89' prelude not shifting properly

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M&D - 01 Jan 2006 15:28 GMT

I have an 89 prelude si with an automatic transmission that will not shift
into third.....while it is cold it won't shift past second gear,...after it
warms it shifts directly into fourth from second....will it require a
teardown to fix?...

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High Tech Misfit - 03 Jan 2006 00:45 GMT

> I have an 89 prelude si with an automatic transmission that will not shift
> into third.....while it is cold it won't shift past second gear,...after it
> warms it shifts directly into fourth from second....will it require a
> teardown to fix?...

I'm not sure about that version of Prelude, but on some 4th-gen Accords
(1990-93), those are symptoms of a failing tranny control unit (TCU). The
tranny itself is usually OK.

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M&D - 05 Jan 2006 05:57 GMT

Thanks....I'll price one...Is it inside the transmission ?.

> > I have an 89 prelude si with an automatic transmission that will not shift
> > into third.....while it is cold it won't shift past second gear,...after it
[quoted text clipped - 4 lines]
> (1990-93), those are symptoms of a failing tranny control unit (TCU). The
> tranny itself is usually OK.

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Michael Pardee - 06 Jan 2006 04:28 GMT

> Thanks....I'll price one...Is it inside the transmission ?.

No, the transmission control unit is similar to the ECU and is normally
mounted in the passenger compartment. Dunno exactly where in the Prelude,
though. Wrecking yards are often good sources of ECUs and TCUs. A good price
is on the low side of $100 US, with a 30 day warranty... enough to determine
whether it is working right. If it makes it for 30 days it should last the
life of the car.

I agree it sounds more like the TCU than the tranny - it's just doing what
the TCU tells it to do.

Mike

>> > I have an 89 prelude si with an automatic transmission that will not
> shift
[quoted text clipped - 8 lines]
>> The
>> tranny itself is usually OK.

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Charles - 07 Jan 2006 03:01 GMT

> No, the transmission control unit is similar to the ECU and is normally
> mounted in the passenger compartment. Dunno exactly where in the Prelude...

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
itself).

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.

--
Chuck

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