how to diagnose P0790 code on Ford Explorer Sixth Generation (2020-present)?

Ford Explorer Sixth Generation (2020-present)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

Error Code: P0790

3 min read

522 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix P0790 code related to the vehicle speed sensor on Ford Explorer. Step-by-step guide with diagnostic procedures and repair instructions.

Error Code

P0790

Affected Component

Transmission

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect battery before working on electrical systems.
•Allow the engine to cool before working on the transmission.

Symptoms

•Check engine light illuminated
•Erratic or harsh shifting of the transmission
•Speedometer malfunctioning or reading incorrectly
•Transmission slipping or failing to engage
•Poor fuel economy

Diagnostic Steps

1
Scan the vehicle’s OBD-II system to confirm the presence of the P0790 code and check for any additional codes.
2
Inspect the vehicle speed sensor wiring and connectors for any visible damage, corrosion, or loose connections.
3
Use a multimeter to test the voltage and ground at the vehicle speed sensor connector.
4
Monitor the vehicle speed sensor signal with a scan tool while driving to ensure it is providing accurate readings.
5
Check the Transmission Control Module (TCM) for any software updates that may be required.
6
Verify the integrity of the TCM wiring harness and connectors, ensuring there are no shorts or open circuits.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•OBD-II scanner
•Multimeter
•Socket set
•Torque wrench
•Screwdrivers

Parts Required

•Vehicle speed sensor (if defective)

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Diagnostic Steps

1
Scan the vehicle’s OBD-II system to confirm the presence of the P0790 code and check for any additional codes.
2
Inspect the vehicle speed sensor wiring and connectors for any visible damage, corrosion, or loose connections.
3
Use a multimeter to test the voltage and ground at the vehicle speed sensor connector.
4
Monitor the vehicle speed sensor signal with a scan tool while driving to ensure it is providing accurate readings.
5
Check the Transmission Control Module (TCM) for any software updates that may be required.
6
Verify the integrity of the TCM wiring harness and connectors, ensuring there are no shorts or open circuits.

Solution

1. Preparation

Gather necessary tools and parts.
Disconnect the vehicle battery to ensure safety while working on electrical components.

2. Inspect and Repair Wiring

Sub-steps:
1. Remove any protective covers to access the vehicle speed sensor and wiring.
2. Inspect the wiring for frays, breaks, or signs of wear.
3. Clean any corrosion from connectors using electrical contact cleaner.
4. Repair any damaged wires by splicing in new wire or replacing the entire harness if necessary.

3. Replace Vehicle Speed Sensor

Tools Required: Socket set, torque wrench, screwdrivers, multimeter
Sub-steps:
1. Locate the vehicle speed sensor on the transmission.
2. Disconnect the wiring harness from the sensor.
3. Remove the sensor from its mounting position using a socket set.
4. Install the new vehicle speed sensor, tightening it to the manufacturer’s specified torque.
5. Reconnect the wiring harness to the new sensor.

4. Reconnect Battery and Clear Codes

Sub-steps:
1. Reconnect the vehicle battery.
2. Use the OBD-II scanner to clear the P0790 code from the system.

5. Test Drive

Sub-steps:
1. Start the vehicle and allow it to reach operating temperature.
2. Perform a test drive to ensure smooth shifting and proper operation of the speedometer.
3. Monitor the OBD-II system for reoccurrence of the P0790 code.