VP 5lt conversion to HQ

[Outlaw327]

Can anyone steer me in the right direction on trying to read error codes on my VP 5lt in a HQ , trying to determine if I can read codes by connecting a light to read codes in diagnostic mode , thanks

[Charlescrown]

Theres a few guessing questions that need to be answered.
What is the number of the ECU?
Do you have a check engine light wired into the car?
Do you have a diagnostic plug fitted?
I have added a pic of the diagnostic plugs fitted to early and late Delco systems.

[Outlaw327]

the only sticker left on the ECU is a bar code and number on the side of the long black plugs (952101101390036)
there is no check engine light wired in ( would be helpfull to know how to wire one up )
the factory 6 pin diagostic plug is in place
cheers

[vlad01]

The diagnostic plug on the harness, the 6 pin I think should have output for a CEL. I have used this on my nephews 4Runner as whoever did the Buick conversion never wired half the stuff to the car.

[Charlescrown]

What Vlad said is correct.
Going off the 6 pin ALDL connector.
If you wire up a low current light (I use LED with dropping resistor) with the negative going to terminal E of the 6 pin plug and the positive to a 12 ignition on power. Any low current 12 volt light will do so polarity won't matter.
Then all you do is bridge B and A and the light will start flashing a code. eg flash pause flash flash is code 12 all OK.

[Outlaw327]

Charles crown , thanks for the info , also wondering if anyone in the Canberra area can still access these old Ecu to test for any internal failures ?
Cheers