I was wondering if anyone had any advice for trying to figure out why my 1996 Honda Civic DX was stuck in limp mode. I had exposed wires hitting the throttle body causing the lights to dim and the the speedometer to operate sporadically. I taped the wires and replaced Fuse 15 because it was blown. I have taken it to Autozone and had no luck getting a code off of it, they kept getting a Link Error from the diagnostic unit and trying to get the code myself using a piece of wire didn't work either, it wouldn't blink at all. I am really hoping the ECU isn't broken and that there are a few other things I can try before having to replace it.

 

When you jumper the test plug, the spark timing should change dramatically, and go to the 10 degree BTDC mark on the pulley.

Start engine and drive if necessary until CEL comes on. Then put the test jumper in without turning the key off. If the ECU has no backup power, it will forget codes every time the ignition is turned off.

 

Check whether hood fuse 43 is blown. This fuse supplies power to the DLC connector where the code reader plugs in.

 

Ive checked fuse 43 and it isn't blown. Also I tried using a piece of wire on the test plug next to the ECU and got nothing, it didn't blink or clear the CEL. I've been looking up the symtoms of a bad ECU and from what I have read so far it will throw a trouble code 1 that says "malfunctioning ECU".

The only other piece of information I can think might be relevant is under the speedo where it says "Maintenance Required" the box under it is colored red.

 

I can take a video if that helps, i'm at a loss at this point.

 

It could be stuck in test mode, i.e. wire shorted or someone left a wire in the test plug and the plug you've been dealing with is not the real plug.

Unplug the first O2 sensor to make sure a code is thrown. If it's stuck in test mode the CEL will start blinking when you drive then.

 

Well I did have a fuse blown from having exposed wires under the throttle body, fuse 15 went and was causing the speedometer to act erratically and the lights were dimming. I will give this a shot in the morning. Oh and the the test plug I was putting the wire into was a blue plug above the ECU.

Thanks for the help so far, its critical I get this car running properly for work/college.. Any attempt I make instead of just staring at it definitely makes me feel better about it.

 

I pulled the O2 sensor, the CEL did not start blinking it just stayed in limp mode with the CEL still on. Also the thermostat ground was cleaned off (it was corroded), then pulled the ECU and checked for any melted solder and burn marks, shows no signs of either.

Unsure of what or where to check next.

 

http://youtu.be/Wa5Jbxj9VPw


Sorry, the video is sideways but its mostly so you can hear it when I attempt to rev it.