On my '88 Prelude the TCU is under the carpet about where the passenger's left
toes would be. You might even notice a little flap of carpet there kept in
place by a strip of Velcro. You can peel that back and have a look at the
light-emitting diode which flashes if the module detects an error. Watch the
lamp while turning the ignition to the On position. Count the flashes. Any
number greater than zero means the TCU has detected a problem (external to
If your S3 indicator on the dash is not flashing (and I'm sure you would have
mentioned it), you might still have a failure indication stored in the computer.
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