Mazda RX-8 Workshop Manual page 237

Turn the ignition switch off.
Disconnect the ECT sensor connector.
Inspect for poor connection (such as
damaged/pulled-out pins, corrosion).
Is there any malfunction?
CLASSIFY ECT SENSOR MALFUNCTION OR WIRING
4 HARNESS MALFUNCTION
Access the ECT PID using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [13B-
MSP].)
Connect a jumper wire between ECT
sensor terminal A and B (wiring harness-
side).
Verify the ECT PID value.
Is the voltage 4.58 V or below?
INSPECT PCM CONNECTOR FOR POOR CONNECTION
5
Turn the ignition switch off.
Disconnect the PCM connector.
Inspect for poor connection (such as
damaged/pulled-out pins, corrosion).
Is there any malfunction?
INSPECT ECT SENSOR SIGNAL CIRCUIT FOR SHORT
6
TO POWER SUPPLY
ECT sensor and PCM connectors are
disconnected.
Turn the ignition switch to the ON position
(engine off).
Measure the voltage between ECT sensor
terminal A (wiring harness-side) and body
ground.
Is the voltage B+?
INSPECT ECT SENSOR CIRCUIT FOR OPEN CIRCUIT
7
ECT sensor and PCM connectors are
disconnected.
Turn the ignition switch off.
Inspect for continuity between the
following circuits:
terminals, then go to Step 8.
No Go to the next step.
YesReplace the ECT sensor, then go to Step 8.
(See ENGINE COOLANT TEMPERATURE
(ECT) SENSOR REMOVAL/INSTALLATION
[13B-MSP].)
No Go to the next step.
YesRepair or replace the connector and/or
terminals, then go to Step 8.
No Go to the next step.
YesRepair or replace the wiring harness for a
possible power supply, then go to Step 8.
No Go to the next step.
YesGo to the next step.
No Repair or replace the wiring harness for a
possible open circuit, then go to the next
step.