive than the 6L crewman with a 4 speed. Additionally the motor I put in is the L77, I don’t think any of the VZ’s came out with any of the DOD or flex fuel etc either which is another reason I wanted to keep it running on the VF ECU.
I found another thread last night on here where there is someone who developed a BCM/PCM simulator and someone was asking similar questions to what I’m trying to do, so at least I’m not the only one :lol:
yeah what you would need is to convert late can to early can & back for abs, along with can to aldl for the dash cluster.

i got lucky with the vy as the abs pretty much works standalone just fine with no input from anything.
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Re: GM Can to ALDL

Post by Madchuska »

antus wrote:Completely unrelated I built a 5v arduino pro micro + mcp 2515 to try and do aldl to can (rather than the other way around) for a can data logger to work on 12P. I got it working on the bench properly, then it kinda stalled and thats where its sitting. The speed is pretty slow, though its hard to tell if thats more in the elm clone I was using to test it, or the pc software. In theory it should be able to handle 5-8 60 byte ALDL frames a second on the aldl side, and plenty of requests on the can side. In practice I think the issues were pc app + elm, not the board I built. Can share more details if you want a starting point to build your own tool for your purpose, though you can see what the hardware should look like from the code, which I have attached.

This is great, I started going down a similar path and was doing some basic testing in the car but it never really went any further.

At first I was trying to pick-up the CCM A/C request frame in a VX then transmit via CAN to my Aftermarket PCM. - I was able to get this side to work.

The Aftermarket PCM also transmits the A/C Status via CAN so I wanted to receive this and then transmit it via ALDL in the 41 broadcast frame so the CCM knew that the A/C was enabled. (this seems allow you to use the "Auto" function on the CCM module - Yes I know its a silly want...) I have a feeling that the CCM also wants the A/C pressure for some reason this is also transmitted by the Aftermarket PCM is is possible.

Another one in the 41 broadcast frame is Low Speed Fan Control so If the above is possible to get working I was also hoping to do this.

The last 2 points is where I got stuck, The PIM is still connected via ALDL but not receiving anything on the ECU side so in my case it seems to almost be transmitting random data.
An alternate idea was to have a CAN to Class2 module but this seemed to be harder to find info on and I don't have the tools to sniff it.

At this point in time I think the only reason the PIM is there is because from memory the car wouldn't start without it. I could possibly just wire the Start wire to the aftermarket PCM and remove the PIM all together.

Any suggestions on what else the PIM could be doing?
Am I one the right track with the ALDL side or would you look to use a different PIM or the Class2 option?

Thanks in advance
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Re: GM Can to ALDL

Post by ben_att »

Well I thought I would just try something out of curiosity and lucked in and have a working speedo and tacho now. I just tried throwing a wires onto some pins that had no wire connections to them on the VF ECU which but are in use on the VZ ECU and with a couple of small changes made in HPT it works.
So I've got the Tach working from pin X1-48 by changing the setting 'Tach output type [ECM 701]' from 'serial' to 'crank' and it looks to be very close to what I'm seeing on VCM Scanner.
The speedo is working, but is still a little out, I picked up pin X1-57, I had to change the diff ratio in HPT to suit the car, drove it watching VCM and a GPS to get them the same (crude but only temporary) then reduced the PPK in the cluster, originally it was 6175, and the speedo was a bit over 50% out, so I've dropped it to 3000 and it's much closer but still out by about 10-15% but I can't seem to reduce it any further, AA software just changes to 3000 if you try to type anything lower and if I try and send the command via OSE it changes to something totally different to what I think I'm sending it. So if I can't get around that, might have to put a converter box in that'll correct it as I wanted the VCM speedo to be correct so the trans shifts etc are correct.
The other thing I'm curious about, is although the ECU is from a VF, in my other VF's, there are extra options in the HPT speedo page such as 'speed data type' which options of 'CAN Late, CAN early and class 2 bus', be interesting to see what effect this would have on the VZ, but these options aren't in the OS that I'm running. OS I'm running is 12656930, LS3 OS 1265778 gives more options.

The next one was the radiator fans on the VF are run off a PWM module that is controlled via one wire from the ECU (X1-58), however I added another wire to pin X1-17 which has no connection on the VF ECU, changed the fan type from 'PWM Electric' to discrete and no of fans to 2, played with the state tables and it works as it should with the two stage radiator fans. The only strange thing I noticed with this, is if in the temp tables if you have 89 or maybe even 91 degrees set to anything other than 0, the fans stay on all the time, even after changing the settings back. As soon as the fan logic startup delay had expired and the engine was running, the desired fan speed was always stuck on 91%. I even tried changing all temperatures to 0 and no good, I could change the output state vs control to 0 which would stop the ECU picking up the relays, but still had 91% desired speed so obviously like this, the fans will never work, so the ECU still has control of the relays but something weird happens with the ECT vs fan request logic. I had to rewrite the OS into the ECU using SPS and make sure those two were set to 0 before rewriting a tune in with HPT and that corrected this.

Now to continue on with the ALDL to CAN conversion, as soon as the dash cluster sees RPM, it comes up with alerts for oil pressure, alternator voltage etc because it's not receiving the right data. Also fuel gauge data doesn't come through, I can see a reading on VCM scanner as the gauge is wired into the ECU and the resistance values looking at the service manuals have the same range, so hoping for the best with this too. I'll hopefully sort this first, then onto the A/C and ABS.
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Tre-Cool
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Re: GM Can to ALDL

Post by Tre-Cool »

i didnt realize you were having those issues. i could of just told you to add the wires. lol everything is pretty much the same still on ecu's from vz to vf.

something else to consider for the fans is the aircon pressure sensor, if that is unplugged that can keep fans on too because it think's pressure is too high.

also, ping 16 on the 6l80 is a replicated tos pulse. i think i used that for my speedo.
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Re: GM Can to ALDL

Post by ben_att »

Ah right, I couldn't find much info online if it was the same or not, but lots of people saying along the lines of 'it's all different and won't work'.
The tacho signal doesn't work unless you change the output on the ECU from serial to Crank though (in my case anyways). The speedo signal was enabled already but gives me a signal very different from the VZ OS hence the very different reading in VPW scanner which is accurate to what I'm seeing on the cluster which is not.

I did think of that, but with mine disconnected the pressure is reading as 0? (and I changed the fan states all to 0 in HPT for AC pressure while testing and it made no difference) I did see something on the HPT forums where others were having similar issues where the fans are always on but there was no result, luckily flashing it with SPS wrote over what ever HPT did that upset the code in my case and that's resolved.

On to the next thing, is there major differences between the VY and VZ clusters? I can send commands to get the fuel gauge / temp gauge needles to move on the VY cluster, but sending the same commands over OSE to the VZ cluster doesn't seem to have any effect? Is the VZ cluster using a different protocol?
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Re: GM Can to ALDL

Post by yoda69 »

For fuel VY cluster is hardwired to the sender.
VZ gets fuel gauge info from the ECU which I imagine will go through the PIM and be converted to ALDL for the cluster.
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Re: GM Can to ALDL

Post by ben_att »

Yep, fair point on the fuel gauge, what about the temp gauge though?
Looks like it's still serial to the cluster on VY as well, is it?
Does the cluster request messages from the ECU or is it just picking up data that is being 'broadcast'?
I found a copy of this GM can data info (attached) which is sort of helpful for the newer stuff, but I can't find a whole lot of detailed data on the ALDL yet.
For instance, how often does the dash cluster look for updates on the temp, fuel gauge, oil pressure, alternator voltage status etc?
Is the dash requesting this data and then generating a fault because of no reply or is it generating a fault because it's not seeing data on the bus that it wants to capture? I would go for the latter because when I hook the dash up on the bench, there's nothing happening on the line that I can see when monitoring it when all the errors are showing up.
Are the commands sent via AA for testing the gauges different to what's being sent in the car?

for eg.
sending F2, 83, 04, 00, 00, 00, 00, 00, 00, 00, 00, 00, 04, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 0C, 00, 00, 00, 00, 00, 00, 00, 00, 40, FF, 00, 38 to a VY cluster will make the fuel gauge read at approx. 1/4 but does nothing on a VZ cluster.
What I notice too is sending the above command it will hold the needle in that position for approx 6 seconds, so does that mean if I can work out what I need to send I can broadcast the levels in 4 second blocks for instance and the needle won't 'hunt' it will stay at the last given signal for the period of time?

If I can't work out the VZ ALDL commands, might be easier to put a VY dash into it, since I can hardwire the fuel gauge, then I know what I need to send it to make the temp gauge work, but then I'm not sure what effect that will have on the SRS and ABS. Shame the plugs are different or I'd just drop the VY one in and see how it responds, might make up an adapter loom and see what it does.

Otherwise, am I looking at this the wrong way, does the BCM send the data out to the cluster and not directly from the ECU (via PIM)?
Also, on the schematic I have, it shows a contact in the BCM to make or block UART connection to the rest of the car from the PIM, can't find explanation anywhere of the purpose of this or what makes it change state.
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