Mazda MX-6 1998, Workshop Manual

Page: 759 / 1282

TROUBLESHOOTING [GF4A-EL]
DTC P0740 Torque converter clutch circuit m alfunction
DESCRIPTION
• Powertrain control module outputs torque converter clutch signal, but no torque converter clutch
obtained
POSSIBLE
CAUSE
• ATF level low • Control valve stuck
• Torque converter clutch position slippage • Torque converter clutch control solenoid valve
• Powertrain control module malfunction malfunction
• Line pressure low
STEP
INSPECTION ACTION
1 Are amount and condition (color) of ATF okay?
Check for ATF leakage at transaxle connection
and gasket
Color
© Transparent red: Normal
© Black: Defective part in powertrain
© Light red: W ater mixed in fluid
© Reddish brown: Deteriorated ATF
t r 0 5 -1 7B AUTOMATIC TRANSAXLE FLUID
(ATF) INSPECTION [GF4A-EL]
Yes Go to next step
No Adjust ATF amount or replace ATF if necessary, then go to
step 7
• If ATF color is 2, disassemble transaxle and repair or
replace any defective parts as necessary
• If ATF color is 3 or 4, replace ATF
2 Check line pressure in D range (O/D OFF SW
OFF)
• Is line pressure okay?
a? 0 5 -1 7B MECHANICAL SYSTEM TEST
[GF4A-EL], Line Pressure Test
Yes Go to next step
No Repair or replace any defective parts, then go to step 7
• ATF leakage in transaxle case, oil pump, control valve
3
Inspect operation of solenoid valve
• Disconnect negative battery cable
• Disconnect solenoid connector
• Is it operating okay?
irr 0 5 -1 7B SOLENOID VALVE INSPECTION
[GF4A-EL]
Yes Go to next step
No Replace torque converter clutch control solenoid valve,
then go to step 7
17 0 5 -1 7B SOLENOID VALVE
REMOVAL/INSTALLATION [GF4A-EL]
4 Check operation of each valve and inspect return
spring
• Is each valve operating okay and is return
spring okay?
Yes Go to next step
No Repair or replace control valve and replace return spring,
then go to step 7
5 Check difference between engine speed and
turbine speed during torque converter clutch
operation in fourth gear
• Connect NGS tester to data link connector
• Check difference between engine speed and
turbine speed during torque converter clutch
operation in fourth gear
Is there a difference between engine speed and
turbine speed?
17 0 1 -40B POWERTRAIN CONTROL
MODULE (PCM) INSPECTION [KL]
Yes Replace torque converter, then go to step 7
No Go to next step
6
After diagnostic trouble code has been cleared,
recheck if diagnostic trouble code is shown
tr 0 1 -0 1 B ENGINE ON-BOARD DIAGNOSIS
[KL]
Yes
Return to step 1
No
Problem is a temporary slip of clutch, and should be
investigated further, then go to next step
7
Erase diagnostic trouble code from memory. Can
code be output after performing “After Repair
Procedure”?
Yes Go to appropriate inspection procedure
No Finished
0 5 -0 1 B -1 3