Diagnostic trouble code: P0509 "Overvoltage in control circuit of idle speed
regulator"
Item
Operation procedure
No.
Connect
the
1
adaptor, and turn the ignition switch to
"ON" position.
Disconnect the connector of idle speed
regulator and inspect with multimeter to
2
verify that the resistances between pin A
and D, pin B and C are 53±5.3Ω under
20 .
Verify that the circuits between pin A, B,
C, and D of idle speed regulator and 65#,
3
66#, 67#, and 64# pin of ECU are short
to power supply.
diagnostic
tester
G-52
Inspection
Follow-up procedure
results
and
Proceed to next step
Yes
Proceed to next step
No
Repair or replace the
Yes
Refer to diagnosis
No
Replace the step
motor.
wiring harness.
help.