Pinpoint Test D: Electrical Pressure Control (EPC) Solenoid

WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Refer to the TRANSMISSION INTERNAL HARNESS illustration preceding these pinpoint tests.

NOTE: Read and record all DTCs. All Digital TR Sensor and VSS DTCs must be repaired before entering Output State Control (OSC).

D1 ELECTRONIC DIAGNOSTICS
- With the vehicle in NEUTRAL, position it on a hoist. Refer to JACKING & LIFTING .
- Key in OFF position.
- Vehicle in PARK.
- Check to make sure the transmission harness connector is fully seated, pins are fully engaged in the connector and in good condition before proceeding.
- Install Diagnostic Tool.
- Key in ON position.
- Enter the following diagnostic mode on the scan tool: Diagnostic Data Link.
- Enter the following diagnostic mode on the scan tool: PCM.
- Enter the following diagnostic mode on the scan tool: Active Command Modes.
- Enter the following diagnostic mode on the scan tool: Output State Control (OSC).
- Enter the following diagnostic mode on the scan tool: Trans-Bench Mode.
- Does the vehicle enter the Trans-Bench Mode?
Yes : GO to D2.

No : REPEAT procedure to enter Trans-Bench Mode. If vehicle did not enter OSC, REFER to the INTRODUCTION - GASOLINE article for diagnosis of PCM. If equipped with fire suppression system, GO to D9.
D2 SOLENOID FUNCTIONAL TEST
- Install 2,060 kPa (300 psi) pressure gauge into EPC tap.
- Monitor pressure gauge.
- Enter the following diagnostic mode on the scan tool: Parameter; EPC.
- Select value - 15, 30, 45, 60, 70 or 90 psi.
- Press "SEND".
- Select another value "0-90 psi".
- Press "SEND".
- Enter the following diagnostic mode on the scan tool: XXX.
- Press "SEND".
- Does the pressure reading match the commanded pressure?
Yes : CLEAR DTCs. REPEAT OBD Tests. If equipped with fire suppression system, GO to D9.

No : GO to D3.
D3 CHECK FOR BATTERY VOLTAGE
- Key in ON position.
- Measure the voltage on pin 6 at the transmission harness connector to chassis ground.
  
  Fig 1: Measuring Voltage On Pin 6 At Transmission Harness Connector To Chassis Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage 5 volts or less?
Yes : GO to D4.

No : CHECK for open or short circuit in harness. If equipped with fire suppression system, GO to D9.
D4 CHECK FOR BATTERY VOLTAGE
- Remove transmission fluid pan.
- Visually inspect the lead frame connectors for damage.
- Key in ON position.
- Measure the voltage with positive lead to VPWR solenoid pin and negative lead to a good ground.
  
  Fig 2: Measuring Voltage With Positive Lead To VPWR Solenoid Pin And Negative Lead To Good Ground
  Courtesy of FORD MOTOR CO.
- Is voltage greater than 10 volts?
Yes : GO to D5.

No : REPAIR the circuit. CLEAR the DTCs. REPEAT the OBD Tests. If equipped with fire suppression system, GO to D9.
D5 ELECTRICAL SIGNAL CHECK
- Measure the voltage with positive lead connected to VPWR solenoid pin and connect negative lead to the signal pin of the EPC solenoid.
  
  Fig 3: Measuring Voltage With Positive Lead Connected To VPWR Solenoid Pin
  Courtesy of FORD MOTOR CO.
- Turn the solenoids ON and OFF, while monitoring the voltage reading, solenoid state on the diagnostic tool (ON and OFF), listen for the solenoid to activate (click).
- Enter the following diagnostic mode on the scan tool: Trans-Bench Mode.
- Enter the following diagnostic mode on the scan tool: Parameter EPC.
- Select a value "0-90 psi".
- Press "SEND".
- Select another value "0-90 psi".
- Press "SEND".
- Enter the following diagnostic mode on the scan tool: XXX.
- Press "SEND".
- Does the voltage and solenoid state change?
Yes : GO to D6.

No : CHECK for open or short circuit in harness or PCM. If equipped with fire suppression system, GO to D9.
D6 CHECK LEAD FRAME SOLENOID CONNECTIONS
- Key in OFF position.
- Disconnect the lead frame.
- Inspect lead frame for damage.
- Using the special tool, check all the lead frame solenoid connections.
  
  Fig 4: Locating Lead Frame Connector Pins
  Courtesy of FORD MOTOR CO.
- Does the special tool go through any of the lead frame solenoid connector pins?
Yes : INSTALL a new lead frame and GO to D7.

No : GO to D7.
D7 CHECK SOLENOID RESISTANCE AT SOLENOID
- Measure the resistance of the EPC solenoid.
  
  Fig 5: Measuring Resistance Of EPC Solenoid
  Courtesy of FORD MOTOR CO.
- Is the resistance between 2.48 and 5.66 ohms?
Yes : GO to D8.

No : INSTALL a new solenoid. CLEAR the DTCs. REPEAT the OBD Tests. If equipped with fire suppression system, GO to D9.
D8 CHECK SOLENOID FOR SHORT TO GROUND
- Check for continuity between engine GROUND and the EPC solenoid terminals with ohmmeter or other low current tester (less than 200 milliamps). Connection should show infinite resistance (no continuity).
  
  Fig 6: Checking Continuity Between Engine Ground And EPC Solenoid Terminals
  Courtesy of FORD MOTOR CO.
- Is there continuity?
Yes : INSTALL a new solenoid. CLEAR the DTCs. REPEAT the OBD Tests. If equipped with fire suppression system, GO to D9.

No : REFER to DIAGNOSIS BY SYMPTOM INDEX for diagnosis of pressure concerns. If equipped with fire suppression system, GO to D9.
D9 REPOWER THE FIRE SUPPRESSION SYSTEM
- Verify that the fire suppression system is repowered. Refer to FIRE SUPPRESSION SYSTEM .
- Is the fire suppression system repowered?
Yes : Fire suppression system repowering is complete.

No : REFER to FIRE SUPPRESSION SYSTEM for fire suppression system depowering and repowering procedure.