P1774

P1774 Low Coast Brake Solenoid

Description

- Low coast brake solenoid valve is turned "ON" or "OFF" by the TCM in response to signals sent from the transmission range switch, output speed sensor and accelerator pedal position sensor (throttle position sensor). Gears will then be shifted to the optimum position.
- This is not only caused by electrical malfunction (circuits open or shorted) but also by mechanical malfunction such as control valve sticking, improper solenoid valve operation.

SDT Reference Value in Data List Mode

[P1772 Low Coast Brake Solenoid] Shift Mechanism Shift Mechanism Shift Mechanism Shift Mechanism





On Board Diagnosis Logic

- This is an OBD-II self-diagnostic item.
- Diagnostic trouble code "P1774" with SDT or 7th judgment flicker without SDT is detected under the following conditions.

- When TCM detects that actual gear ratio is irregular, and relation between gear position and condition of ATF pressure switch 2 is irregular during depressing accelerator pedal. (Other than during shift change)
- When TCM detects that relation between gear position and condition of ATF pressure switch 2 is irregular during releasing accelerator pedal. (Other than during shift change)

Possible Cause

- Harness or connectors
(The solenoid and switch circuits are open or shorted.)
- Low coast brake solenoid valve
- ATF pressure switch 2

DTC Confirmation Procedure

CAUTION:

Always drive vehicle at a safe speed.

NOTE:

If "DTC Confirmation Procedure" has been previously performed, always turn ignition switch "OFF" and wait at least 10 seconds before performing the next test.

After the repair, perform the following procedure to confirm the malfunction is eliminated.

with SDT

1 Start engine.
2 Accelerate vehicle to maintain the following conditions.
SLCT LVR POSI: "1" or "2" position
GEAR: "1st" or "2nd" (LC/B ON/OFF)
3 Perform step "2" again.
4 Turn ignition switch "OFF", then perform step "1" to "3" again.
5 Check "DTC check" mode for "AT" with SDT. If DTC (P1774) is detected, refer to "Diagnosis Procedure".
If DTC (P1772) is detected, go to P1772.

with GST

Follow the procedure "WITH SDT".

Diagnosis Procedure

1. CHECK INPUT SIGNALS

With SDT
1 Start the engine.
2 Select "SELECTION FROM MENU" in "Data list" mode for "AT" with SDT.
3 Drive vehicle in the "1" or "2" position ("11" or "22" gear), and confirm the ON/OFF actuation of the "ATF PRES SW 2" and "ON OFF SOL".

OK or NG
OK
GO TO 4.
NG
GO TO 2.

2. CHECK TCM POWER SUPPLY AND GROUND CIRCUIT

Check TCM power supply and ground circuit. Refer to [Main Power Supply and Ground Circuit Check] Main Power Supply and Ground Circuit Check.

OK or NG
OK
GO TO 3.
NG
Repair or replace damaged parts.

3. DETECT MALFUNCTIONING ITEM

Check the following.
- The A/T assembly harness connector pin terminals for damage or loose connection with harness connector.

OK or NG
OK
Replace the control valve with TCM. Refer to [Control Valve with TCM: Removal and Installation] Service and Repair.
NG
Repair or replace damaged parts.

4. CHECK DTC

Perform "DTC Confirmation Procedure".
- Refer to "DTC Confirmation Procedure".

OK or NG
OK
INSPECTION END
NG
GO TO 2.