P1574 is a manufacturer-specific powertrain code. Its exact definition depends entirely on the vehicle application, ranging from speed sensor discrepancies to brake switch circuits or throttle position sensor disagreements.
Because the monitored system varies by manufacturer, the exact factory definition must be verified before diagnosis. This code identifies a detected fault condition but does not automatically prove that a specific component has failed.
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Key Takeaways
- P1574 is a manufacturer-specific code with entirely different meanings depending on the vehicle make and model.
- On some Nissan and Infiniti applications, it indicates a discrepancy between ABS and transmission speed signals.
- On certain Chrysler, GM, and Ford applications, it may point to a stoplamp switch circuit or throttle position sensor disagreement.
- Accurate diagnosis requires verifying the exact factory definition for your specific vehicle before testing any components.
P1574 Code Description and Implications
P1574 is a manufacturer-specific diagnostic trouble code. Because it is not standardized across all vehicles, its exact definition and the monitored system depend entirely on the manufacturer and application.
Some Nissan and Infiniti applications: P1574 is defined as an ASCD Vehicle Speed Sensor fault. The engine control module detects a discrepancy between the vehicle speed signal from the ABS module and the signal from the transmission output speed sensor.
Certain Chrysler, Dodge, Jeep, and GM applications: P1574 indicates a Stoplamp Switch Circuit fault. The control module detects an electrical issue, such as an open or short, in the brake light switch circuit that signals when the brakes are applied.
Specific Ford, Lincoln, and Mercury applications: P1574 may represent a Throttle Position Sensor Disagreement Between Sensors. The powertrain control module detects that the voltage signals from the multiple throttle position sensors do not correlate within the expected range.
Common Causes of the P1574 Code
Because P1574 applies to entirely different systems depending on the vehicle, the possible causes vary significantly by application.
For Nissan/Infiniti speed sensor applications: Possible causes include a failing ABS wheel speed sensor, a faulty transmission output speed sensor, or damaged wiring in the communication network between the modules.
For Chrysler/GM stoplamp switch applications: A failed brake light switch, misadjusted switch plunger, blown stoplamp fuse, or damaged wiring in the brake switch circuit can trigger this code.
For Ford/Lincoln throttle sensor applications: A faulty throttle position sensor, a failing throttle body assembly, or corroded connectors at the sensor harness may cause the signals to disagree.
Symptoms Associated With P1574
Symptoms depend heavily on which system the code is monitoring in your specific vehicle.
On applications monitoring vehicle speed signals, the cruise control system may become disabled, and the speedometer may behave erratically or stop working.
On applications monitoring the stoplamp switch circuit, the brake lights may fail to illuminate, remain on constantly, or the cruise control may refuse to engage.
On applications monitoring throttle position sensors, the engine may enter a reduced-power limp mode, exhibit poor acceleration, or stall.
An illuminated Check Engine Light may appear, though MIL behavior and additional warning lights vary by manufacturer and system architecture.
Diagnosing the P1574 Trouble Code
Diagnosis must begin by confirming the exact factory definition for your specific make, model, and engine using manufacturer service information.
Retrieve the code and record any freeze-frame data or related error code using a scan tool capable of reading manufacturer-specific data.
For speed sensor applications, use a scan tool to monitor live data from both the ABS module and the transmission control module while driving to identify which speed signal is dropping out.
For stoplamp switch applications, inspect the brake lights for proper operation and test the brake switch circuit for continuity, reference voltage, and proper ground according to the manufacturer wiring diagram.
For throttle position sensor applications, monitor the live voltage or percentage data from both throttle position sensors while slowly depressing the accelerator pedal to check for correlation faults or signal dropouts.
Repairing the P1574 Issue
Repairs must follow the confirmed root cause identified during system-specific testing.
If a specific wheel speed sensor or transmission speed sensor fails the manufacturer diagnostic procedure, replace the confirmed faulty sensor and clear the codes.
If the brake light switch is misadjusted or fails electrical testing, replace the switch and verify proper pedal operation and brake light function.
If the throttle position sensor or throttle body assembly fails correlation testing, replace the component with one meeting the correct vehicle specification and perform any required relearn procedures.
Always repair any damaged wiring or corroded connectors found during the diagnostic process before replacing major control modules.
Cost Considerations for P1574 Repairs
Repair costs for P1574 vary widely based on the underlying fault, the specific vehicle application, and local labor rates.
Replacing a brake light switch or a single wheel speed sensor involves lower parts costs and moderate labor time.
Diagnosing and replacing an integrated throttle body assembly or accessing a transmission output speed sensor may require significantly more labor time depending on component accessibility.
Diagnostic time, required programming or relearn procedures, and exact parts pricing all influence the final expense.
Prevention Strategies for Future Occurrences
Preventative measures depend on the specific system monitored by your vehicle’s application of this code.
Keeping electrical connectors clean and ensuring wiring harnesses are securely routed away from heat and moving parts can help prevent circuit-related faults.
On applications using mechanical brake light switches, ensuring the brake pedal return spring functions correctly can prevent excessive wear on the switch plunger.
Adhering to the manufacturer’s maintenance schedule helps ensure related systems, such as the throttle body or wheel bearings, remain in proper operating condition.
Troubleshooting Tips and Best Practices
Never assume P1574 relates to the throttle body or speed sensors without first verifying the exact manufacturer definition for your vehicle.
Check for applicable technical service bulletins or software updates, as some manufacturers release PCM or ABS module recalibrations to address false correlation or speed signal codes.
If multiple speed or communication codes are present alongside P1574 on a Nissan or Infiniti, inspect the CAN communication network and shared module grounds before replacing individual sensors.
Verify that all aftermarket accessories, such as trailer wiring harnesses or remote starters, are not interfering with the brake switch or vehicle speed circuits.
More OBD-II Codes
| P1565 | P1555 | P1550 | P1546 |
| P1542 | P1529 | P1580 | P1586 |
| P1587 | P1588 | P1605 | P1606 |
| P0500 | P0501 | P0502 | P0503 |
| P0504 | P0505 | P0506 | P0507 |
| P0121 | P0222 | P1500 | P1501 |
Frequently Asked Questions
Is P1574 a generic or manufacturer-specific code?
P1574 is a manufacturer-specific code. Its exact definition and the monitored system depend entirely on the vehicle make, model, and application.
Can a bad brake light switch cause a P1574 code?
Yes. On certain Chrysler, GM, and other applications, P1574 indicates a stoplamp switch circuit fault. A failed or misadjusted brake light switch can trigger this code.
Will P1574 disable my cruise control?
Depending on the application, yes. On vehicles where P1574 monitors vehicle speed signals or the brake switch circuit, the cruise control system may be disabled as a safety precaution.
Is it safe to drive with the P1574 code active?
It depends on the underlying fault. If the code relates to a brake light switch circuit, your brake lights may not function, making driving unsafe. Always verify the exact application before driving.
Does P1574 always mean the throttle body is bad?
No. While some Ford applications use P1574 for throttle position sensor disagreements, many other manufacturers use this code for speed sensors or brake switch circuits. Never replace the throttle body without confirming the exact factory definition.
What Should You Do About the P1574 Code?
Confirm the exact factory definition and technical service bulletins for your specific vehicle application.
Follow the applicable manufacturer diagnostic procedure to test the relevant speed sensors, brake switch circuit, or throttle position sensors based on your vehicle’s specific system architecture.
Repair or replace the confirmed failed component, then retest the system to ensure the code does not return.
