Do You Have a Nagging TCC Shudder?
With the transmission and torque con-
verter on the bench, Devon inspected
the torque converter for signs of over-
heating; there were none. The torque
converter looked okay, but the trans-
mission fluid had a weird, slimy feel
to it.
With no signs of a torque converter
problem, he knew it was time to call the
ATRA Technical HotLine for help.
The Call to ATRA
Devon spoke with ATRA’s lead
technical advisor, Randall Schroeder.
Randall explained that, with the TCC
duty cycle at around 50%, the TCC
desired slip should have been modulat-
ing between 40-80 RPM and the TCC
actual slip should have been within
10% of that. In this case, TCC actual
slip was erratic and excessive.
Randall went over possible causes Figure 2: To check for fluid contamination, Devon took a sample of the transmission fluid,
for the TCC shudder, including prob- placed it in a metal container, and heated it on a hotplate
lems with the computer control, TCC
solenoid, TCC apply circuit, stator,
torque converter, and even fluid con-
tamination.
As soon as Randall mentioned
fluid contamination, Devon mentioned
the “weird, slimy feel” he’d noticed.
Randall then explained the many prob-
lems Chrysler had with moisture enter-
ing the transmission system, possibly
from the cooler or an external source.
Fluid Contamination
Confirmed
To check for fluid contamination,
Devon took a sample of the transmis-
sion fluid, placed it in a metal container,
and heated it on a hotplate (figure 2).
As the fluid heated up, he could see
small air bubbles forming and steam
coming from the surface of the trans-
mission fluid, which confirmed the
presence of water.
From there the search was on to
locate the source of the contamination.
Figure 3: After confirming that the Jeep he was working on wasn’t covered under Chrysler’s
Devon knew he had to inspect the
recall, Devon replaced the dipstick tube seal (part # 05189087AA
transmission cooling system and radia-
tor. He traced the transmission cooler The cooling condenser was a com- But the A/C system appeared to be
lines to the front of the vehicle, where bination A/C condenser and transmis- operating normally and was blowing
he found that the transmission cooler sion fluid cooler. With the transmis- ice cold, so he concluded that the A/C
lines didn’t go to the radiator: These sion cooling system sharing the same system wasn’t leaking, or the A/C sys-
cooler lines went past the radiator and condenser as the A/C system, there was tem would have been low on refrigerant
were attached to a cooling condenser in a possibility that the A/C system was and been blowing warm.
front of the radiator. leaking into the transmission side of the With the transmission cooler out of
combination condenser and contami- the picture, the only remaining source
nating the transmission fluid. for water contamination was external.
10 GEARS March 2010
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