Posted on January 17, 2017May 3, 2017 by Mia

P1518 – Intake Manifold Runner Control Fault Stuck Open (Ford, Lincoln, Mercury)

By Mia (Contact Me)
Last Updated 2017-05-03
ASE Master Tech

What Does Code P1518 Mean?

Many modern vehicles use an intake manifold runner control (IMRC) system to improve engine performance and fuel economy. This design uses a solenoid controlled actuator (or module) to open and close the intake manifold butterfly valves. Adjusting the valves allows for variation of the intake runner length and improved volumetric efficiency. The actuator is controlled by the powertrain control module (PCM) based on inputs from the throttle position sensor (TP) and crankshaft position sensor (CKP).

A typical IMRC actuator

(Courtesy: justanswer.com

Code P1518 is set when the PCM detects a problem with the intake manifold runner control system.

What are the common causes of code P1518?

• Mechanical problem with the intake manifold or linkage
• Failed IMRC actuator
• Wiring problems
• Faulty PCM

What are the symptoms of code P1518?

Symptoms associated with code P1518 may include poor engine performance and an illuminated check engine light.

How do you troubleshoot code P1518?

Start by visually inspecting the IMRC actuator and linkage. Look for damaged wiring, loose connections, binding linkage, etc. Repair as needed. Next, check for technical service bulletins (TSBs) about the concern. If no problems are found, move forward with a sequential diagnosis of the system. Refer to the manufacturer’s service information for the exact diagnostic process.

It’s a good idea to obtain the factory wiring diagram before proceeding with diagnosis. Autozone offers free online repair manuals for many vehicles under their repair help section (http://www.autozone.com/repairinfo) and ALLDATA offers single vehicle subscriptions (http://www.alldata.com/oe-info-student-and-diyer).

Test the power side of the circuit

Remove the IMRC actuator connector. Turn the vehicle ignition on and use a test light to check for power to the IMRC. To do this, connect a test light between the battery negative terminal and the IMRC B+ terminal on the harness side of the connector. The light should illuminate. If it does not, there is a problem on the power side of the circuit. Consult the factory wiring diagram and repair the power side of the circuit as necessary.

A typical IMRC wiring diagram.

(Courtesy: ALLDATA)

Check the ground side of the circuit

Remove the IMRC actuator connector. Turn the vehicle ignition off and use a test light to check for IMRC ground. Connect the test light between the battery positive terminal and the IMRC ground terminal on the harness side of the connector. The light should illuminate. If it does not, there is a problem on the ground side of the circuit. Consult the factory wiring diagram and repair the ground side of the circuit as necessary.

Check the signal and monitor portions of the circuit

Remove the IMRC actuator connector. Use a digital multimeter set to ohms to check for continuity between the PCM and IMRC actuator. To do this, connect the meter between the IMRC signal terminal on the PCM and the signal terminal on the harness side of the IMRC connector. The meter should read a numeric value. If the meter read out of limits (OL) there is an open circuit. Consult the factory wiring diagram and repair the power side of the circuit as necessary.

If the circuit between the PCM and IMRC actuator is good, you’ll want to check that the PCM is supplying power to the IMRC. To do this, turn the ignition on and set the meter to read volts. Connect the negative meter lead to the battery ground terminal and the positive meter lead to the IMRC signal terminal on the PCM. Command the IMRC actuator on using an OEM equivalent scan tool. The meter should read around 5 volts. If it does not, there is a problem with a PCM or its programming. However, PCMs rarely go bad, so it’s a good idea to double check your work up to this point.

To test the monitor portion of the circuit, remove the IMRC actuator connector. Use a digital multimeter set to ohms to check for continuity between the PCM and IMRC actuator. To do this, connect the meter between the IMRC monitor terminal on the PCM and the monitor terminal on the harness side of the IMRC connector. The meter should read a numeric value. If the meter read out of limits (OL) there is an open circuit. Consult the factory wiring diagram and repair the power side of the circuit as necessary.A typical IMRC connector diagram.

(Courtesy: ALLDATA)

Check the actuator

Check the actuator by commanding it on with an OEM equivalent scan tool. If everything has tested OK up to this point and the actuator does not move, the actuator is probably faulty and should be replaced.

Codes Related to P1518

• DTC P1516: Intake Manifold Runner Control Input Error Bank 1
• DTC P1517: Intake Manifold Runner Control Input Error Bank 2
• DTC P1519: Intake Manifold Runner Control Fault Stuck Closed
• DTC P1520: Intake Manifold Runner Control Circuit Fault

Other Manufacturer Specific Definitions for P1518

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