Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer for the transmission is having trouble checking itself to make sure everything is working right.
The Transmission Control Module (TCM) performs a self-test to ensure it is functioning correctly. If it detects an error during this self-test, it triggers the P1748 code.
The P1748 code indicates that the Transmission Control Module (TCM) has detected a fault during its self-test routine. This could be due to internal TCM issues, software glitches, or communication errors with other modules.
• Check Engine Light is on
• Transmission may not shift properly
• Reduced fuel efficiency
• Faulty Transmission Control Module
• Software glitch in the TCM
• Poor electrical connections or wiring issues
TCM: Transmission Control Module
OBD-II: On-Board Diagnostics, Second Generation
• Use an OBD-II scanner to confirm the code.
• Inspect the TCM and related wiring for damage or corrosion.
• Check for any software updates for the TCM.
• Repair or replace damaged wiring or connectors.
• Reprogram or update the TCM software.
• Replace the TCM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$200 - $1000
Moderate
• Ford Explorer
• Lincoln Navigator
• Mercury Mountaineer
• Regular maintenance and inspection of the transmission system.
• Ensure software updates are applied to the TCM.
• Maintain clean and secure electrical connections.
Transmission Control System Issue
• Do not ignore the Check Engine Light.
• Have the vehicle diagnosed by a professional if unsure.
• Regularly check for software updates from the manufacturer.
Check with the vehicle manufacturer for warranty coverage on transmission components.
This code has been commonly associated with Ford and Lincoln vehicles, particularly in models from the early 2000s.
Moderate – It is important to address this issue to avoid potential transmission damage.
Driving with a malfunctioning transmission can lead to safety issues. Ensure repairs are made promptly.
• Vehicle must be in a safe and stable condition.
• Transmission fluid should be at the correct level.
The Transmission Control Module is typically located near the transmission or under the dashboard.
Q: Can I drive with a P1748 code?
A: It's not recommended to drive for extended periods with this code as it may lead to transmission issues.
Q: How do I reset the TCM?
A: Resetting the TCM often requires a professional OBD-II scanner or a visit to a dealership.
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