1992-1996 Mitsubishi Diamante Door Lock Switch: Diagnosing and Fixing Failures
This guide covers the common symptoms, replacement steps, and buying advice for the door lock switch in your first-generation Mitsubishi Diamante.
- The biggest pitfall is confusing the driver's side (master) switch with the passenger side switch; they are not interchangeable.
- If the key fob works but the interior button doesn't, the switch is almost certainly the problem, not the more expensive lock actuators.
- Failure is typically due to simple age and wear; no specific recalls or TSBs are known for this part on the 1992-1996 Diamante.
- Replacement is a simple DIY job that requires removing the door panel. A used OEM switch is often the most practical and reliable option.
Symptoms of a Failing Door Lock Switch
When a door lock switch begins to fail in a 1992-1996 Mitsubishi Diamante, the symptoms can sometimes be confused with a bad door lock actuator. Understanding the signs can help you pinpoint the correct part for repair.
- Intermittent Operation: The locks may work sometimes but not others. You might have to press the button multiple times for it to respond. This is often the first sign of worn internal contacts.
- Complete Failure of All Locks: If the master switch on the driver's door fails, none of the power locks may respond to the switch. However, they might still work using the key in the door or with a keyless entry remote, if equipped.
- Only One Switch Works: The passenger switch might lock its door, but the driver's master switch does nothing. This points directly to a problem with the master switch itself.
- No Sound or Action: When you press a faulty switch, you will typically hear no sound from any of the doors. In contrast, a failing door lock actuator will often make a buzzing or clicking noise without actually moving the lock.
- Physical Damage: The rocker button itself can become loose, cracked, or broken from years of use, preventing it from making proper contact internally.
Known Issues, TSBs, and Recalls
For the 1992-1996 Mitsubishi Diamante, there are no known recalls or Technical Service Bulletins (TSBs) issued by the NHTSA specifically for the master or passenger door lock switches. Failures of this part are almost always attributed to the normal wear and tear of a component that is over 25 years old. The primary cause of failure is the wearing out of the internal electrical contacts from repeated use.
Pro Tip: If your locks work with the key fob (if you have one) but not the interior door switch, the problem is almost certainly the switch or its wiring, not the door lock actuators. This simple test can save you from buying the wrong part.
Buying a Used Door Lock Switch
Given the age of the first-generation Diamante, finding a new OEM or aftermarket door lock switch can be difficult, making a quality used part the most practical option. Here’s what to look for when buying a recycled OEM switch.
- Verify the Correct Side: The driver's side (master) switch and the passenger's side switch are different parts and are not interchangeable. The master switch has controls for all doors and often a window lock button, while the passenger switch is much simpler. Carefully compare photos to your original part before purchasing.
- Inspect the Connector and Pins: Check the electrical connector on the back of the switch. Ensure the plastic is not cracked or melted and that all the metal pins are present, straight, and free of corrosion.
- Check for Physical Wear: Look at the buttons themselves. Avoid switches with deep scratches, cracks, or excessive wobble. While cosmetic wear is expected, severe physical damage could indicate internal problems.
- Why Used OEM is a Good Choice: For a part like this, a used Original Equipment Manufacturer (OEM) switch is often a better choice than a cheap, new aftermarket part (if one can even be found). The OEM part was designed for a perfect fit and finish in your door panel, and its internal components are often of higher quality than generic replacements.
Cost Comparison
Pricing can vary based on availability and condition, which is a major factor for a vehicle of this vintage.
| Part Type | Estimated Cost |
|---|---|
| New OEM | $100 - $200+ (Likely discontinued and very difficult to find) |
| New Aftermarket | $30 - $70 (Availability is extremely limited or non-existent) |
| Used OEM | $25 - $75 |
| Shop Labor | $100 - $150 |
Step-by-Step Replacement Guide (Difficulty: 2/5)
Replacing the door lock switch is a straightforward job that most DIY mechanics can complete in under an hour. The main task is removing the interior door panel.
- Disconnect the Battery: Before starting any electrical work, disconnect the negative terminal from your car's battery to prevent short circuits.
- Locate and Remove Panel Screws: Look for screws holding the door panel in place. Common locations include inside the door pull handle recess, behind the interior door handle, and along the outer edges of the panel. There may be small plastic covers hiding these screws that need to be pried off with a small flathead screwdriver.
- Pry the Door Panel Loose: Once all screws are removed, use a panel removal tool or a flathead screwdriver (wrapped in tape to prevent scratching) to gently pry the panel away from the door frame. Start at the bottom and work your way around. You will hear the plastic clips pop as they release.
- Lift the Panel Up and Away: With the clips released, lift the panel straight up to unhook it from the top edge of the door near the window. Do not pull it away completely yet.
- Disconnect Electrical Connectors: Carefully look behind the panel and disconnect the electrical harnesses for the power window switch, door lock switch, and any door lights. These connectors have small tabs that must be pressed to release them.
- Remove the Old Switch: The door lock switch is typically held into the door panel with a few small screws or clips. Remove them and take the old switch out.
- Install the New Switch: Place the new switch into the door panel, secure it, and reconnect all electrical harnesses. Before re-installing the door panel, it's a good idea to temporarily reconnect the battery and test the new switch to ensure it works correctly.
- Reassemble: Re-hang the door panel on the top of the door, press the clips back into place, re-install the screws, and reconnect the battery terminal.
Warning: The plastic clips holding the door panel can be brittle on older vehicles. Use a proper panel removal tool and gentle, even pressure to minimize the risk of breaking them.
Frequently Asked Questions (FAQ)
My key fob locks the doors, but the button inside doesn't. Is it the switch?
Yes, this is a classic symptom of a failed master door lock switch. The fact that the locks respond to the remote means the actuators and the central locking module are working. The switch itself is the most likely point of failure.
Can I just clean the switch instead of replacing it?
While sometimes possible, it is generally not recommended. The switch is a sealed unit not designed to be opened. Even if you manage to get it apart, the internal contacts are likely worn beyond what cleaning can repair. Given the low cost of a used replacement, swapping the part is a more reliable and permanent fix.
Do I need to replace the passenger switch if I replace the driver's master switch?
No, the switches operate independently. You only need to replace the specific switch that has failed.
Why do my locks work with the key but not the power switch?
Using the key in the door cylinder mechanically operates the lock linkage for that specific door. The power lock switch, on the other hand, relies on an electrical circuit. This symptom confirms the mechanical part of your lock is fine and points to an electrical issue, most commonly the switch itself or its wiring.
Technical Specifications
OEM Part Numbers: MB791889 MB791892 MB795812 MR714313 MR714314
Varies by part number (Driver/Master vs. Passenger side)
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Mitsubishi Diamante: