DTC 51 Stop Light Switch Circuit Malfunction
DESCRIPTION
In this system, the signal of the stop light switch is used to judge whether the stop light system is abnormal or not.
The stop light switch has a duplex system (signals STP and ST1-) to recognize the abnormality when the signals of depressing and releasing the brake pedal are detected simultaneously.
- The normal condition is shown in the table below.
| Signal | Brake Pedal Released | In Transition | Brake Pedal Depressed |
| STP | Off | On | On |
| ST1- | On | On | Off |
| DTC No. | DTC Detection Condition | Trouble Area |
| 51 | Conditions (a), (b) and (c) continue for 0.5 seconds or more(1 trip detection logic):
(a) Ignition switch is ON.
(b) Brake pedal is released.
(c) STP signal is off when ST1- signal is off. | Open or short in stop light switch signal circuit
Stop light switch
ECM
|
WIRING DIAGRAM
INSPECTION PROCEDURE
- Inspect the fuses for circuits related to this system before performing the following inspection procedure.
- Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, and other data from the time the malfunction occurred.
When using intelligent tester:
| 1.READ VALUE USING INTELLIGENT TESTER (STOP LIGHT SWITCH) |
Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON.
Enter the following menus: Powertrain / Engine and ECT / Data List / Stop Light SW.
- OK:
| Brake Pedal | Display |
| Depressed | Stop Light SW ON |
| Released | Stop Light SW OFF |
| OK | |
| |
| CHECK FOR INTERMITTENT PROBLEMS
|
|
| 2.CHECK ECM (STP, ST1- VOLTAGE) |
Turn the ignition switch to ON.
Measure the voltage according to the value(s) in the table below.
- Standard Voltage:
| Tester Connection | Brake Pedal Condition | Specified Condition |
| G61-19 (STP) - C101-14 (E1) | Depressed | 11 to 14 V |
| Released | Below 1.5 V |
| G62-11 (ST1-) - C101-14 (E1) | Depressed | Below 1.5 V |
| Released | 11 to 14 V |
Text in Illustration| *a | Brake pedal depressed |
| *b | Brake pedal released |
| *c | Component with harness connected
(ECM) |
| 3.INSPECT STOP LIGHT SWITCH |
Inspect the stop light switch (See page ).
| | REPLACE STOP LIGHT SWITCH
|
|
|
| 4.CHECK HARNESS AND CONNECTOR (ECM - STOP LIGHT SWITCH) |
Disconnect the stop light switch connector.
Disconnect the ECM connectors.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance (Check for Open):
| Tester Connection | Condition | Specified Condition |
| A5-1 - G61-19 (STP) | Always | Below 1 Ω |
| A5-3 - G62-11 (ST1-) | Always | Below 1 Ω |
- Standard Resistance (Check for Short):
| Tester Connection | Condition | Specified Condition |
| A5-1 or G61-19 (STP) - Body ground | Always | 10 kΩ or higher |
| A5-3 or G62-11 (ST1-) - Body ground | Always | 10 kΩ or higher |
Reconnect the stop light switch connector.
Reconnect the ECM connector.
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
| OK | |
| |
| REPAIR OR REPLACE POWER SOURCE CIRCUIT
|
|
When not using intelligent tester:
| 1.CHECK STOP LIGHT (OPERATION) |
Check if the stop lights go on and off normally when the brake pedal is depressed and released.
- OK:
- The stop lights go on and off normally.
| | REPAIR STOP LIGHT SWITCH CIRCUIT |
|
|
| 2.CHECK ECM (STP, ST1- VOLTAGE) |
Turn the ignition switch to ON.
Measure the voltage according to the value(s) in the table below.
- Standard Voltage:
| Tester Connection | Brake Pedal Condition | Specified Condition |
| G61-19 (STP) - C101-14 (E1) | Depressed | 11 to 14 V |
| Released | Below 1.5 V |
| G62-11 (ST1-) - C101-14 (E1) | Depressed | Below 1.5 V |
| Released | 11 to 14 V |
Text in Illustration| *a | Brake pedal depressed |
| *b | Brake pedal released |
| *c | Component with harness connected
(ECM) |
| 3.INSPECT STOP LIGHT SWITCH |
Inspect the stop light switch (See page ).
| | REPLACE STOP LIGHT SWITCH
|
|
|
| 4.CHECK HARNESS AND CONNECTOR (ECM - STOP LIGHT SWITCH) |
Disconnect the stop light switch connector.
Disconnect the ECM connectors.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance (Check for Open):
| Tester Connection | Condition | Specified Condition |
| A5-1 - G61-19 (STP) | Always | Below 1 Ω |
| A5-3 - G62-11 (ST1-) | Always | Below 1 Ω |
- Standard Resistance (Check for Short):
| Tester Connection | Condition | Specified Condition |
| A5-1 or G61-19 (STP) - Body ground | Always | 10 kΩ or higher |
| A5-3 or G62-11 (ST1-) - Body ground | Always | 10 kΩ or higher |
Reconnect the stop light switch connector.
Reconnect the ECM connector.
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
| OK | |
| |
| REPAIR OR REPLACE POWER SOURCE CIRCUIT
|
|
