Fix P0753: Mechanic’s solutions that WORKED

The code P0753: Shift Solenoid A Electrical/Shift Solenoid A Circuit Electrical points out a fault in the transmission’s shift solenoid, and most likely is caused by wiring issues, solenoid malfunctions, or PCM/ECM problems.

P0753 quick overview

Meaning	P0753: Shift Solenoid A Electrical/Shift Solenoid A Circuit Electrical
Is it serious?	Yes, while it might not always lead to immediate driveability issues, it can potentially cause transmission performance problems or eventual transmission damage.
Possible causes	– Damaged or burnt wiring and harness, especially near hot areas like the exhaust manifold. – Malfunctioning or failed Shift Solenoid A. – Faulty PCM/ECM giving incorrect data or voltage readings. – Issues with related transmission components like the 3-4 servo piston spring. – Voltage discrepancies due to resistance in the circuit even if wiring appears intact.
How to diagnose?	1. Perform a visual inspection of the wiring and harness, especially around areas exposed to heat. 2. Conduct a resistance check on the solenoid circuit to ensure proper electrical flow. 3. Execute a voltage drop test on the solenoid circuit while it’s engaged. 4. Check the condition and functionality of Shift Solenoid A. Specifically, for the 3-4 servo piston spring, which can be accessed by removing the oil pan. 5. Road test the vehicle and toggle the OD switch at around 50 MPH to check if the transmission is correctly shifting between gears. 6. If all other tests and inspections prove inconclusive, consider the possibility of a faulty PCM/ECM and test or replace as necessary.
What is shift solenoid?	A shift solenoid is a small device in the automatic transmission of a vehicle that helps control the gear changes. It directs the flow of transmission fluid to engage different gears, allowing the car to shift smoothly.

How to fix P0753 – learn from mechanics

I looked into P0753 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: Chevrolet

Vehicle Information 1997 Chevrolet Blazer 4.3L

Issue + Repair History P0753 code indicating 1-2 shift solenoid A electrical malfunction. The vehicle shifts correctly according to the owner. Question arises on the possibility of changing the solenoid without removing the valve body.

What Are People Suggesting to Fix the Issue Replacing the shift solenoids, especially as they’re inexpensive. Care needed since one solenoid has a spring-loaded valve behind it. The shift solenoids are located at the rear of the valve body. Checking for a remote starter, which if present might be improperly installed. Bad ignition switch might cause such problems. Potential issues with wiring inside the pan. Monitoring the vehicle with tech 2 can help in diagnostics. Being cautious of false trans codes due to ignition switch problems.

What Was the Final Fix The solenoids were replaced without the need for valve body removal.

Case #2: Cadillac

Vehicle Information 2003 Cadillac Escalade ESV 6.0L

Issue + Repair History MIL (Malfunction Indicator Lamp) activated with no noticeable shift problems. Code provided: po753. Customer replaced A and B solenoids after transmission pan removal but problem persisted.

Other OBD2 Codes + Test Results Code mentioned: po753. Transmission fuse was confirmed to be in good condition.

Suggestions from the Community

1. Consider PCM reflash for transmission issues of that year.
2. Try running a jumper wire from battery to “E” wire at transmission to see if the code reappears.
3. Check for voltage loss to solenoids. Ensure no aftermarket equipment is sharing voltage with solenoids. Use a headlamp for proper voltage testing.
4. Monitor feedback voltage to ECM. When solenoid is on, feedback should be 0V, and 12V when off to determine if it’s a PCM fault or wiring.
5. Potential issue with the ignition switch.

Final Fix After ensuring continuity between the shift solenoid and PCM, and a transmission pan removal, it was noticed that the customer had not actually replaced the 1-2 solenoid as they claimed. The 1-2 shift solenoid was then replaced which resolved the problem.

Case #3: Jeep

Vehicle Information 1998 Jeep Grand Cherokee Laredo 4.0L

Issue + Repair History DTCs: PO463 (Fuel sender unit volts too high) and PO753 (Transmission 3-4 solenoid circuit). Technician evaluated transmission fluid level, found it low, and added two quarts of ATF. Tests on fuses, power to transmission relay, and ground were all okay. After clearing the codes, they reappeared immediately upon starting the engine.

Other OBD2 Codes + Test Results During a test drive with a scanner, data showed: Speed: 68 mph Output shaft RPM: 2960 Desired Governor pressure: 101 Actual Governor pressure: 50

Suggestions from the Community Possible problem in the wiring harness with open circuits for both solenoid control and fuel sender wires. The issue might be a 1-2 shift solenoid electrical problem. P0753 pertains to an electrical issue with the solenoid for 4th gear, and P0463 is related to the fuel level sender circuit. The technician suggested checking circuits with a wiring diagram and a DVOM, focusing first on the transmission. Another suggestion was that tire size or a lifted vehicle might trigger false codes.

Final Fix The problem was the 3-4 solenoid on the valve body. The technician noted it was challenging to replace due to the positioning of a screw holding the connector to the valve body. The fuel sender code has not reappeared.

Case #4: Ford

Vehicle Information 2005 Ford F-250 Super Duty XL 5.4L

Issue + Repair History DTCs: P0753 and P0973. Vehicle drops from 6th to 5th gear after warming up. Technician replaced coast and direct shift solenoids and internal harness. Voltage spikes observed on solenoids, mostly B solenoid during gear drops.

Suggestions from the Community Main wiring harness rubbing at the back of the engine near the PCM could cause similar issues. For P0753 (SSPC-A circuit failure) and P0973 (SSPC-A short to ground), suggested disconnecting connectors and load testing the return wire, also performing a wiggle test. Watching computer data may help understand if it’s commanding the shift. For instance, a drop in VSS reading or a spike in TPS voltage might command a downshift. Another case mentioned a trans harness burned near the rear of the right exhaust manifold causing similar symptoms and codes.

Final Fix Wiring harness had at some point dropped close to the exhaust manifold, melting insulation on four wires. After repositioning, checking, and repairing the harness, the issue was resolved.

Case #5: Dodge

Vehicle Information 1999 Dodge Dakota 3.9L

Issue + Repair History MIL lamp triggered by intermittent DTC P0753 (shift solenoid electrical problem). The solenoid had been replaced a few months earlier due to a different shift issue. Additionally, the transmission relay was replaced in attempts to fix the current problem, but the issue persisted. Wiring tests revealed specific resistance values between ECM terminals and relay, but the problem was not evident while the light was off.

Suggestions from the Community

• A mechanic suggested checking the 3-4 servo piston spring as a broken spring might be causing the issue. This can be done by removing the oil pan.
• Highlighted that older models might have wiring problems. Even if resistance checks out, it’s essential to do a voltage drop test on the solenoid circuit.
• The PCM could be the most frequent cause of this code. If all other tests are conclusive, and there are no wiring issues, the PCM might be the culprit, with internal “unexpected voltage conditions.”
• Starting with a transmission fluid quality and specification check was recommended. The TCM may not be the issue since the vehicle operates as expected.
• To validate if the transmission is shifting correctly in and out of 4th gear, it’s useful to road test the vehicle at about 50 MPH and toggle the OD switch. If there’s no noticeable shift difference, the PCM might need replacement. Also, there could be an intermittent short in the solenoid circuit, possibly even within the pan.

Final Fix After considering all feedback and suggestions, the technician decided to replace the ECM. All other components were testing well, leading to the conclusion that the ECM might be producing incorrect data.