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Error Code P1518 – Symptoms, Causes and Solutions

Many modern vehicles use an intake manifold channel control system. (IMRC) to improve engine performance and fuel economy. This design uses a solenoid-controlled actuator (or module) to open and close the intake manifold throttle valves. Error Code P1518

 

Valve adjustment allows the length of the intake channel to be varied and improves volumetric efficiency. The actuator is controlled by the powertrain control module (PCM) based on throttle position sensor inputs (TP) and crankshaft position sensor (CKP).

Definition

P1518 is an OBD-II code which refers to the failure of intake manifold runners stuck open control (Ford, Lincoln, Mercury)

Meaning

A code P1518 is a manufacturer-specific diagnostic trouble code that occurs when the PCM/ECM detects a problem with the IMRC. Each cylinder has two intake air passages, which are made of aluminum and one passage is always open while the other is opened and closed with a butterfly valve plate.

Reads: Error Code P1320 – Ignition Coil and Power Transistor

The housing uses a return spring to keep the plates closed. The motorized actuator houses internal switches to provide feedback to the Powertrain Control Module (PCM) indicating the position of the link and the plates.

This will allow the actuator vacuum to vent and the throttle valve plates to open. The Diagnostic Trouble Code (DTC) is set when the IMRC is commanded to close, but the IMRC monitor indicates open.

What are the common causes of code P1518?

  • A mechanical problem with intake manifold or link
  • IMRC actuator failed
  • Wiring problems
  • PCM failure

Symptoms

The symptoms of a P1518 code are:

  • Poor engine performance
  • Check engine light illuminated

Common mistakes

The following are some of the most common mistakes a technician can make when diagnosing a P1518 code:

  • Failure to thoroughly inspect the IMRC for damage.
  • Do not check the voltage at the IMRC connector.
  • Check the resistance and correct operation of the IMRC actuator without first checking the battery.
  • The intake manifold control (IMRC) valve position is not checked with a scan tool.
  • Do not clear the codes and perform a drive cycle before performing other tests.

How serious is this?

A code P1518 It is considered not serious. However, it can cause poor engine performance and an illuminated check engine light and should be addressed as soon as possible.

How do you fix the P1518 code?

Start by visually inspecting the actuator (IMRC) and the link. Look for damaged cables, loose connections, stuck coupling, etc. Repair what is necessary. Next, look for technical service bulletins (TSBs) about the problem.

If no problems are found, proceed with a sequential system diagnosis. Consult the manufacturer’s service information for the exact diagnostic process. It is a good idea to obtain the factory wiring diagram before proceeding to diagnosis.

Test the power side of the circuit

Remove the connector from the IMRC actuator. Turn on the vehicle’s ignition and use a test light to check power to the IMRC.

To do this, connect a test light between the negative battery terminal and the terminal B+ of the IMRC on the harness side of the connector. The light should illuminate. If it doesn’t, there is a problem on the power side of the circuit.

 

Check the ground side of the circuit

Remove the connector from the IMRC actuator. Turn off the vehicle’s ignition and use a test light to check the IMRC ground connection.

Connect the test light between the positive terminal of the battery and the ground terminal of the IMRC on the harness side of the connector. The light should illuminate. If it doesn’t, there is a problem on the ground side of the circuit.

Check the signal and monitor parts of the circuit

Remove the connector from the IMRC actuator. Use a digital multimeter set to ohms to check the continuity between the PCM and the 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.

If the circuit between the PCM and the IMRC actuator is OK, you will want to check that the PCM is supplying power to the IMRC. For it, turn on the ignition and set the meter to read volts. Connect the negative gauge lead to the battery ground terminal and the positive gauge lead to the IMRC signal terminal on the PCM.

 

Power on the IMRC actuator using an OEM equivalent scan tool. The meter should read around 5 volts. If it doesn’t, there is a problem with the PCM or its programming. However, the PCMs rarely break down, 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 connector from the IMRC actuator. Uses a digital multimeter set to ohms to check continuity between the PCM and the 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 numerical value.

Check the actuator

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

If you want to know other articles similar to Error Code P1518 – Stuck Intake Manifold Spool Control Failure (Ford, Lincoln, Mercury) you can visit the category Fault Codes.

 

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