Where is the obd2 plug on a 1990 dodge 4G work van

There is none on that year but you can retreive codes by using your key, within five seconds turn ignition on/off,on/off on,leaving on watch check engine or limit light it will flash codes, example-if light flashes once then pauses then flashes twice this is code twelve,when done displaying it will flash five then pause then five again this is code 55 meaning no further codes, Hope this helps

Should be under the steering wheel /dash. But I'm not sure if there is one. They didn't have OBDII till 96

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