if it is the 4.6 V8 - it is located under the glove box on the passenger side. The plug-in code reader will work & tell you what is wrong. Took mine to Auto Zone - they did it or free but I had to tell the dude where it was, as he was walking toward the drivers side.
There is a CEL, Check Engine Light, on the 1989 Thunderbird.
Take it to repair.
You have it checked for codes and diagnose the cause of the code.
The process of elimination works. If you have a check engine light, start there.
After the Explorer is scanned for trouble codes to diagnose and then repair the malfunction , then the check engine light can be reset
Pretty simple connect an obd2 scanner and it will pull the error codes for the check engine light then look up the error code and diagnose and fix your problem
There are pages and pages of things that will turn the check engine light on. You need to have it checked for codes, and can diagnose from there.
That is the check engine light. It means that the engine computer has detected a malfunction. You need to have it checked for codes. You can then diagnose.
If your check engine light is blinking with the engine running that is indicating a misfire - get your vehicle scanned for any trouble codes to diagnose and then repair the problem
Have vehicle scanned to determine the problem
for the check engine light go to autozone and they will diagnose your engine for free as for the speedometer you will proobably have to replace the speed sensor
Then you need to have code checked, you can diagnose from there.