Mazda MX-6 1998, Workshop Manual

Page: 51 / 1282

TROUBLESHOOTING [ENGINE CONTROL FS]
KOEO, KOER P0113
DTC P0118
IAT sensor circuit high input
ECT sensor circuit high input
DESCRIPTION
• DTC P0118 (ECT) or P0113 (IAT) indicate corresponding sensor signal is greater than
self-test maximum. Maximum for ECT and IAT sensor is 4.6 volt or -5 0 °C {-4 6 °F}
[Possible Cause]
• Open in harness (IAT or ECT sensor)
• Damaged sensor
• Improper harness connection
• Damaged PCM
STEP INSPECTION
ACTION
1 CHECK ECT AND IAT OUTPUT WITH NGS
TESTER
• Key off.
• Disconnect suspected temperature sensor.
• Connect jum per wire between sensor
signal circuit and ground circuit at
temperature sensor vehicle harness
connector.
• NGS tester installed.
• Key on.
Yes
REPLACE suspect sensor.
REMOVE jumper.
RECONNECT vehicle harness.
RERUN OBD Test.
Note
• If any NGS tester communication problem
exists, remove jum per wire immediately
and go to step 3
No REMOVE jumper.
Go to next step.
• Access ECT or IAT PID.
•
Is ECT or IAT PID less than 0.2 volts
(greater than 120 ”C {248 °F})?
2 CHECK CONTINUITY OF SENSOR SIGNAL
AND GROUND CIRCUITS
• Key off.
• Disconnect suspected temperature sensor.
• Disconnect PCM. Inspect for damaged or
pushed out pins, corrosion, loose wire, etc.
Service as necessary.
• Install breakout box. Leave PCM
Yes REMOVE breakout box.
RECONNECT all components.
Go to next step.
disconnected.
• Measure resistance between sensor signal
circuit at temperature sensor vehicle
harness connector and Test Pin 38 or 39 at
breakout box.
• Measure resistance between ground circuit
at temperature sensor vehicle harness
connector and Test Pin 91 at breakout box.
• Is each resistance less than 5.0 ohms?
No SERVICE open circuit.
REMOVE breakout box.
RECONNECT all components.
RERUN OBD Test.
3 CHECK FOR SENSOR SIGNAL CIRCUIT
SHORTED TO CONSTANT VOLTAGE
• Key off.
• Disconnect suspected temperature sensor.
• Disconnect PCM. Inspect for damaged or
pushed out pins, corrosion, loose wires,
etc. Service as necessary.
• Install breakout box. Leave PCM
Yes REPLACE PCM.
REMOVE breakout box.
RECONNECT all components.
RERUN OBD Test.
disconnected.
• Measure resistance between sensor signal
circuit Test Pin 38 or 39 and constant
voltage circuit at breakout box.
• Is each resistance greater than 10,000
ohms?
No LOCATE and REPAIR short to constant voltage circuit.
RERUN OBD Test.
01—0 1 A -2 3