Test Procedure
WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
- FE1 DTCS P2531 AND P2535: CHECK FOR SELF-TEST DTCS
Are any of the following DTCs present during PCM or TCM self-test: P2531 or P2535?
Yes No For DTC P2531, GO to FE2.
For DTC P2535, GO to FE6.GO to FE8. - FE2 DTC P2531: CHECK THE ISP-R PID
- Access the PCM and monitor the IGN_R PID.
- Key ON, engine OFF.
Does the PID indicate YES (key in ISP-R position)?
Yes No Key in OFF position. Key in OFF position. GO to FE8. GO to FE3. - FE3 CHECK FUSES
- Inspect all the ignition switch related fuses.
Are the ignition switch fuses OK?
Yes No GO to FE4. INSTALL a new fuse as necessary.
GO to FE5. - FE4 CHECK THE IGNITION SWITCH AND HARNESS FOR AN OPEN
- PCM connector disconnected.
- Key ON, engine OFF.
- Measure the voltage between:
( + ) PCM Connector, Harness Side ( - ) Vehicle Battery ISP-R - Pin B22 Negative terminal
Is the voltage greater than 10.5 V?
Yes No Key in OFF position.
GO to FE9.Key in OFF position.
CHECK for a damaged ignition switch.
REFER to COMPONENT TESTING .
If the ignition switch is OK, REPAIR the open circuit. - FE5 CHECK THE ISP-R CIRCUIT FOR A SHORT TO GND IN THE HARNESS
- Ignition Switch connector disconnected.
- PCM connector disconnected.
- Measure the resistance between:
( + ) PCM Connector, Harness Side ( - ) Vehicle Battery ISP-R - Pin B22 Negative terminal
Is the resistance greater than 10K ohms?
Yes No CHECK the ignition switch for a short to ground. If OK,
GO to FE9.REPAIR the short circuit to GND. - FE6 DTC P2535: CHECK THE ISP-R/S PID
- Key ON, engine OFF.
Does the engine start with the ignition key in ON position?
Yes No GO to FE7. Key in OFF position.
GO to FE8. - FE7 CHECK THE ISP-R/S CIRCUIT FOR A SHORT TO POWER
- PCM connector disconnected.
- Key ON, engine OFF.
- Measure the voltage between:
( + ) PCM Connector, Harness Side ( - ) Vehicle Battery ISP-R/S - Pin B21 Negative terminal
Is the voltage less than 1 V?
Yes No Key in OFF position.
GO to FE9.Key in OFF position.
CHECK for a damaged ignition switch.
REFER to COMPONENT TESTING .
If the ignition switch is Ok, REPAIR the short to PWR circuit in the harness. - FE8 CHECK THE ISP-R AND ISP-R/S CIRCUIT FOR INTERMITTENT FAULTS
- Key ON, engine OFF.
- Access the PCM and monitor the IGN_R and IGN_R/S PIDs.
- Turn the key to the ON and START positions, while observing the related ignition PID.
- Carefully wiggle all accessible wiring and connectors associated with the circuit and look for a change in the PID state.
Is a concern present during the wiggle test?
Yes No Key in OFF position. Key in OFF position. REPAIR as necessary. GO to Pinpoint Test Z . - FE9 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Visually inspect for:
- pushed out pins.
- corrosion.
- Connect all the PCM connectors and make sure they seat correctly.
- Carry out the PCM self-test and verify the concern is still present.
Is the concern still present?
Yes No INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) . The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.