So I am going to be doing a B series swap in my 99 civic hatch soon. So I got myself a 99 00 Si engine harness. My question is, where is the the wiring for the second (downstream) O2 sensor? This is going to be a daily driver so I need both of them hooked up. I've been told its in the main dash harness but where do I start looking?

Thanks for any help

 

on the catalytic throught the floorboard above the shifter and plugs in the cabin harness

 

It's a DX (no hole in the floor) so where on the cabin harness is it? I know the wires are there they are taped to harness somewhere but are they up behind the radio, underneath the console or someplace else.


Modified by El_Capitan at 6:17 PM 1/14/2006

 

up

 

You will need to make your own wiring harness for the secondary o2 sensor and run it through a hole in the floorboard.

Wire it as shown:





Wht - A23
Grn - C18
Blk (O2 heater control) - A8
Blk (O2 heater supply) - use a switched +12v.

 

On your hatchback the secondary o2 sensor plug was on your main engine harness because your secondary o2 sensor placement was near the same place as the primary o2 sensor on the exhaust manifold. On Ex and Si it is on the cabin harness because the secondary o2 sensor is on the cat underneath the car. It would be easier for you to re-use your stock harness and modify/add a few plugs.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by El_Capitan &raquo;</TD></TR><TR><TD CLASS="quote">It's a DX (no hole in the floor) so where on the cabin harness is it? I know the wires are there they are taped to harness somewhere but are they up behind the radio, underneath the console or someplace else.


Modified by El_Capitan at 6:17 PM 1/14/2006</TD></TR></TABLE>Actually, there should be a hole in the floor (on the exhaust tunnel to be exact), even if it is a CX/DX, its just has a rubber cap over it.

And like EK k kay said, the OE harness and plug for the DX secondary sensor would be on the engine harness since the cat and both O2 sensors are towards the fron of the engine bay. It would definitely be easier to snip/splice into those wires at the ECU connectors.

Your other option would be to disassemble/unwrap the entire harness and have the O2 sensors go where you want, then insulate everything again.

 

Thanks for your help i will just make a sub-harness and run it along with the main engine harness. Is there a pin that I can use for the switched 12v source? what do you recommend?