Rear o2 sim

[ob1]

I have a 95 240sx with hotshot header and recently my check engine light came on code 77 rear o2. I put a o2 sim in place of it but did not help there are 3 wires power brown, white signal and the 3rd black I have o2 sim connected to the brown and white what do I connect the black wire to is this the heater wire. I read some where I'm suppose to use a resistor on the heater but what ohms and wattage?

Modified by ob1 at 2:14 PM 10/29/2007
Modified by ob1 at 5:46 AM 11/1/2007

[Ligouri Rd]

I needed to leave the o2 sensor connected so the ecu still saw the same current draw...I imagine that could be faked with a resistor but that smacks of effort.

Anyhow, the two white wires are connected to ground, tap into either one for the o2 simulator's ground. The brown wire is the heated o2 sensor power, I would connect that to both the power for the simulator and the original sensor. The black (with white stripe) is the 02 sensor signal, connect that to the o2 simulator signal only.

[ob1]

Thanks for your reply but have a few questions. First the white wire coming from the ecu you said ground it the fsm says and I also measured it has 3.5v coming out of it and the black wire has .02v ok what the fsm says is the white wire should be below .55v at least one time then .6v at least one time this is why I connected the sim signal wire to the white one. I want to eliminated the o2 completely that is why I installed the sim but thanks again for your reply.

Modified by ob1 at 2:17 PM 10/29/2007
Modified by ob1 at 5:47 AM 11/1/2007

[ob1]

Help anyone.

[ob1]

Ok for everyone that is interested I've figured it out the wiring and all. The wires from the harness (wires car ecu) are as follows brown to red on o2 sim. White wire from ecu to o2 sim white wire only. Black with white stripe wire from ecu to 6ohm 10watt resistor this goes to the brown wire (harness side) as well . The black wire from the o2 sim goes to ground. This set up has worked and has completely removed second o2 sensor.

Modified by ob1 at 2:22 PM 10/29/2007

Modified by ob1 at 2:26 PM 10/29/2007
Modified by ob1 at 5:48 AM 11/1/2007

[Chaotic_Warlord]

Where did you get the o2 sensor and how much was it?

[ob1]

I made the o2 sim from a 555 timer chip this cost me around twenty bucks parts and all then you have to put it all together. You can google o2 sim this should bring up a web site that you can purchase pre made o2 sims. The sim completely removes second 02 sensor and sends signals to ecu so the check engine light does not come on.

Modified by ob1 at 2:34 PM 10/29/2007
Modified by ob1 at 5:49 AM 11/1/2007

[jg61022]

HI, I am having problem with the rear o2 as well. When I measured the voltage going to pin 52 of the ECU, white wire, O2 signal, I got 9.8volt-I know that'sway off, it should have been between 0-0.66voltWhen I measure the voltage going to pin 108 of the ECU, blac/white wire, I got 12.3volt-It's that correct? What should be the voltage going to pin 108?I want to have an O2 sim and remove the rear O2 too.You said you have to install a 20ohm20watt resistor between the black/white wire from ECUand the brown wire to the harness, do you cut the brown wire to the sensor? Thank you very much

[ob1]

Sorry I have not been on here for a while email me and I will tell you all you need to know its on here just look @ my profile

[ob1]

bump