Recently I finished my obd 2a b18b1 swap into my 1998 ek (using jumper harness to convert to obd1) and now am stuck with a check engine light I am unable to fix. I'm not 100% sure if my swap caused this CEL since the previous owner had removed the bulb, but my car runs fine and doesn't have any of the major issues people with a code 0 seem to have (car won't start or they are in some sort of limp mode). I have read pretty much every code 0 thread on honda-tech now but haven't been able to find a solution . Most of the fixes people seem to come across are a bad ECU, poor thermostat ground, main relay, some short in the wires, etc.

One of my friends suggested it could be due to the SiR cluster swap that was done but I couldnt find any more info on that. If anyone has any tips it would be much appreciated

Thanks

 

With the test jumper out--
CEL should come on then go out when you turn the key on but don't crank.
CEL should stay off while running unless there is a currently active code-- then it is on steady.
With the test jumper in--
CEL should come on and stay on steady when you turn key on or start the engine, if there are no codes.
Or, CEL should blink out codes if there are codes.

If the memory back up circuit is not working (BACK UP fuse under the hood feeding constant power to the ECU on the white and blue wire), the ECU will not remember codes with the key off. If the CEL comes on while running, indicating a code, you can check by putting the test jumper in without turning the key off.

 

With the test jumper out my CEL turns on and stays on when the key is turned and while the vehicle is running (even after resetting the ECU).

When I jump the service connector, the CEL brightens and stays steady which indicates a code 0 (from what I've read).

I'm fairly certain the memory back up circuit is functioning because the ECU seems to store this "code 0"

 

What ecu?

 

Obd1 p75

 

Start by testing whether fuse 44 or 13 is blown. Test with a multimeter. Visual inspection is unreliable.

 

Just checked those, both are still in good condition and are working

 

Does 44 get constant voltage?

Does 13 get voltage with key in ON(II)?

 

Try another ECU.

 

locate obd1 p75 or an obd2a p75

 

Haha...just read first post and found that the car starts and runs fine.

1) Use a multimeter to check for a short to ground in the CEL wire that runs between the cluster and ECU.

2) Use a multimeter to check for a short to ground in the Brn wire that runs from the service connector to the ECU.

 

I confirmed there was no short between the cluster and ECU.

This was the brown wire I checked (plugged into a brand new obd2a to obd1 yonaka jumper harness).

I believe this wire may be shorted as I was only getting a reading of around 0.01 ohms. Would it be the culprit? When I tested the resistance between the black and brown service connector wires there was no short.

Just a little confused since if that brown wire going to the ECU was shorted, shouldn't I be getting the same reading from putting my probes in the service connector?

 

The Brn wire has a short to ground. One possibility is that the Blk wire lacks proper continuity to body ground. Check that now.

 

Sorry for the delay, been pretty busy with work and havent had time to do some more diagnosis. Anyways, I just confirmed that the black wire is a good ground. Where would I begin when trying to fix the short in the brown wire?

Also, wouldn't the cel always be bright instead of dim since the scs connector is basically being always "jumped" (due to the accidental short)

 

Have you ever mentioned this^ in your thread? Please provide more details.

 

Earlier I described how I have been attempting to pull CEL codes and why I believe it is a code 0.

I was just confused since we pull codes by shorting the service connector but it sounds like my brown wire has been (and still is) shorted

 

Oh, okay. The wire running between the CEL bulb and ECU is clearly bad. Run a new wire to bring back your smile.

 

Just ran a new wire from the cluster to ecu (green/orange stripe), unfortunately the cel persists