C15" Ect Sensor Circuit Malfunction - Suzuki GSX-R750 Service Manual

4-40 FI SYSTEM AND INTAKE AIR SYSTEM

"C15" ECT SENSOR CIRCUIT MALFUNCTION

DETECTED CONDITION
High engine coolant temp. (Low voltage – Low
resistance)
Low engine coolant temp. (High voltage – High
resistance)
INSPECTION
• Lift and support the fuel tank with its prop stay. ( 4-51)
1
Turn the ignition switch OFF.
Check the ECT sensor coupler for loose or poor contacts.
If OK, then measure the ECT sensor voltage at the wire
side coupler.
Disconnect the coupler and turn the ignition switch ON.
Measure the voltage between B/Bl wire terminal and
ground.
If OK, then measure the voltage between B/Bl wire termi-
nal and B/Br wire terminal.
ECT sensor voltage: 4.5 – 5.5 V
[ 09900-25008: Multi circuit tester
V Tester knob indication: Voltage (
Yes
2
Turn the ignition switch OFF.
Measure the ECT sensor resistance.
ECT sensor resistance: 2.3 – 2.6 kΩ Ω Ω Ω Ω at 20°C (68°F)
[ 09900-25008: Multi circuit tester
U Tester knob indication: Resistance (Ω Ω Ω Ω Ω )
Refer to page 5-8 for details.
Yes
B/Bl or B/Br wire open or shorted to ground, or poor k or n
connection. ( 4-25)
If wire and connection are OK, intermittent trouble or faulty ECM.
Recheck each terminal and wire harness for open circuit and
poor connection. ( 4-4)
+B/Bl – -Ground
(
+B/Bl – -B/Br
)
No Loose or poor contacts on
the ECM coupler.
Open or short circuit in the
B/Bl wire or B/Br wire.
(Terminal – Terminal)
No Replace the ECT sensor
with a new one.
Replace the ECM with a new one,
and inspect it again.
ECM couplers
POSSIBLE CAUSE
• B/Bl circuit shorted to ground.
• B/Br circuit open.
• ECT sensor malfunction.
• ECM malfunction.
)
1
B/Bl
2
Engine Coolant
20°C ( 68 °F)
50°C ( 122 °F)
80°C ( 176 °F)
110°C ( 230 °F)
B/Br
Resistance
Temp.
Approx. 2.45 kΩ
Approx. 0.811 kΩ
Approx. 0.318 kΩ
Approx. 0.142 kΩ
V