QuestionHi. We recently put a $700.00 "junk yard" transmission in our 98 Voyager. That same day, the "check engine soon" light came on. Took it to Lithia, and cause: FOUND CODES P0740 (TORQUE CONVERTER CLUTCH CIRCUIT) AND P01281 (ENGINE COLD TOO LONG) NEEDS TORQUE CONVERTER. NEEDS THERMOSTAT. We replaced the thermostat, hoping that would fix the problem. On the way home, "Check Engine Soon" light came on again. Do we need to replace the torque converter? We are trying to make this van "sellable" and have already put $1385.00 into it. Any advice?
AnswerHi Stephanie,
The trouble shoot for this code points to the following steps before concluding the need to replace the torque converter clutch (not necessarily the entire torque converter but just that part, which I believe nonetheless requires removal of the trans):
fluid level OK?
electrical connectors?
do shift lever test
verify flash level of trans controller for need to upgrade the software
check for technical service bulletins that might apply
drive the van and see if the torque converter clutch will engage (you should note the rpm drops about 5% when you pass through the speed of about 40-50 mph)
if it does, then try wiggling the wires and check for shorted circuits.
if the clutch doesn't come into play then do a hydraulic pressure test on the trans
on the basis of that test decide what needs to be done.
I might mention that the lack of a torque converter lock up capability just means that you would lose about 5% in the mpg figure on the highway as compared to if it worked. There are many vehicles than don't have this feature. So if you can convince a potenetial buyer that this malfunction will not meaningfully affect the function of the transmission just the marginal affect on fuel economy it is probably not going to be a repair that is worth it to you or to the buyer(you can negotiate the discount for it). It can be repaired later when the trans suffers an inability to shift properly or even to drive the van which commonly requires a total rebuild. The clutch for the torque converter is purely for gas economy. You might want to get a free readout of the fault code again at an Autozone Parts store or pay for one from a shop for maybe $40 and have that to show to a prospective buyer. If you don't have a smog inspection program which may refuse to pass a vehicle that shows any fault code whatsoever, then the buyer would be "home free" as it were. A good running van with a minor fault affecting only economy to a minor extent.
One other remedy might be to replace all the transfluid with Mobil Synthetic trans fluid (10 qts at $4/qt plus cost of a complete system flushout using a special pump to exhange the entire contents of the trans and converter). Not all trans shops can do this so find one that has that tool and will use the Mobil synthetic. These transmissions are sensitive to the type of fluid used and I have gotten feadback that a trans that had problems with shifting was significantly improved with the synthetic. Ask the shop if they think it would possibly correct the problem with the torque converter clutch and if not, then forgo this attempt.
Roland
