Note to anyone with an undiagnosed 240SX problem

[93vert240]

Struggling with and undiagnosed problem myself I thought I should tell everyone the biggest time saver in the world...

My 93 240 was running poorly and I had already replaced numerous parts and was extremely frustrated when I heard about the greatest thing in the world.. The ECU Self Diagnostic mode.. The ECU is located on the passenger side of the car just left of the door behind a removal panel. To access it you must remove the sill from the doorway (held in by several plastic screw clips) and pull the little panel which goes from the sill up to the dash. Behind this panel you will see a metal box with 86 in large letters on the side (possibly only a 91-94 240SX thing). There are 2 bolts holding the ECU to the side of the car (one above and one below) which take a large phillips head screwdriver to remove. Once these are removed you will have to carefully jiggle the ECU out of its mounting area and turn the side facing the engine bay towards you. You will then see a single flathead screw which is underneath a hole with a red LED inside it. Turn your key to the on position (all dummy lights on dash should be on) then proceed to turn the flathead screw (dont force it if it stops) fully clockwise. Wait 3 seconds! Turn the screw back counterclockwise til it stops and look at your check engine light.

It should flash a code to you, for instance
blink......blink......blink......blink..blink..bli nk would be 33
(the slower blinks being the first number and the faster blinks being the second)
note: If there are 2 distinct numbers that means you have 2 seperate codes

Also note that your check engine light does not need to be on while you drive for you to have an error being reported to your ECU.

The code meanings can be obtained here http://www.emergent.com.au/200sx/ecucodes.html

Don't Forget Your 240SX Is Your Friend And Will Tell You What's Wrong If You Ask It :blah:

This is strictly for OBD-I cars (before 1995) it may or may not work on post 95 models although I have no way of checking on that.

Thanks to anyone who reads this and I hope it helps you as much as it helped me. After all, who says you need to pay someone 50 bucks to tell you what you can find out yourself.

[theicecreamdan]

works the same way for OBD2

[Zilvia]

alright coo... thanks

[Dousan_PG]

is this a sarcastic post or real?
because the first think one should always do is check codes
and own an FSM

[infinitexsound]

yes dousan this is a real post i assume... its funny but shouldnt everyone own a FSM GET IT IN ADOBE, or buy the book like i did....

[kandyflip445]

I have two FSM books. lol One came with the car and I got the other from a friend. :p

[SochBAT]

i borrowed my buddy's. He's never gettin it back.

[borohingacoupe]

Downloaded mine from the net. It's helping, but i still haven't solved my idle issues, going to attack it hard in the next week or two. Working 6 days a week leaves little time for wrenching.

Matt

[krustindumm]

I look up mine at work, ESM or FSM, and i have a copy of the ESM at home.

Really though, if you didn't know your OBD1 equipped car had on-board-diagnostics, it must have been a hella heavy rock.

[Dream240]

Really though, if you didn't know your OBD1 equipped car had on-board-diagnostics, it must have been a hella heavy rock.

Heh...that's a good one. But really just look at the poster's history. This is clearly a :newbie: post and he's just trying to help out all those 240 newcomers.

Just a side note: if your ECU flashes a 55 code...then all is well. So really if you've got a problem with your car and the 55 code flashes then it's basically saying that the short list of components on the OBD-I code list are functioning. So that leaves you with oh about 30 other things that could be broken. HAVE FUN.... :)

And yes this method will work for ALL 240s.