P1721

P1721 Vehicle Speed Signal

Description

The vehicle speed signal is transmitted from combination meter to TCM by CAN communication line. The signal functions as an auxiliary device to the output speed sensor when it is malfunctioning. The TCM will then use the vehicle speed signal.

SDT Reference Value in Data List Mode






On Board Diagnosis Logic

- This is not an OBD-II self-diagnostic item.
- Diagnostic trouble code "P1721" with SDT is detected when TCM does not receive the proper vehicle speed signal (input by CAN communication) from combination meter.

Possible Cause

Harness or connectors

(The sensor circuit is open or shorted.)

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 Turn ignition switch "ON". (Do not start engine.)
2 Select "Data list" mode for "AT" with SDT.
3 Start engine and maintain the following conditions for at least 5 consecutive seconds.
ACCELE POSI: 1/8 or less
VHCL/S SE-A/T: 30 km/h (19 MPH) or more
4 If DTC is detected, go to "Diagnosis Procedure".

Diagnosis Procedure

1. CHECK CAN COMMUNICATION LINE

Perform the "DTC check". Refer to [SDT Function (AT)] Scan Tool Testing and Procedures.

Is malfunction in the CAN communication indicated in the result?
YES
Check CAN communication line. Refer to [Meter System: System Description] Automatic Transmission/Transaxle.
NO
GO TO 2.

2. CHECK INPUT SIGNAL

With SDT
1 Start engine.
2 Select "ECU INPUT SIGNALS" in "Data list" mode for "AT" with SDT.
3 Drive vehicle and read out the value of "VHCL/S SE-MTR".

OK or NG
OK
GO TO 4.
NG
GO TO 3.

3. CHECK COMBINATION METERS

Check combination meters. Refer to Meter System Description.

OK or NG
OK
GO TO 4.
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 5.

5. 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 6.
NG
Repair or replace damaged parts.

6. 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.