Mitsubishi MOTORS Space Runner 1999 Workshop Manual Supplement page 217

23-10
Code No. 51 Abnormal communication with engine-ECU
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 or 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.
<4G6-MPI>
Replace the engine-A/T-ECU.
<4G6-GDI>
MUT-II Self-Diag code
Is code No. 61 output by the engine-ECU?
Check the following connectors: B-53, B-52, B-10
Harness check
D Between engine-ECU and A/T-ECU
Check the trouble symptoms.
Replace the engine-ECU.
Check the trouble symptoms.
Code No. 54 A/T control relay system
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 circuit 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.
Check the A/T control relay. (Refer to P.23-52.)*
Check the following connectors:
<4G6-MPI> A-12X, B-111, B-112
<4G6-GDI> A-12X, B-10, B-12
Harness check
D Between control relay and body earth
D Between control relay and fusible link
D Between control relay and engine-A/T-ECU or A/T-ECU
Check the trouble symptoms.
NOTE
*: Refer to '99 SPACE RUNNER/SPACE WAGON Workshop Manual (Pub. No. PWDE9803).
AUTOMATIC TRANSMISSION -
Yes
OK
OK
NG
OK
OK
OK
Troubleshooting
Probable cause
D Malfunction of connector
D Malfunction of the engine-ECU
D Malfunction of the engine-A/T-ECU <4G6-MPI>
D Malfunction of the A/T-ECU <4G6-GDI>
No
Replace the A/T-ECU.
NG
Repair
NG
Repair
NG
Replace the A/T-ECU.
Probable cause
D Malfunction of the A/T control relay
D Malfunction of connector
D Malfunction of the engine-A/T-ECU <4G6-MPI>
D Malfunction of the A/T-ECU <4G6-GDI>
NG
Replace
NG
Repair
NG
Repair
NG
Replace the engine-A/T-ECU or A/T-ECU.