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When using the 12P can trouble codes be retrieved by grounding the a-b terminals in the ALDL and counting the flashes of the check engine light. I ask this question because I assume a scan tool is not an option for diagnosis here in the states. I know your thinking why would a person want to do this when there is a comprehensive tuning program to use for diagnostic. It is because if I ever sell the vehicle one of the buyers questions will be can the engine management system be diagnosed by an average auto technician.
Thanks!

It can.

Both 11P and 12P give the same codes as any Delco system. I have a Autell scantool and it works with both codes but the paper clip id an option as well.

Hey guys thanks for the info. What car do you tell your autel your working on and does it also display data ?

The scantool is Autel MD802 but I found that they have deleted Holden from their list and I can only do it with a very old version of their software. I tried my Vpecker and it won't link so it looks like a paperclip in the diagnostic plug and no live data. I do know that the older Launch tools can do it but it looks like their only interested in OBD2.

It's better to post the same issue in only 1 section. Saves a lot of doubled up info/ confusion.
They are related?
FS: ECM NVRAM Conversion (VN to VS but not VS Ecotec)

12P is based on factory code $12 and 11P is based on factory code $11. You can see what cars and models and applications used $11 and $12 here. Picking any of those in your tool will work. https://pcmhacking.net/memcals.html Mostly Holden VR Commodore 11=auto, 12=manual, with some exceptions.

Since the OP is in the 'States, the ECM is probably a '165 rather than an '808. This means that the ECM includes the ALDL interface circuit, which is wired to pin A8. If the wiring harness brings this line to a suitable ALDL connector, perhaps 12 pin or "OBD 1.5" (16 pin), then there should be a suitable ALDL "cable" available with which data can be read using software such as TunerPro RT.

Joe.

Thats correct but it doesnt change my answer to his question The VR has the later variant with ALDL too (same as the '165), and thats what its talking on the bus. Thats what he should tell anyone who wants to use a scantool.

Looks like the ALDL is different on the US cars. We grounded the diagnostic terminal and counted flashes for years until scan tools were available. If needed we could change the diagnostic connector or make jumpers and use a scan tool for a VR. Thanks for the info!