Code No.P2728: Pressure Control Solenoid SL4 System (Malfunction), P2729: Pressure Control Solenoid SL4 System (Low Current), P2730: Pressure Control Solenoid SL4 System (High Current)

OPERATION

Solenoid closes or opens according to the signals from the A/T-ECU.
The A/T-ECU energises or deenergises solenoid, based on input signals such as accelerator pedal position sensor opening angle, inhibitor switch, etc.

DIAGNOSIS CODE SET CONDITIONS

If a status continues with which the pressure control solenoid SL4 current differs from the A/T-ECU target value, code No.P2728 is set.
When the pressure control solenoid SL4 current is standard value or less, code No.P2729 is set.
When the pressure control solenoid SL4 current is standard value or more, code No.P2730 is set.

PROBABLE CAUSES

Malfunction of valve body (pressure control solenoid SL4)
Damaged harness wires and connectors
Malfunction of the A/T-ECU

DIAGNOSIS PROCEDURE

STEP 1. Measure the resistance at A/T-ECU connector.

Disconnect the connector, and measure the resistance between terminal SL4 line and terminal SL4G line at the harness side.

OK: 5.0 - 5.6 Ω (A/T fluid temperature 20°C)

Q. Is the check result normal?

	Go to Step 3.

	Go to Step 2.

STEP 2. Measure the resistance at transmission wiring harness connector.

Disconnect the connector, and measure the resistance between terminal SL4 line and terminal SL4G line at the transmission wiring harness side.

OK: 5.0 - 5.6 Ω (A/T fluid temperature 20°C)

Q. Is the check result normal?

	Go to Step 5.

	Go to Step 6.

STEP 3. Measure the resistance at A/T-ECU connector.

Disconnect the connector, and measure the resistance between terminal SL4 and body earth at the wiring harness side.
Disconnect the connector, and measure the resistance between terminal SL4G and body earth at the wiring harness side.

OK: No continuity

Q. Is the check result normal?

	Go to Step 8.

	Go to Step 4.

STEP 4. Measure the resistance at transmission wiring harness connector.

Disconnect the connector, and measure the resistance between terminal SL4 and body earth at the transmission assembly side.
Disconnect the connector, and measure the resistance between terminal SL4G and body earth at the transmission assembly side.

OK: No continuity

Q. Is the check result normal?

	Go to Step 5.

	Go to Step 6.

STEP 5. Check for open circuit, short circuit and harness damage in SL4, SL4G line between transmission wiring harness connector and A/T-ECU connector.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

	Repair the connector(s) or the wiring harness.

STEP 6. Check for open circuit, short circuit and harness damage in SL4, SL4G line between transmission wiring harness connector and pressure control solenoid SL4 connector.

Q. Is the check result normal?

	Go to Step 7.

	Repair or replace the transmission wiring harness.

STEP 7. Check the pressure control solenoid SL4.

Refer to

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

	Replace the valve body (pressure control solenoid SL4).

STEP 8. Check whether the diagnosis code is set again.

Ignition switch: "LOCK"(OFF) → "ON"
Check again if the diagnosis code is set.

Q. Is diagnosis code No.P2728, P2729, P2730 set?

	Replace the A/T-ECU.

	Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).