ODBII Error - "P0743 Torque Converter Clutch Circuit Electrical"

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Don-Don - 24 Dec 2004 04:06 GMT

I am getting an ODBII Error - "P0743 Torque Converter Clutch Circuit
Electrical" on my 1998 Ford Explorer XLT AWD. The "O/D Off" light
flashes in the dash as well as the Check Engine light. I have a code
reader and it gives the message above. I have tried to read up on
what the error might be, but there is limited information. Many
people say that they have had $1200-$3000 transmission jobs to get it
fixed, while others say to unhook the battery for 15 minutes to clear
the codes and keep on going. Others have stated that this code is not
critical to the life of the transmission. I have had the problem for
about two weeks now and the light comes on and the transmission has
problems (not major) shifting when accelerating from 1st or 2nd into
the next higher gear (2nd or 3rd respectively). Then it has a problem
downshifting into first when coming to a stop - kinda a "ka-thunk"
noise. If I use the code checker to clear the codes the transmission
shifts perfectly. then after a random amount of time (2 minutes to 2
hours) of driving, the lights come back on. If clearing the codes
makes everything shift properly, what could it be? I have read a
few other websites that talk about a "transmission solonoid for
coupling and un-coupling of the torque converter". Anyone know what
this really means and is it something that can be changed by an above
average home-mechanic. I have worked a lot with antique cars and many
other things, - just not with AWD transmissions. Thanks for any
information.

Happy Holidays!

Don C.

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Jim Warman - 24 Dec 2004 06:25 GMT

I'm assuming you have the 5R55E transmission.... Depending on the failure,
P0743 "may" be benign and simply cost you extra at the pumps..... or it
could have the TCC not releasing when it needs to - continued driving may be
just getting the thing closer to catastrophic failure and a bigger hit to
the wallet (let alone the inconvenience and extra cost of any "unscheduled"
breakdown - perhaps coming at a time when one can least afford the finacial
aspect or when one is running very late for something very important).

When the lamps illuminate, the TCM will go into a preprogrammed failure
strategy... hence the rough feel when the lights are lit, smoothing out when
you clear the codes. Continuing to clear the codes and drive may be the
automotive equivalent of watching that big, leaking goober on an important
body part get bigger without consulting a physician. These things never,
ever "heal themselves" and usually only get worse with the passage of time
and miles.....

In case you're wondering.... this code indicates that the PCM has not seen a
voltage drop across the TCC solenoid (search "voltage divider circuits" for
an understanding of the logic)..... This could indicate either an open in
the wiring, an open in the solenoid or an intermittent short to ground in
the solenoid control circuit.

>I am getting an ODBII Error - "P0743 Torque Converter Clutch Circuit
> Electrical" on my 1998 Ford Explorer XLT AWD. The "O/D Off" light
[quoted text clipped - 23 lines]
>
> Don C.

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Don-Don - 29 Dec 2004 05:53 GMT

Great information. I am going to do a few searches tomorrow on the
Voltage Divider Circuits. It sounds like from what you say that the
problem "could" be a poor connection somewhere. Wouldn't that be
nice. I only wish it was warmer weather her in the DC area and I
would take a longer look at it. Do you (or anyone) have any short
cuts to where the wiring connections might be. I don't know if the
wiring would be down under the vehicle near the transmission or near
one of the transfer cases - that would be a big help to start.

>I'm assuming you have the 5R55E transmission.... Depending on the failure,
>P0743 "may" be benign and simply cost you extra at the pumps..... or it
[quoted text clipped - 45 lines]
>>
>> Don C.

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