A/T skipping 1st gear

Thanks, that's reassuring. One thing that still bugs me is why I smelled
that burn odor when I got home with my car. It must have come from
somewhere under the hood.

DB

 

Dragging brakes. Dripping oil on some hot engine part. Belt slipping. Belt
rubbing against something. Are the motor mounts intact?

Did it happen one time only? If it happens again note the conditions.
Temperature, humidity, travel on an inclined surface (which will shift the
engine on the mounts), heavy load, recent average speed.

 

It only happened that one time. However, the original problem reappeared
again last night despite the replaced shift control solenoid. The #4
gear indicator started flashing after a short stop at an ATM machine.
Luckily, this time I knew to try to switch into gear 2 to get the car
going without all that torque converter work to get some speed. The
problem seemed to have disappeared after a longer stop, just like the
first time. I wonder what it is with short stops that cause this
problem. It might be an indication of a more serious problem developing
and I would like to prevent it without spending another $300+ for the
wrong medicine. Any ideas?

DB

 

That car just wants some cash from the machine.

That's probably unnecessary. The transmission control computer limits you to
second and fourth gears only when in "limp home" mode.

It could be some heat build-up causing the problem.

Did the $300 result in the actual change of the shift control solenoid
assembly? Did you get the old part?

Let's assume that a new solenoid was actually installed. I recall that you
have the service manual. Can you read the transmission control unit error
codes without a service tool. At least on older models you just watch the
flashing lamp on the TCU itself. If so, what error code is flashing now?
Still an eight as before?

The TCU itself may be failing or it could be a problem in the wiring. A
short to battery voltage, an open circuit, a low resistance to ground or an
adjacent circuit will register in the TCU and store an error code. The TCU
does not differentiate among various conditions. If any anomaly pops up in
the shift control solenoid B circuit for instance, the TCU lamp flashes 8
times. Some oil leaks into the connector in the engine compartment and the
technician leaps to the conclusion that the solenoid must be changed. As Tom
and Ray will tell you, he had a boat payment due.

 

Maybe just my service technician.

Well, as I wrote before, when in city with speed limits 35 or under, I
like to drive with the AT gear in D3 position but in this case all I got
was the torque converter acting like a slipping MT clutch. It was
obviously not engaging the 1st gear. Same in D4 position. I was able to
start almost normally with the shift lever in D2 position.

I doubt it because I operated the car for only a few miles before the
incident and it was night time. Then I drove another couple miles to a
restaurant where I spent about an hour and after that the symptom was
gone and still is gone. So this issue seems to be transient. The only
common thing between the two similar episodes was the short stop.

Oh yes, I explicitly asked for it and could tell the Honda dealership's
technician installed a new one.

According to the Service Manual, reading the code requires a special
tool to read the code which I don't have. I'm assuming though that it
would be the same code again as all the symptoms were the same. That
also means that they made me pay for the solenoid needlessly and the
problem may be somewhere else.

I think you might be right here though I doubt the technician gets some
extra pay from the dealer employer for this. It's more likely that he
just chose the easy way out while at the same time pleasing his boss for
the extra billing he generated.
Though some of you guys have been singing the praises of authorized
Honda service shops, I've had nothing but expensive disappointments with
them. I think I should have gone to my independent mechanic as before,
but because he could not take on my car right away, I though I would
give another try to a Honda service shop. What an expensive mistake that
was! It reminds me the case of a former co-worker of mine with a Honda
Odyssey problem. The power door motor started behaving erratically and
the Honda shop diagnosed it as needing a new servo motor. That costed
him some $500 and for a while the problems disappeared. Then the same
problem came back even with the new servo. He took it back to the same
shop where another mechanic found the problem being some loose ground or
something like that. When my colleague remarked that perhaps that was
the problem before the motor was replaced, they just shrugged their
shoulder by saying that "not necessarily." I have a feeling that's the
treatment I would get if I took back my car to them now. I hope my car
will be OK till my upcoming scheduled maintenance with my independent
mechanic and then let him do his own checking.

DB

 

It sounds as though the transmission is getting erroneous signals from the
computer. That could be a problem in the wiring or, less likely, the
computer itself. I would pull the connectors off at the TCU and, using an
ohmmeter, check the wiring. The troubleshooting procedure is in the service
manual. Concentrate on measuring the solenoid resistance.

You'll probably see high resistance readings where you would expect to see
the low resistance reading of each solenoid. Then you disconnect the
solenoid connector at the transmission and take another set of readings. If
those resistances are correct, the problem is in the wiring between the
solenoid connector and the computer. If not, one or more solenoids are
defective. There are probably four solenoids to check, two shift control and
two lockup.

If you still have the old solenoids, measure their resistance. If they are
okay the resistance will be in the range of 12 to 24 ohms. If they measure
several hundred ohms or higher, they were truly bad.

I went so far as to connect LEDs to the solenoid lines of my TCU to verify
that the correct signals were coming out of the computer while I drove.

You might even invest in the tool to read the diagnostic codes.

 

I don't see how this could yield any results with a transient problem as
this seems to be. Right now all is well and who knows when the problem
manifests itself again. That would be the time to carry out the thing
you suggest but I may not be in a situation when I could do it.

This I can do now and will report back on it later.

Great idea.

Well, I don't think I will keep this car long enough to make it
worthwhile.

It just occurred to me: what if the problem is in the lock-up control
solenoid instead? Just what is the function of the lock-up control
solenoid?

DB

 

The condition may not be transient even while the indication _is_ transient.
You may be on either side of the threshold of a failure indication. I had
the same intermittent indications when my lockup solenoids were going bad.
They got worse with heat but the resistance readings of the failing coils
was always high. When they got hot the current draw changed enough for the
TCU to register a problem.

Last week my TCU was flashing a #8 code. I previously found a bad connection
at the TCU. At that time I opted not to dismantle the connector and risk
breaking a wire. I simply reseated the pin in the connector. The problem
disappeared. When it reappeared last week I pulled back the carpet, grabbed
the cable bundle and moved it around a bit. The flashing indicator on the
dash didn't reappear so I pulled the fuse to reset the TCU lamp and went
whistling past the graveyard.

I diagnosed the problem with an ohmmeter even though the dash indicator
wasn't always flashing.

Bad lockup solenoids or associated wiring lead to funky shifts and rpm
flares.

 

OK, I measured the resistance between the connectors of the old
solenoid: it was 30 ohms. I guess it's a bit too high, right?

Thanks for the tip. I'll see what I could do though I am a bit hesitant
to screw around with the TCU.

Good to know. At least when I experience those symptoms I will know
where to start looking.

Thanks again,
Dan

 

No, that's probably within limits. Apparently they replaced a good solenoid
assembly. Sorry. What is the accuracy of your ohmmeter? The range of
acceptable values for my old '88 Prelude transmission is 12 to 24 ohms. When
my solenoid went bad both coils measured about 900 ohms. Does your Accord
service manual give the tolerance? (It may be buried in the troubleshooting
chart.) At the low end of the range, your ohmmeter may be off. I wouldn't
worry about 30 ohms. I _would_ be concerned if it was 300 ohms.

The next question is, what are the resistance readings of the solenoids in
the vehicle?

The TCUs are solid. They have a lot of protection circuitry and they have to
withstand some wild temperature swings. The circuit board components are
encapsulated. You'll have a hard time killing it. The external wiring is the
weak link in the system.

 

I haven't calibrated it. I need to find a resistor with known value and
see.

It is also 12-24 ohms.

It's an old digital Micronta multi-meter I have mostly been using for
voltage measurement and for continuity checking. The Ohm meter part's
scale seems to be designed to measure kilo Ohms, so on the low end it
might not be very accurate.

That's kinda' hard to get to without lifting up the vehicle. So I don't
know if I can do that. The lock-up control solenoid would be a lot
easier as it is closer to the top.

That's sounds right though according to the troubleshooting charts a
faulty A/T gear position switch might also cause similar symptoms. I
guess this will have to be a process of elimination. Unfortunately, due
to the transient nature of the symptom, after every fix attempt I may
have to wait for weeks to know if the fix worked.

DB

 

On my car at least the transmission-side solenoid connectors are only
available by opening the hood. You can't get to them from below. The best
place to take the readings is at the transmission computer connector. In
that way you'll check the wiring from the TCU to the transmission too. If
you see a problem there, go for the connectors at the transmission. The
troubleshooting charts also direct you to check for the presence of voltage
on certain connectors. You can't check that in the engine compartment.
Everything is available at the connectors which plug into the TCU.

Speaking of that, you'd think that a professional technician would have
access to a service manual. Through ignorance or greed he bypassed the
testing procedure which would have told him that the solenoids he was about
to replace were not defective. That shop owes you several hundred dollars.

 

You're right. I checked the location of the connector under the hood and
it was much higher than the solenoid itself and it is accessible
relatively easy.

Yes, but depending on the the code reading there are different
troubleshooting procedures and I can't read the code. I was also
wondering if I could possibly reset and damage the TCM by not having the
right service tools.

I'm sure that I could have gotten a good technician to diagnose the
problem as it should have been because I'm sure they have those, too.
But then they also have marginal or lazy ones who make shortcuts when
they think they can get away with it. I probably got the latter. Each
job has some given labor hours allotted and if the mechanic is not good
he might not be able to finish it in that time. So they take the
shortcuts.

DB

 

Assume for the time being that it's an eight. As long as you're testing
things you can look at all solenoid resistances. Do you have a schematic of
the transmission control wiring? Do you have the authentic Honda manual?

Are you sure that the TCU itself does not have a lamp on it to show the
codes in addition to the service connector. You'll probably have to pull
back the carpet under the passenger's feet. If there is a little flap of
carpet there fastened with a Velcro strip that's probably for the engine
control computer. If the engine computer has a lamp, the TCU probably has
one too. If so, pull back the carpet. (You might have to remove a fastener
to release it.) If you see a plastic window on the side of the TCU, that's
the viewing port for the lamp. Turn the ignition on. It is not necessary to
start the engine. Any flashes of red light?

They're almost bullet-proof. To reset the computer after an error condition
has been corrected, you pull out a fuse for 10 seconds and replace it. It is
usually the 10 ampere alternator sense fuse in the engine compartment. On my
car it is marked "clock."