There are 3 grounds going to the ECM
( at this point)
All Black/white tracers ( crkt 450 )
D3 & D10 ( on C1 )
A12 ( on C2 )
These are the 2 connectors on the ECM
C1 is the BIG connector (16 pin dual) Series "C&D"
C2 is the small connector (12 pin dual)Series "A&B"
These wires splice ( in the harness) at S 111
( for the Mass airflow sensor/Mass airflow relay/fuel pump relay/& tranny position sensor, assuming automatic)
The S111 splice is buried in the harness at the firewall feed thru behind the right hand cylinder head ( Not a pretty job)
Which ties to......
G-104 ( left side of engine by Oil temp sensor,
Big godzilla lug with other grounds on it)
The G 101/G-104 jump from the Engine Block ground Braid to the FRAME ground to the Battery Neg Small lead. The FRAME point is about under the Vac booster for brakes ( a little foward ) this ground point always gets rusted up!
There is a TAN wire on Pin D-6 of the ECM connector ( C-1 ) which has a home run to the G-104 ground point.
There should be a total of 5 Big lugs on the LEFT side of the engine.
Braid to ground
Batt big Neg cable
& 3 wiring harness lugs
on the engine side (7 wires I think) on the G-104
(engine side ground point)
yeah i think that pretty much covers it. my vette is an 86 coupe.
hoping i have a grondig problem. not getting reading on my scan tool from the MAF,TPS, IAC, and the car is running in an constant open loop, thanx for the info vigman