Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic trouble code (DTC) information
Condition
The control module has a main relay which regulates supply voltage to the motors via four separate motor relays. If the main relay is not activated when a button is pressed in or if the relay is activated with all buttons are in the up position diagnostic trouble code (DTC) PSL/PSR-421 is set.
Possible Source
- Defective control module.
Fault symptom[s]
- One or more functions not working.
- Memory buttons do not function
- This diagnostic trouble code (DTC) may occur without any fault symptom being apparent.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
No obligation. See pricing before you book.