Mitsubishi MOTORS Space Runner 1999 Workshop Manual Supplement page 496

Code No. 31 Detonation sensor system
Range of Check
Ignition switch: ON
Excluding 60 seconds after the ignition switch is turned to ON or immediately
after the engine starts.
Engine speed is approx. 5,000 r/min or more
Set conditions
The change in the detonation sensor output voltage (detonation sensor peak voltage
at each 1/2 revolution of the crankshaft) is less than 0.06 V for 200 times in succession.
Measure at the detonation sensor con-
nector A-50.
Disconnect the connector and
measure at the harness side.
Continuity between 2 and earth
OK: Continuity
NG
Check the harness wire between the
detonation sensor and earth, and repair
if necessary.
MPI –
Troubleshooting
OK
Check the following connectors:
A-50, B-31
Check trouble symptom.
Check the harness wire between the
engine-ECU and the detonation sensor
connector.
Repair
Probable cause
Malfunction of the detonation sensor
Improper connector
short-circuited harness wire of the detonation sensor
circuit
Malfunction of the engine-ECU
NG
OK
NG
OK
NG
13B-15
contact, open circuit
Repair
Replace the detonation sensor.
Check trouble symptom.
NG
Replace the engine-ECU.
or