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> The "check engine" light is on. The mechanic who adjusted stuff so the
> car passed it's Florida emission test with flying colors disconnected
> the battery, and it stayed out for a day or so. I bought the Haynes
> Computer Diagnostic book and discovered the little test box on the
> left side of the fender area just ahead of the firewall, opened it and
> stuck the test probe into hole #2 as directed. Then I pressed the test
> button for more than one second and less than three and waited for the
> light to flash. After ten minutes, I concluded that it wasn't going to.
> I pushed the button for five seconds to clear any fault code. The
> Check Engine light remained firmly committed to the 'on' condition.
> I plugged the test prod into hole #6, which is supposed to check
> ignition. I pressed the button for a second, and in moments the light
> delivered 1 - 1 - 1, the signal for 'all's well'. After concluding the
> test as instructed by Haynes, the Check Engine light remained on.
> Anybody know why I don't get ANY code from the test with the prod in
> hole #2?
Your LH 2.4 fuel injection computer (aka ECU) seems to have got itself thoroughly confused. Probably either because of bad inputs or an internal failure. The good news is that the car runs and a battery disconnect seems to reset the computer, so it is still mostly alive. The bad news is that the '89 LH systems have a track record for losing their minds.
In injection system test mode (#2 terminal), were you seeing the LED light at all when you pushed the button? If the ECU is not responding at all to diagnostic socket #2 then it could be a wiring problem at the socket or between it and the computer. However, because ignition diagnostic mode (#6) works, I wouldn't get too hopeful.
Also check #2 function in darkness, is the LED glowing faintly? If so then that would seem to indicate faulty circuitry inside the ECU.
Immediately after doing a battery reset to put the Check Engine light out, does the LED now light and the diagnostic socket now function properly on #2? Does the Check Engine light come back on just a few minutes after starting? If so then you may have a problem with the O2 sensor and it is somehow managing to hang the diagnostic chip in the ECU. You could test the voltage at the O2 sensor test point to see if it is within spec.
Formal diagnosis would require a basic check of all injection/ignition components and verifying that the proper signals are present at the ECU connector plug. If the book tells you what to look for then great, do it -you'll learn a lot about your engine. However, the most expedient approach is to switch in a known good ECU (matching number) if you have access to one.
Be sure to take a sedative before asking the price of a replacement ECU.
-Dave
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