ECU checking... next step from here?

[jwwpua]

I'm trying to access the ECU on my 1995 240sx. I know how to read the ECU light for codes, but I'm not sure exactly where to access it. Where do I go from here? (pic)

thanks



p.s. I read a howto from a 240sx.org FAQ, but I don't see which screws I take out to access the ECU (light and mode selector).

[jwwpua]

Can someone please point me in the right direction? I removed the screws that hold it against the sidewall, but I don't see the red LED or mode selector. Where exactly is it?

thanks

[KRUZNBY]

I think there are 3 screws to get it out. Then there is a screw on the back side that you have to turn to put the ECU in diagnostic mode. What a great design by Nissan so that you have to remove the ECU to do the diagnostics. Look in the FSM for more details.

[Silvia2b]

Yup there is thee fasteners two bolt/scews and one nut then, mode screw and the LED are located on the end that faces the firewall. let us know what code you pull and what is causing your CEl/MIL to come on.

[jwwpua]

Thanks for helping me with the ECU (or is it ECM for this car?). It gave me a code 34 (knock sensor). I reset it and drove for a day to recheck it. It gave me 34 again. What's my next step? And what would a faulty knock sensor affect?

thanks

[Silvia2b]

Probably you need to check out the wiring harness and the knock sensor itself. You can read how to do this in the FSM pages 130-134 of the EC section. You'll need a sensitive digital multi-meter to test sensor with continuity check/impedance (M ohms) for harness. I think the knock sensor detects when the engine knock occurs and the ECU then retards timing to prevent damage. This will also effect you fuel mileage/performance, obviously.