Check Engine Light

citrus3000psi · Post by **citrus3000psi** » Tue Jun 09, 2009 4:05 pm

On the ecu what does it output, +12, -12? Reason I ask, I tested my ecu the other day, and couldn't get any volts out of it. My diag wire works, i can read codes off of it, so I know the ecu is booting and working.

But still can't get anyhing out of the CEL, any ideas?

jeffball610 · Post by **jeffball610** » Tue Jun 09, 2009 4:27 pm

Get a data logger. This is a cheap and essential investment in your 4G63 powered vehicle. The output is 12v from what I can tell. You can use an electronic buzzer tool to help diagnose the CEL codes.

http://www.vfaq.com/index-main.html

Under "Electrical" and "Retrieving Diagnostic Error Codes" there is a write up of how to perform this simple task. Bookmark VFAQ.com as it is essential to your DSM and 4G63 modifications.

citrus3000psi · Post by **citrus3000psi** » Wed Jun 10, 2009 9:27 am

I have a palm emulator on an old laptop that I can use, I forget the software that it runs.

However I did what you just said already, I hooked up a light and read the ecu diag codes sucessfully. I just wondered why I couldn't get the CEL light to turn on, even on initial power and ignition.

jeffball610 · Post by **jeffball610** » Wed Jun 10, 2009 8:15 pm

MMCD is the software.

http://mmcdlogger.sourceforge.net/

There may be an issue with the wiring that may cause the CEL not to come on. I once had a bad ground in the instrument cluster of my 97 Eclipse and half the lights came on for no reason. Check your connections there. You might also trace the specific pin on the instrument cluster where it plugs into the dash and see if you can get something from the wiring itself. If you get a signal from the wiring, then it's the cluster. If you don't get a signal from the pinout in the wiring, trace it back to the ECU and see where it's bad.