ABA OBD1 ECU 33; connects to block? (ground)

[Vanagon Nut]

Hi folks.

This is for the ABA Motronic 2.9 OBD1 ECU and engine harnesses.

I'm nearly certain the answer is "yes" but....

Does ECU 33 connect to engine block ground?

Or, does ECU 33 "supply" a ground to the negative side of that circuit(s)?

Alternatively, if someone had these harnesses, could they please connect the round 28a connectors and measure for continuity between ECU 33 and any of the copper ring terminals at end of engine harness?

I've spent some hours studying the ground paths as shown in the A3 Bentley, A2 Resource, the well known .edu 1995 diagram but looking at those, and harnesses in hand, (which have been cut, repaired, being repaired), i'm still not certain of where this ground comes from.

Much thanks

Neil.
_________________
1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[Vanagon Nut]

Never mind. Forgot about the test table in Bentley.

P. 24a-13 shows ECU 33 as a 'main ground' and volt meter at ECU 54 (B+) and 33 should show approximate battery voltage.

Neil.
_________________
1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN