AUTOMATIC TRANSMISSION ± Troubleshooting <A/T>
23-20
INSPECTION PROCEDURE 6
Downshifting does not occur
Probable cause
Downshifting does not occur under conditions when downshifting should occur. Check
shifting from 2→1, 3→2 and 4→3 respectively.
D Malfunction of solenoid No. 1, No. 2
D Malfunction of A/T-ECU
D Malfunction of power train internal parts
L: Refer to the Transmission Workshop Manual.
Is a normal diagnosis code output?
No
To Inspection Chart For Diagnosis
Code (Refer to P. 23-9.)
Yes
Does not the A/T shift from 4→3?
No
Which gear is engaged when the A/T
is shifted from D range to 2 range
(accelerator OFF) while in 3rd gear?
(DRIVE 1ST)
Malfunction of solenoid valve No.
2 L
Yes
(DRIVE 2ND, 4TH)
Malfunction of 3-4 shift valve L
Does not the A/T shift from 3→2?
No
Does the vehicle move in 1st gear in
D range?
(DRIVE 4TH)
Malfunction of 2±3 shift valve L
Yes
(DRIVE 1ST)
Malfunction of solenoid valve No. 1 L
A/T does not shift from 2→1. Does the A/T shift from 3→4 in D range?
No
Malfunction of solenoid valve No.
2 L
Yes
Does the vehicle move forward in L
range?
No
Malfunction of 1±2 shift valve L
Yes
Does the vehicle reverse in R range?
No
Check the brake No. 1. L
Yes
Check the brake No. 2. L
Check the trouble symptoms.
NG
Replace the A/T-ECU.
INSPECTION PROCEDURE 7
Shifting point abnormality
Probable cause
Shifting occurs at points which are different from the shift pattern. Note that the
shift pattern will vary in different modes and at high A/T fluid temperatures.
D Malfunction of A/T fluid temperature sensor
D Malfunction of A/T-ECU
Is a normal diagnosis code output?
No
To Inspection Chart For Diagnosis
Code (Refer to P. 23-9.)
Yes
MUT-II SERVICE DATA
D 15 ± A/T fluid temperature sensor
OK: 70 ± 90_C after engine
warmed-up
NG
Code No. 15, 16 ± A/T fluid temperature
sensor system (Refer to P. 23-10.)
OK
Replace the A/T-ECU.
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