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Trying to find Codes: Diagnostic Port


Jon89le

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The car is a '94 Z34. Im trying to find which pins in the diagnostic port need to be jumped to trip the ECM codes. Anyone know? If you dont know, anyone know if jumping the wrong two pins can cause any damage? I took a look at them and there are three pins in the corner so if no dammage can be done, ill just figure it out by trial&error. Also, i have a code book from my OBD1 cheap $20 scanner for my '89GP. Will those same code#'s apply to the '94Z34? Thanks

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'94 is the oddball year. OBD1 connector w/ OBD2 brains. Jumping simply won't work. Have to read it with an OBD2-capable scanner with an OBD1 connector.

 

But it being a Lumina, I wouldn't say for sure the above is true, as they didn't receive the new 3.1 until '95, whereas the other 3.1's across the line (with the odd OBD) received the updated engine.

(I know you have the 3.4, but they may not have changed the OBD at that point, considering GM didn't update anything else in the Lumina that year.

 

Someone will correct me.

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Guest Anonymous

If the 94 Z's were OBD I still then it's the two terminals in the upper right hand corner. And the codes would be the same as your 89 GP.

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I just tryed my scan tool and it didnt do anything. Any ideas?

 

Like I said above, its more than likely an OBD2 system. You'll have to have a shop scan it, unless you have an OBD2 scanner.

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It's not an OBD2 system.

It's OBD1, but a weird one. Very similar to a 7727 ECM used in the past, but supports SFI.

There are no diagnostic pins even on the ECM itself, that's why there are no diagnostic jumping pins in the diagnostic connector.

 

Sorry, you're SOL.

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It's not an OBD2 system.

It's OBD1, but a weird one. Very similar to a 7727 ECM used in the past, but supports SFI.

There are no diagnostic pins even on the ECM itself, that's why there are no diagnostic jumping pins in the diagnostic connector.

 

Sorry, you're SOL.

 

I thought it was closer to the OBD2, but still ran an OBD1 connector? I know its not a TRUE OBD2, but most of the system ran like one.

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No, it's still a P4 PCM. It doesn't have flash ROM or anything like an OBD2 does. It also doesn't support the Class2 data bus like OBD2.

It's just a weird one.

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