Hi I purchased a code reader for my 1991 Ford Explorer XLT and I can't seem to find the plug in to do the test. Can someone give me a detailed description and/or a diagram that will show me where it is. Thanks

Most scanners and code readers only work on 1996 or later vehicles. Prior to 1996, Service Check Connectors, located under the dash, had to be jumped with a paper clip and Check Engine Light flashes counted.