Specifications
AUTOMATIC TRANSMISSION -
Troubleshooting
23-25
Code No. 51 Abnormal communication with engine-ECU
<Vehicles without TCL>
Abnormal communication with TCL-ECU
<Vehicles with TCL>
Probable cause
If normal communication is not possible for a continuous period of 1 second or more
when the ignition switch is at the ON position, the battery voltage is 10 V o r more
and the engine speed is 450 r/min or more, diagnosis code No. 51 is output. Diagnosis
code No. 51 is also output if the data being received is abnormal for a continuous
period of 4 seconds under the same conditions.
D Malfunction of connector
D Malfunction of the engine-ECU <Vehicles without TCL>
D Malfunction of the TCL-ECU <Vehicles with TCL>
D Malfunction of the A/T-ECU
Replace the A/T-ECU.
NG
Check the trouble symptoms.
NG
Replace the engine-ECU.
<Vehicles without TCL>
Replace the TCL-ECU.
<Vehicles with TCL>
OK
Check the trouble symptoms.
OK
Harness check
D Between engine-ECU and A/T-ECU
<Vehicles without TCL>
D Between TCL-ECU and A/T-ECU
<Vehicles with TCL>
NG
Repair
Check the following connectors:
D C-30, C-34, C-38
<4G6-vehicles without TCL>
D C-30, C-37
<6A1-vehicles without TCL>
D C-10, C-30, C-51
<Vehicles with TCL>
NG
Repair
Code No. 54 A/T control relay system Probable cause
If the A/T control relay voltage is less than 7 V after the ignition switch has been
turned ON, it is judged that there is an open circuit or a short-circuit in the A/T control
relay earth and diagnosis code No. 54 is output.
Then the transmission is locked into 3rd gear as a fail-safe measure, and the N
range lamp flashes at a frequency of 1 Hz.
D Malfunction of the A/T control relay
D Malfunction of connector
D Malfunction of the A/T-ECU
Check the A/T control relay. (Refer to P.23-53.)
NG
Replace
OK
Check the following connectors:
B-30, C-28, C-30, C-41, C-45
NG
Repair
OK
Harness check
D Between control relay and body earth
D Between control relay and battery
D Between control relay a nd A/T-ECU
NG
Repair
OK
Check the trouble symptoms.
NG
Replace the A/T-ECU.