Issues with a P12

[Jabbott]

I know it a old setup but having some issues with my sons 06 H3. You can't read it through the OBD but pulled the ECM and bought 2 spares as well. The bench harness used from the E40 which has the same pinout will also not work. Not even finding the ECM. i looked at the bench harness and then compared pins to the P12 and E40. They are all the same except the pin 1 and 2 which is Can+ and Can- on the E40 but the P12 does not have CAN so I would not think this is an issue. Everything else is in the same spot. It will not work on either of the 3 ECM's so it tells me it is a comm issue since the truck will run on the current ECM and it will scan in the truck. Any help on this is appreciated.
Thanks
Justin

[blindsquirrel]

You have something other than HP Tuners to do the initial programming? That PCM has 8 segments in it, but HPT tune files only have 7 (no Electronic Throttle Control segment).

[Jabbott]

You have something other than HP Tuners to do the initial programming? That PCM has 8 segments in it, but HPT tune files only have 7 (no Electronic Throttle Control segment).

I have EFI Live as well but it has the same issue. I can't even detect the ECM on the bench which I went through the pinout and it is all correct. If I leave it in the car it will connect but it stops communicating about 26 seconds into it and goes into failure on just the read. Everyone has said you need to but these on a bench and read them but can't communicate with it like that. I know the P12 does not have CAN but the connector for the E40 is the same pinout minus the CAN. It will not communicate at all. I am at a loss here. Both HP and EFI list this vehicles as one of the ones they work with but neither seem to do. I curious about the TBSS, didn't that also have a P12 in it on some of the years. My son was thinking about getting rid of the H3 and getting one of those, but we may be re thinking this now.

[blindsquirrel]

Even if you solve the no-comms issue you still will not be able to do the base level OS-change-from-one-platform-to-another programming it sounds like you are wanting to do, if your only tools are aftermarket tuning stuff. These have to be initially programmed using GM SPS and some flavor of J2534 tool.

V8 GMT360s were CAN-based, E40 for '05-'06 and E67 '07-up. Only the 4/5/6 cylinders used the P12.

No way am I going to slog through comparing the entirety of the pinouts, but I did take a quick glance - and right away I see that P12 has Ignition 1 voltage at C1 13, but E40 is C1 14. Since you didn't mention that as being different maybe you need to spend some more time getting the pinning correct for the thing you're working on.

[Jabbott]

Not trying to change a OS, right now we just want to raise the idle. The harness uses pin 19 as ignition voltage. The P12 does have a ignition voltage on 13 vs 14 on the E40 but the Speartech harness does not use 13 or 14. It applies voltage at 18,19 and batt at 20. It gets the low reference at C1 pin 7 and a ground at C2 73. The Serial data is C1 pin 15. I don't see where the bench harness is incorrect but I am not able to read it. Per EFiLive the bench harness on the E40/LLY and the P12 is the same harness. If I install a E40 on the harness I can read everything just fine. I have three P12 ECM's here and none of them turn on so this is a comm issue I am 99% sure, but not sure where the is.

[Jabbott]

Ok, so the speartech harness is not wired the same as some of the other harnesses. Theirs is a E40 only and I guess I mis interpreted the way EFILive was saying the E40 and the P12 were the same. Same connector but unless the bench is wired with both the serial data and the CAN +/- it will not work on both units. Working on a P12 harness now and we will see what happens after that.