The D4 light

I seem to have a D4 light which sometimes is on (solid) and other
times is not on. At first I thought the LED was failing but then in
the service literature it appears that D4 is used as a TCU diagnostic
readout. Do you think the TCU is trying to tell me something? From
online reading it seems that the "S" light would be lit in the case a
code was stored...

The transmission works fine, under load sometimes it upshifts at
higher RPM than it should, and when shifting under load it flares
(this is most obvious on 4-3 downshift), but it never slips out of
gear or fails to go into gear.

" > wrote in
ups.com:

> I seem to have a D4 light which sometimes is on (solid) and other
> times is not on. At first I thought the LED was failing but then in
> the service literature it appears that D4 is used as a TCU diagnostic
> readout. Do you think the TCU is trying to tell me something? From
> online reading it seems that the "S" light would be lit in the case a
> code was stored...
>
> The transmission works fine, under load sometimes it upshifts at
> higher RPM than it should, and when shifting under load it flares
> (this is most obvious on 4-3 downshift), but it never slips out of
> gear or fails to go into gear.
>
>


Year? Model? Engine? Mileage?

--
Tegger

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/

On Mar 5, 9:48 am, Tegger > wrote:
> " > wrote roups.com:
>
> > I seem to have a D4 light which sometimes is on (solid) and other
> > times is not on. At first I thought the LED was failing but then in
> > the service literature it appears that D4 is used as a TCU diagnostic
> > readout. Do you think the TCU is trying to tell me something? From
> > online reading it seems that the "S" light would be lit in the case a
> > code was stored...
>
> > The transmission works fine, under load sometimes it upshifts at
> > higher RPM than it should, and when shifting under load it flares
> > (this is most obvious on 4-3 downshift), but it never slips out of
> > gear or fails to go into gear.
>
> Year? Model? Engine? Mileage?

I'm sorry, it's a 90 Accord EX, 2.2 SOHC, 200k.

wrote:
> On Mar 5, 9:48 am, Tegger > wrote:
>> " > wrote roups.com:
>>
>>> I seem to have a D4 light which sometimes is on (solid) and other
>>> times is not on. At first I thought the LED was failing but then in
>>> the service literature it appears that D4 is used as a TCU diagnostic
>>> readout. Do you think the TCU is trying to tell me something? From
>>> online reading it seems that the "S" light would be lit in the case a
>>> code was stored...
>>> The transmission works fine, under load sometimes it upshifts at
>>> higher RPM than it should, and when shifting under load it flares
>>> (this is most obvious on 4-3 downshift), but it never slips out of
>>> gear or fails to go into gear.
>> Year? Model? Engine? Mileage?
>
> I'm sorry, it's a 90 Accord EX, 2.2 SOHC, 200k.
>
=======================================

How many times have you changed the tranny fluid, and was the correct
Honda fluid used?

'Curly'

On Mar 5, 10:46 am, motsco_ > wrote:
>
> How many times have you changed the tranny fluid, and was the correct
> Honda fluid used?

The fluid is old. The tranny needs to be flushed. The car sat for a
long time and the motor was repaired. I put a bottle of Lucas in it
after the motor repair to get it by.

I am not that concerned about the rough shifting in and of itself. I
am more curious about what would the D4 light being solid on some of
the time (i.e. normal), and sometimes completely off. Seems like it
should be flashing if there's actually trouble, or the S light would
be on. I tried "wiggling" the shifter but it doesn't seem to be
intermittent. The tranny behaves the same no matter what the state of
the light is.

Maybe it's just a flaky LED in the dash cluster?

" > wrote in
ps.com:

> On Mar 5, 9:48 am, Tegger > wrote:
>> " > wrote
>> roups.com:
>>
>> > I seem to have a D4 light which sometimes is on (solid) and other
>> > times is not on. At first I thought the LED was failing but then
>> > in the service literature it appears that D4 is used as a TCU
>> > diagnostic readout. Do you think the TCU is trying to tell me
>> > something? From online reading it seems that the "S" light would
>> > be lit in the case a code was stored...
>>
>> > The transmission works fine, under load sometimes it upshifts at
>> > higher RPM than it should, and when shifting under load it flares
>> > (this is most obvious on 4-3 downshift), but it never slips out of
>> > gear or fails to go into gear.
>>
>> Year? Model? Engine? Mileage?
>
> I'm sorry, it's a 90 Accord EX, 2.2 SOHC, 200k.
>



In your car the "S" light is used as a diag tool.

Your D4 light problem is likely a flaky connection somewhere, probably at
the shift lever. This *may* also account for the odd shifting behavior.
However...

You have 200K on the tranny, and old fluid. Failure to change the fluid
will cause irreparable damage to the clutches and hydraulics of any
automatic. In your case, Dexron-III is OK, but Honda ATF-Z1 is better.

I would have the fluid drained and refilled at least three times with Honda
ATF-Z1. If the transmisison isn't in too bad shape, this may be enough to
cure your flaring problem. If it does not, then you have severely worn
clutch packs, or sticking solenoids.

--
Tegger

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/

On Mar 5, 3:15 pm, Tegger > wrote:
>
> You have 200K on the tranny, and old fluid. Failure to change the fluid
> will cause irreparable damage to the clutches and hydraulics of any
> automatic. In your case, Dexron-III is OK, but Honda ATF-Z1 is better.
>
> I would have the fluid drained and refilled at least three times with Honda
> ATF-Z1. If the transmisison isn't in too bad shape, this may be enough to
> cure your flaring problem. If it does not, then you have severely worn
> clutch packs, or sticking solenoids.

Yeah, I plan to have it flushed via machine and obviously to use the
correct fluid. This question was more trying to figure out if I also
have a TCU gremlin to deal with... I'll check that harness at the
shifter next time I have that apart. I actually just had it apart to
lube the shifter rod and the park pin.

wrote:

> Yeah, I plan to have it flushed via machine and obviously to use the
> correct fluid.

DO NOT FLUSH IT!!!

Drain and refill with Honda fluid at least 3 times.

On Mon, 05 Mar 2007 18:01:28 -0800, wrote:

> On Mar 5, 3:15 pm, Tegger > wrote:
>>
>> You have 200K on the tranny, and old fluid. Failure to change the fluid
>> will cause irreparable damage to the clutches and hydraulics of any
>> automatic. In your case, Dexron-III is OK, but Honda ATF-Z1 is better.
>>
>> I would have the fluid drained and refilled at least three times with Honda
>> ATF-Z1. If the transmisison isn't in too bad shape, this may be enough to
>> cure your flaring problem. If it does not, then you have severely worn
>> clutch packs, or sticking solenoids.
>
> Yeah, I plan to have it flushed via machine and obviously to use the
> correct fluid. This question was more trying to figure out if I also
> have a TCU gremlin to deal with... I'll check that harness at the
> shifter next time I have that apart. I actually just had it apart to
> lube the shifter rod and the park pin.

NONONONO Noooooo. Do NOT have it flushed. Have it drained and filled, 3
times, with about a week between each time.

On Mar 5, 8:46 pm, Joe LaVigne > wrote:
>
> NONONONO Noooooo. Do NOT have it flushed. Have it drained and filled, 3
> times, with about a week between each time.

Interesting. The gospel I've always been handed is that a drain and
refill is the wrong thing to do. The explanation was that changing
the fluid would renewing the detergents, which slowly dislodges the
crud that is built up in the transmission, which then clogs the filter
and starves the pickup. (Which is the point of "transmission fix"
products, to bring back the viscosity of the fluid without adding new
detergent.) The flush, if done properly through the pickup instead of
the cooler lines and using fresh tranny fluid and not solvent, would
get rid of all the old fluid AND crud, to essentially reset the fluid
to a known state.

Maybe the hole in this, and why everyone is recommending repeated
short term fluid changes, is that the crud gets dislodged too slowly
for the flush to actually clean anything out, so it's really no
different than a one-time fluid change, which is a big mistake on a
neglected tranny.

It would be interesting to see what the factory repair manual
recommends, or maybe the 3-time change actually is what they
recommend, anyone know?