B&M 70248 CONVERTER LOCKUP CNTRL - Manual (Page 4)

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be necessary to remove the oil pan
and identify which kind of solenoid
and wiring scheme is used on your
particular unit. A prewired four pin
transmission connector (attached to
the Converter Lock-Up Control mod-
ule) is provided for these applications.
LOCK-UP CLUTCH AND
SOLENOID BASICS
The lock-up clutch is located inside
the torque converter and is designed
to eliminate torque converter slip for
improved efficiency. In GM vehicle’s
the speed at which lock-up clutch en-
gagement occurs is controlled either
by hydraulic circuits inside the trans-
mission or by the vehicles Electronic
Control Unit (ECU). Lock-up clutch
engagement occurs when the Con-
verter Clutch Apply Valve changes
position and vents the area behind the
lock-up clutch piston. The converter
clutch apply valve’s position (on/off) is
determined by the converter clutch
solenoid and the availability of control
pressure. In most early applications
the solenoid is always energized and
control pressure is supplied by a shift
valve in the valve body which deter-
mined at what speed lock-up occurred.
Later applications eliminated the shift
valve altogether and supply control
pressure continuously. In the later units
the ECU is used to energize the sole-
noid at the appropriate speed by pro-
viding an external ground to the sole-
noid. In all of the above cases control
pressure becomes available only af-
ter the transmission shifts out of first
gear. Hence the torque converter
clutch will never lock-up in first gear.
The converter clutch solenoid is lo-
cated inside the transmission, as are
the converter clutch apply valve and, if
equipped, Converter Clutch Shift
Valve. Access to these components
requires oil pan removal. Some appli-
cations may require inspection or
modification of these components.
The lock-up solenoid is connected to
a four pin connector located on the
transmission case. The pins on these
connectors are identified by the letters
A, B, C and D.
Lock-up solenoids come with either
one or two wires. The one wire style is
internally grounded and requires only
a +12V connection to energize. One
wire solenoids are generally hooked
up to connector pin A, see Figure 5.
Two wire solenoids require both +12V
and ground connections to operate.
Two wire solenoids are usually hooked
up to pins A and D, where A is +12V
and D is ground, see Figure 4. De-
pending on the application one or both
of the solenoid wires may also be
connected to pressure switches on
the valve body either before, or in-
stead of, going to pin D. Reversing the
polarity on a two wire solenoid can
damage an internal diode which pro-
tects the electrical system from volt-
age spikes.
TOOLS
Besides normal electrical repair tools,
i.e. wire cutters, stripper and terminal
crimper, a VOM (Volt Ohm Meter, or a
12V test light) is required to check
voltage polarity and circuit continuity.
Incorrect polarity connections or short
circuits will damage the Converter
Lock-Up Control electronic module
and void the warranty.
Transmission
electrical connector
pin identification
ECU
TCC sole-
noid
4th gear switch
Transmission
TCC applies in
2nd, 3rd or 4th
gear under ECU
control
TH-200-4R
TH-700-R4
4th gear pulse
switch
TCC & brake
switch
A A
D D
B B
Transmission
TCC solenoid
TCC & brake
switch
+12 V
Figure 5
Figure 4
Note: The above illustrations for
reference only. Your particular unit
may not have all components shown.
Figure 6
B
D A