Engine Electrical System

Diagnostic trouble code: P0508 “Undervoltage in control circuit of idle speed
regulator”
Item
No.
Operation procedure
Inspection
results
Follow-up
procedure
1
Connect the diagnostic tester and adaptor,
and turn the ignition switch to “ON”
position.
Proceed to next
step
Yes
Proceed to next
step
2
Disconnect the connector of idle speed
regulator and inspect with multimeter to
verify that the resistances between pin A
and D, pin B and C are 53±5.3Ω under
20.℃
No
Replace the step
motor.
Yes
Repair or replace
the wiring harness.
3
Verify that the circuits between pin A, B,
C, and D of idle speed regulator and 65#,
66#, 67#, and 64# pin of ECU are short to
ground.
No
Refer to diagnosis
help.
E-51
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