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 is confused about what gear the transmission is in. It's like when you think you're in first gear on your bike, but you're actually in third.
The Transmission Control Module (TCM) is detecting a mismatch between the gear position it expects and the actual gear position.
The P177B code is triggered when the Transmission Control Module (TCM) identifies a discrepancy between the displayed transmission position and the actual transmission position. This error can occur due to issues within the TCM itself or problems with the sensors and wiring that communicate the transmission's position.
• Check Engine Light illuminated
• Transmission not shifting properly
• Vehicle stuck in limp mode
• Faulty Transmission Control Module (TCM)
• Defective transmission position sensor
• Wiring issues or poor connections
TCM: Transmission Control Module
OBD-II: On-Board Diagnostics II
• Check for other related codes.
• Inspect transmission position sensor and wiring.
• Test the TCM for faults.
• Replace or repair faulty wiring or connectors.
• Replace defective transmission position sensor.
• Reprogram or replace the TCM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$200 - $1000
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regularly inspect transmission wiring.
• Ensure TCM software is up to date.
• Avoid harsh driving conditions that may stress the transmission.
Transmission Control Issue
• Have the vehicle inspected by a professional.
• Avoid driving at high speeds until the issue is resolved.
Check with your vehicle manufacturer for warranty coverage on transmission components.
This code has been associated with TCM issues in vehicles with electronic transmissions, particularly in models from the early 2000s onward.
Moderate – It is advisable to address this issue soon to prevent potential transmission damage.
Driving with a malfunctioning transmission can be dangerous. Always ensure your vehicle is in safe operating condition.
• Vehicle at operating temperature
• Transmission in drive mode
The Transmission Control Module (TCM) is typically located near the transmission or under the vehicle's dashboard.
Q: Can I drive with a P177B code?
A: It's not recommended to drive for long periods with this code, as it may lead to further transmission damage.
Q: Will resetting the code fix the problem?
A: Resetting the code may temporarily clear the warning, but it won't fix the underlying issue.
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