What Does P1504 Mean?
The PCM has detected an open circuit in the idle speed control valve closing solenoid control circuit. The closing solenoid cannot be energized to reduce idle speed, preventing proper idle control.
Common Causes
35%
Broken wire or open circuit in closing solenoid control wiring
30%
Failed idle speed control valve closing solenoid coil
25%
Disconnected or corroded connector at ISC valve
10%
PCM driver circuit failure for closing solenoid
Diagnostic Steps
1
Step 1: Inspect ISC valve connector for proper connection, corrosion, or damaged pins
2
Step 2: Measure resistance of closing solenoid coil at ISC valve connector (typically 10-30 ohms)
3
Step 3: Check for battery voltage at ISC valve power supply wire with key on
4
Step 4: Back-probe PCM closing solenoid control wire and verify ground signal during commanded closure
5
Step 5: Test continuity of control circuit from ISC valve to PCM connector
Estimated Repair Cost
$100 - $450
Parts + labor, varies by vehicle and location
The PCM has detected an open circuit in the idle speed control valve closing solenoid control circuit. The closing solenoid cannot be energized to reduce idle speed, preventing proper idle control.
The most common cause of P1504 (Idle Speed Control Valve Closing Solenoid Control Open Circuit) is: Broken wire or open circuit in closing solenoid control wiring
Typical repair costs for P1504 range from $100 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Engine may idle too high and not return to normal idle speed. Vehicle may lurch forward when placed in gear if idle is excessively high.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1504 to identify the root cause.
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Quick Info
Category
Powertrain
System
Idle Speed Control
Difficulty
Type
Manufacturer
Recommended Tools
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