Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
The car's computer that helps control the transmission is having trouble keeping track of time, like a clock that's not working right.
This code indicates that the Transmission Control Module (TCM) has detected a problem with its internal watchdog timer, which is used to monitor the module's operations.
The P171B code is set when the TCM detects an error in its internal watchdog timer. The watchdog timer is a safety mechanism that ensures the TCM is functioning correctly by monitoring its operations and resetting the system if it detects a fault. A run-time error indicates that the TCM's operations are not being monitored correctly, which could lead to transmission control issues.
• Check Engine Light is on
• Transmission may not shift properly
• Vehicle may go into limp mode
• Faulty Transmission Control Module (TCM)
• Software glitch or corruption in the TCM
• Electrical issues such as poor connections or damaged wiring
Transmission Control Module (TCM): A computer that controls the operation of the transmission.
Watchdog Timer: A safety feature that monitors the operation of a system to ensure it is functioning correctly.
• Use an OBD-II scanner to confirm the code.
• Inspect the TCM and its wiring for damage or poor connections.
• Check for any software updates for the TCM.
• Repair or replace any damaged wiring or connectors.
• Reprogram or update the TCM software.
• Replace the TCM if it is faulty.
• OBD-II scanner
• Multimeter
• Screwdriver set
$300 - $1200
Moderate
• Ford F-150
• Chevrolet Silverado
• Dodge Ram
• Regularly update vehicle software.
• Inspect wiring and connectors for wear.
• Avoid harsh driving conditions that may affect the transmission.
Transmission Control Module Issue
• Have the vehicle inspected by a professional.
• Avoid driving the vehicle if it is in limp mode.
• Keep up with regular vehicle maintenance.
Check with the vehicle manufacturer for potential recalls or warranty coverage related to the TCM.
This code has been associated with vehicles that have experienced TCM failures due to software issues or electrical faults.
Moderate – Address the issue soon to avoid potential transmission damage.
Driving with a malfunctioning TCM can lead to unsafe driving conditions. It is recommended to have the issue addressed promptly.
• Vehicle at operating temperature
• Engine running
The Transmission Control Module is typically located near the transmission or under the hood in the engine compartment.
Q: Can I drive with a P171B code?
A: It's not recommended to drive with this code as it can lead to transmission issues and unsafe driving conditions.
Q: How do I reset the TCM?
A: Resetting the TCM typically requires a professional scan tool or a software update. It's best done by a qualified technician.
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