A/T skipping 1st gear

"Charles" > wrote:
> No, that's probably within limits. Apparently they replaced a good
> solenoid
> assembly. Sorry. What is the accuracy of your ohmmeter?

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

> 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.)

It is also 12-24 ohms.

> 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.

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.

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

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.

> 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.

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

Dabbler wrote:
>> The next question is, what are the resistance readings of the
>> solenoids in the vehicle?
> 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.

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.

> ...according to the troubleshooting charts...

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.

--
Chuck

"Charles" > wrote:
> 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.

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.

> 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.

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.

>> ...according to the troubleshooting charts...
>
> 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.

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

Dabbler wrote:
> Yes, but depending on the the code reading there are different
> troubleshooting procedures and I can't read the code.

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?

> I was also
> wondering if I could possibly reset and damage the TCM by not having
> the right service tools.

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."

--
Chuck