so, i decided to change out the battery harness to a s4 t2 and wondering what the round black plug on the body harness side is for. also there is a black 4 prong plug from the t2 harness side but everything else is white on the body harness

the car was originally a s4 na automatic and never changed out the body harness. i kinda dont wanna **** **** up at the moment so i just need a quick answer or verify what those plugs are.

 

Depends. On eighty seven turbo models there's a black round plug with one black/white wire and that is the wire going to the starter solenoid. That plug did not exist on early eigtht seven cars that are non turbo.

See page 50-14 of the online wiring manual to see that plug on TURBO cars.



Just go to the online wiring diagrams and look at the plugs there and compare the colors in those plugs with what you have.

Page 50-36 of that manual shows a round four wire plug for NON TURBO cars with the black/white wire for the starter solenoid.........a black/red for the subzero starter system.........a black wire that is probably a gnd wire for ????...........and a red/white for the oil level sensor/gauge. That round plug ..........one half is on the front harness and the other half is on the engine harness.

There is no BATTERY harness on this car. That is the ENGINE harness. See page 50-116 for what is on the ENGINE harness and the following pages for what harness is which on a RX-7