Fix P0765: Mechanic’s solutions that WORKED

The P0765: Shift Solenoid “D” Malfunction code indicates a problem with the Shift Solenoid “D.” This solenoid is part of the transmission system and is responsible for controlling the flow of hydraulic fluid to engage the correct gears. A malfunction in this solenoid can lead to issues with gear shifting, such as harsh or delayed shifts, or even getting stuck in a single gear.

P0765 quick overview

Meaning	P0765: Shift Solenoid “D” Malfunction
Is it serious?	This code is serious as it can affect the vehicle’s transmission performance, leading to noticeable issues in gear shifting.
Possible causes	– Faulty or sticking shift solenoid “D” – Wiring or connector issues affecting the solenoid – Transmission Control Module (TCM) malfunctions – Hydraulic blockages within the transmission – Mechanical problems inside the transmission
How to diagnose?	Inspect Solenoid and Circuit: Check the solenoid for proper operation and resistance. Examine Wiring and Connectors: Look for damage, corrosion, or loose connections in the wiring harness. Perform Solenoid Function Test: Use a diagnostic scanner to activate the solenoid and observe its function. Load Test Circuits: Conduct a load test on the solenoid circuits to ensure they can handle the required current. Check TCM for Faults: Assess the Transmission Control Module for any issues or need for updates.

How to fix P0765 – learn from mechanics

I looked into P0765 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Chrysler

Vehicle Information:
2005 Chrysler 300 Limited 3.5L

Issue + Repair History:

• Vehicle had a P0765 code and under-drive solenoid issues.
• Experienced a circuit problem.
• Transmission with metal in the pan was replaced with a used one, but the code persisted.

Other OBD2 Codes + Test Results:

• Conducted load testing of circuits which were found to be good.
• Tested solenoid pack ohms.

Suggestions to Fix Issue:

• Check if the ECM shuts down the relay when detecting a fault.
• Consider replacing the solenoid/pressure switch and installing a new connector.
• Investigate if there is a UD solenoid circuit problem.
• Explore possibilities including the solenoid pack, ECM, connectors, or harness issues.
• Check solenoid specifications and consider the possibility of contaminated fluid affecting solenoid operation.

Final Fix:

• The car required a new ECM.
• A used ECM was bought, and programmed by a dealer resolved the issue.
• Learned that the transmission relay is shut off by the ECM when it detects a problem.

Case #2: Dodge

Vehicle Information:
2002 Dodge Ram 1500 SLT 4.7L

Issue + Repair History:

• The truck had issues with not upshifting to Overdrive.
• Encountered codes P0876 and P0765.
• Initially replaced the solenoid pack assembly.
• The P0765 code was resolved, but P0876 persisted.
• Replaced transmission with a used unit, but the problem remained.

Other OBD2 Codes + Test Results:

• Code P0876 for UD (Underdrive) sense circuit.

Suggestions to Fix Issue:

• Considering replacing the Transmission Control Module (TCM) if wiring and solenoid pack replacement didn’t resolve the issue.
• Ensure that wiring repairs, including pin terminals, are correctly executed.
• Check wires at the TCM for any pin or connector issues.
• Evaluate the O/D switch contacts in the gear selector for potential issues.

Final Fix:

• Replacing the Transmission Control Module (TCM) resolved the issue.

Case #3: Toyota

Vehicle Information:
2002 Toyota Camry SE 2.4L

Issue + Repair History:

• Vehicle was towed in with the customer reporting that the transmission was shifting poorly.
• Road test showed the transmission seemed to shift okay.
• Check Engine Light was on with codes P0765 & P0770.
• Transmission fluid was found to be burnt.

Other OBD2 Codes + Test Results:

• P0765 and P0770, indicating potential solenoid issues.

Suggestions to Fix Issue:

• Recommendations included tearing down the transmission due to burnt clutches, or considering a complete rebuild or replacement of the transmission.
• Checking solenoids and electrical connectors at the transmission was also suggested.

Final Fix:

• Solenoids were checked and found to be okay at the time.
• Electrical connectors at the transmission were inspected.
• A transmission flush was performed, and the fluid and filter were replaced, which resolved the issue temporarily.
• A follow-up was planned in case the vehicle returned with further issues.

Case #4: Lexus

Vehicle Information:
2001 Lexus RX300 3.0L

Issue + Repair History:

• Transmission had a code P0765 indicating Solenoid S4 was out of specs.
• The oil didn’t look contaminated.
• There was uncertainty about whether the issue was with the transmission or the computer.

Other OBD2 Codes + Test Results:

• P0765.

Suggestions to Fix Issue:

• Suggestions included checking the wiring and solenoids for clicking when heated.
• Testing for pump activity by removing a cooler line.
• Inspecting the filter element for clogging or deterioration.

Final Fix:

• Despite initial checks showing no issues, a deeper inspection revealed the filter was extremely contaminated.
• The filter, which looked like a felt filter, was actually a wire mesh filter completely clogged, preventing fluid from passing through.
• The transmission was taken down for this inspection and subsequent repair.

Case #5: Plymouth

Vehicle Information:
2000 Plymouth Voyager 3.3L

Issue + Repair History:

• Transmission would shift into reverse and first gear, but seemed to fail when trying to shift into second.
• Transmission relay dropped out, causing the check engine light to come on with codes P0765 and P0700.
• Solenoid pack was new, replaced at the last point of repair.
• Speed sensors checked.
• There was an assumption that the Transmission Control Module (TCM) might be bad.

Other OBD2 Codes + Test Results:

• P0765
• P0700

Suggestions to Fix Issue:

• Checking the solenoid pack, especially the second gear solenoid, for resistance.
• Checking the integrity of the circuit with a tail light bulb instead of a test light or ohm meter.
• Inspecting connectors for looseness or poor connections.

Final Fix:

• Replacing the brand new solenoid pack fixed the issue.
• The second gear solenoid in the new pack was found to have resistance out of specification, even though it was initially energized without faults detected by the scanner.
• No problems reported since the replacement of the solenoid pack.

Advice	Diagnostic Step Description
Check Solenoid Pack and Circuits	Verify the operation and resistance of the solenoids in the pack; ensure no issues with the solenoid pack.
Inspect Wiring and Connectors	Examine wiring and connectors for damage, looseness, or poor connections.
Consider TCM (Transmission Control Module) Issues	If solenoid pack and wiring are good, consider possible malfunctioning TCM.
Load Test Circuits	Perform a load test on the solenoid circuits to ensure they handle required current.
Replace Solenoid Pack if Needed	If tests indicate a problem, replace the solenoid pack, preferably with OEM parts.
Check for Pinched or Damaged Wires	Look for pinched, frayed, or damaged wires affecting solenoid operation.
Check for Software Updates	Ensure the vehicle’s software is up to date for potential issue resolution.
Consider Mechanical Issues	Some cases may require inspecting for mechanical problems within the transmission.