Can't get CEL code


#1

My 92 Accord’s CEL comes on seemingly as soon as it is fully warmed up. The thing is, I can’t get the code for some reason. I pulled the two wire connector out and shorted it with a few different things, but I get no blinks from the CEL. I’ve tried it with the CEL already on, and after turning the car off. It’s not telling me anything. Anyone know why I wouldn’t be getting a code? Thanks!


#2

a paper clip straightened out into a U shape works. just make sure the paper clip is not plastic coated.

key on run, but engine off, with the wire in the connector should give you the blink.


#3

The two-terminal diagnostic (or, “service”) connector is located under the right corner of the dash. Connect the two wires with a jumper wire (paper clip, etc.).
The green/white wire goes to ground through the ECU (engine computer) terminals D21 (now, a blue/white wire), and ECU terminal D22. Use a digital multimeter to check for ground (zero ohms) of the green white wire. The ECU may not make this ground complete until it’s powered. I don’t know.

The orange/red wire, from terminal D4 on the ECU (or, “PCM”), carries the CEL (Check Engine Light) code. Using the digital multimeter, touch the positive probe tip to the orange/red terminal, and the negative probe to a ground (screw, etc.). With the meter set on volts, and the ignition key ON, the meter should show voltage pulses. If not, the signal is probably not coming from the ECU.

Disconnect the electrical connector(s) from the ECU. Use the multimeter to check for continuity (zero ohms) of the green/white wire from the service connector to terminal D21 and D22. Check the orange/red wire for continuity from the service connector to D4 on the ECU.

If you can’t find a wire fault, or, get a trouble code, you’ll need to test each sensor, and other components, individually.

If you’re not using the repair manual, you’re not helping yourself.


#4

You need to turn the car all the way off, then put the key in the “run” position but don’t start it. And you don’t need to bother warming it up-- the code will be stored.