1993MaxSE

I've searched and found pretty good directions at getting out codes from my ECU, but there's something I'd like to clarify before I go try it: I am getting terrible fuel mileage and I think a sensor (knock or O2) is going, but I am not getting a check engine light. Does the ECU give some error codes without the check engine light coming on when driving? Or would I be wasting my time to mess with the ECU if I am not getting a check engine light?

maximalover

I wasn't getting any engine check light.

I got the FSM recently. So I set out to try couple of things in the FSM. One of the things I did was to check the trouble codes from the ECM.
I checked the LED on the ECM. I read code 33.
Surprisingly I was't seeing the Engine check light on during normal run of the Car.. I am getting around 23-24 miles per galon.

I think it is decent. But code 33 is a indication fualty O2 sensor. I have to check the O2 sensor

If there is no problem then the ECM will read 55 on the LED..

So if you have the FSM it is easy to check the codes from FSM..

Hope it helps

1993MaxSE

Thanks, I need to pick me up one of those FSMs! Time to look on eBay...

i_canoe

So what is a FSM?

Sudesh

As long as you didn't disconnect the battery, you can read whatever codes are stored in the ecu. The engine light doesn't have to be on for the ECU to have already stored a code.

i_canoe - FSM means Factory Service Manual, it's the book nissan writes about your car describing how to do everything to it, step by step. Get one.

1993MaxSE

Hmmm, I've disconnected the battery a few times recently. Tried a friend's battery in my car to see if it affected the problem (it didn't) and also installed a JWT intake. Hopefully if I drive around for a few days without disconnecting it first, then check the codes, I'll come up with something. Good to know.

Also, yes FSM = factory service manual, and I've got dibs on the one for sale on eBay right now that ends in 3 days!!! Please let me have it!!! I really need it!!! :-D