Sonata V6-3.0L (1991)
Electronic Control Unit: Customer Interest
Engine - Idle Surge/Rough Idle
Group: ENGINE ELECTRICAL
Number: 95-36-002
Date: JUNE, 1995
Model: ELANTRA(All) (1.6L & 1.8L)
SONATA (All) (2.0L & 3.0L)
SUBJECT:
ISC Servo (Stepper Motor) Troubleshooting
CONDITION:
1)
Poor driveability (rough idle, stalling, etc.) or:
2)
The vehicle's idle speed remains higher than normal and may surge rhythmically.
CORRECTION:
Using the Hyundai Scanner call up the service data for the stepper motor # 45 and engine rpm (crank angle) # 22.
Start the engine and bring to operating temperature. With the engine idling, turn the headlights on and observe the service data from the scanner. If, with
the lights on, the engine does not maintain specified idle speed, the stepper motor may be inoperative.
NOTE:
The stepper motor service data read by the scanner is the command signal to the stepper motor, and is not the actual stepper motor position.
CAUTION:
A short circuit in either coil winding of the stepper motor may result in damage to the ECM. If a vehicle displays the above symptoms, DO NOT
simply replace the ECM without first performing the operation below.
1.
If the stepper motor is still inoperative following the throttle body repair, perform the following:
A) Run a sweep test using the HDS machine to verify harness wiring and ECM output. Repair as necessary. NOTE: If ISC needs replacement,
proceed to Step # 3.
B) If an HDS machine is not available, you may also verify the condition of the coils by disconnecting the stepper motor connector and measuring
the winding resistances using a DVOM as shown below.
IDLE SPEED CONTROL SERVO CONTINUITY CHECK Measure the resistance between each of the terminals: STANDARD RESISTANCE:
Between terminal 2 and terminal 1 28-40 OHM (at 20°C (68°F)
Between terminal 2 and terminal 3 28-40 OHM (at 20°C (68°F)
Between terminal 5 and terminal 6 28-40 OHM (at 20°C (68°F)
Between terminal 5 and terminal 4 28-40 OHM (at 20°C (68°F)
If resistance is within specifications, proceed to Step 6.
