Pinpoint Test E: DTCS P093A, P093B, P093C, P093D

Refer to TRANSMISSION CONTROLS - 8F35 for schematic and connector information.

Normal Operation and Fault Conditions

For the start/stop system the 8F35/40 transmission comes equipped with an electronically controlled start-stop hydraulic accumulator that stores fluid pressure while the engine is running. During an auto start-stop event when the engine is off, the hydraulic accumulator holds on to the fluid and only releases the pressure into the transmission line pressure hydraulic circuit when the engine starts to crank or the customer releases the brake allowing the transmission to stay engaged while the main pump is not creating fluid pressure. This allows quick response time as the transmission reengages while the engine re-starts. The transmission auto start-stop accumulator is controlled by an on/off solenoid which, during a start stop event, is activated when the brake pedal is released and the engine RPM reaches 200 RPM, hydraulic pressure stored in the accumulator is released into the transmission line pressure passage. The solenoid is controlled by a "smart driver" chip. When the PCM commands the solenoid on, the smart driver returns fault information (open, short to power, short to ground). The auto start-stop accumulator solenoid operating voltage is between 9-18 volts.

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
PCM P093A:00	Hydraulic Accumulator Solenoid Circuit/Open: No Sub Type Information	This DTC sets if the PCM detects an open in the auto start-stop accumulator solenoid wiring or solenoid.
PCM P093B:00	Hydraulic Accumulator Solenoid Circuit Low: No Sub Type Information	This DTC sets if the PCM detects a short to ground in the auto start-stop accumulator solenoid wiring or solenoid.
PCM P093C:00	Hydraulic Accumulator Solenoid Circuit High: No Sub Type Information	This DTC sets in the PCM if the smart driver detects the circuit is high.
PCM P093D:00	Hydraulic Accumulator Solenoid Performance: No Sub Type Information	This DTC sets if the PCM detects a non electrical failure in the auto start-stop accumulator. CHECK for possible fluid contamination, accumulator failure, or an anti-backflow check valve leaking pressure.

Possible Sources

Connectors damaged or pushed-out terminals, corrosion, loose wires or ground and missing or damaged seals
Auto start-stop accumulator and/or solenoid
PCM

E1 RETRIEVE AND RECORD ALL DTCS

Using the diagnostic scan tool, retrieve all DTCs.

Are DTCs P093A, P093B, P093C, P093D present?

Yes	For DTC P093A, P093B, P093C, GO to E2 If no electrical DTCs are set, but DTC P093D is set, GO to E6

No	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or terminal issues.

E2 CHECK THE AUTO START-STOP ACCUMULATOR SOLENOID CIRCUITS FOR A SHORT TO GROUND

Ignition OFF.

Disconnect PCM C1915E.

Disconnect PCM C1915B.

Disconnect Auto Start-Stop Accumulator Solenoid C148.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1915B-60	Courtesy of FORD MOTOR COMPANY	Ground
C1915E-95	Courtesy of FORD MOTOR COMPANY	Ground

Are the resistances greater than 10, 000 ohms?

Yes

GO to E3

No	REPAIR the circuits.

E3 CHECK THE AUTO START-STOP ACCUMULATOR SOLENOID POWER CIRCUIT FOR AN OPEN

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1915B-60	Courtesy of FORD MOTOR COMPANY	C148-2
C1915E-95	Courtesy of FORD MOTOR COMPANY	C148-1

Are the resistances less than 3 ohms?

Yes

GO to E4

No	REPAIR the circuits.

E4 CHECK THE AUTO START-STOP ACCUMULATOR SOLENOID CIRCUITS FOR A SHORT TOGETHER

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1915B-60	Courtesy of FORD MOTOR COMPANY	C1915E-95

Is the resistance greater than 10, 000 ohms?

Yes

GO to E5

No	REPAIR the circuit

E5 CHECK THE AUTO START-STOP ACCUMULATOR SOLENOID FOR AN OPEN

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
auto start-stop accumulator solenoid, component side, pin 1	Courtesy of FORD MOTOR COMPANY	auto start-stop accumulator solenoid, component side, pin 2

Is the resistance between 17 and 19 ohms?

Yes

GO to E6

No	INSTALL a new auto start-stop accumulator solenoid.

E6 VERIFY THAT TRANSMISSION LINE PRESSURE IS NORMAL
- VERIFY that transmission line pressure is normal. PERFORM the line pressure test. REFER to: Special Testing Procedures .
Is the transmission line pressure within acceptable limits?

Yes GO to E7

No REPAIR as necessary.

E7 CHECK THE AUTO START STOP ACCUMULATOR HYDRAULIC PRESSURE RELEASE FUNCTION

Connect Pressure vacuum tester or 0-689 kPa (0-100 psi). pressure gauge to the front line pressure tap on top of the transmission.

Connect the diagnostic tool.

Ignition ON. Jumper:

Positive Lead	Measurement / Action	Negative Lead
Battery positive	Courtesy of FORD MOTOR COMPANY	C1915B-60

Calibrate the PVT or pressure gauge to 0.

Monitor the line pressure while touching the negative jumper to ground.

Positive Lead	Measurement / Action	Negative Lead
Ground	Courtesy of FORD MOTOR COMPANY	C1915E-95

Does the line pressure increase to more than 620 kPa (90 psi)?

Yes	REMOVE the jumper. Verify all PCM power circuits and fuses. If no problem is found, Refer to PCM GUIDED ROUTINE TESTING PROGRAM the PCM to the latest calibration level. PERFORM the Solenoid Body Strategy Data Download procedure. REFER to: Transmission Strategy Download .

No	REMOVE the jumper. INSTALL a new auto start-stop accumulator. REFER to: Auto-Start-Stop Accumulator .