1990 Infiniti Q45 Air Bag Module: Resetting the Light & Replacement Guide

Key Symptoms of a Failing Air Bag Module

The most common and often only symptom of a problem with the airbag system is the red 'SRS' or airbag warning light on the instrument cluster. For the 1990 Q45, this can present in two ways:

• Flashing Airbag Light: A constantly flashing light often means the system has been put into a self-diagnosis mode, which can sometimes happen by accident. It may not indicate an actual fault with a part. This guide will show you how to reset this mode below.
• Solid (Non-Flashing) Airbag Light: If the light comes on and stays on solid after the initial startup check, or if it remains on after performing a reset procedure, it indicates a definite fault in the SRS system. This could be the module itself, an impact sensor, the airbag clockspring, or wiring.

Diagnosing and Resetting the Airbag Light

The 1990 Infiniti Q45 uses an early, pre-OBD-II diagnostic system. You do not need a modern scan tool to check or reset the light. The system uses the driver's side door switch to enter and exit diagnostic modes.

How to Reset the Flashing Airbag Light

If your airbag light is just flashing, it may simply be in diagnostic mode. Follow this procedure to return it to user mode:

1. Open the driver's side door and leave it open.
2. Turn the ignition key to the 'ON' position (do not start the engine). The airbag light will be on.
3. Within about 10 seconds, press and release the driver's side door jamb switch (the black rubber-covered button that the door presses when it closes) at least 10 times.
4. If the procedure was successful, the flashing light will turn off. If the light stays on solid, it means there is a hard fault in the system that needs to be repaired.

If the light indicates a hard fault, the module may have stored a diagnostic code. While a full code chart for this specific model is not readily available, the flashing pattern itself can indicate the nature of the problem to a technician with an appropriate service manual.

Known Issues and Common Failure Modes

Internal Capacitor Failure

Like many automotive electronics from the 1990s, the airbag control module is susceptible to failure from aging internal components. The most common culprits are electrolytic capacitors. Over decades, these components can leak their electrolytic fluid, which is corrosive and can damage the circuit board, or they can simply dry out and fail to hold a charge. This is a very common reason for a module to fail its internal self-test and trigger the airbag light.

Crash Data Lock

If the vehicle has been in an accident where the airbag was deployed, the module stores permanent 'crash data' and locks itself. This is a safety feature to ensure the system is fully inspected after a collision. A locked module cannot be reset through normal procedures and will keep the airbag light on. It must be replaced or sent to a specialist service to have the crash data professionally cleared from its internal memory chip (EEPROM).

Buying a Used 1990 Q45 Air Bag Control Module

Since new OEM modules are no longer available, a quality used OEM module is the most practical solution. Here is what to look for to ensure you get a good part:

• Verify Part Numbers: Ensure the part number on the replacement module exactly matches your original one. The most common part number is 28555-60U00. The number B8555-F60U00 may also be found, which typically indicates a factory-remanufactured part.
• Ask About Crash History: This is the most important question. Ask the seller directly if the module was removed from a vehicle that had its airbags deployed. A module with crash data stored is not a plug-and-play part and will require a costly reset service.
• Physical Inspection for Capacitor Leakage: If possible, ask the seller for clear pictures of the internal circuit board, or inspect it yourself upon receipt. Look for small, cylinder-shaped capacitors. Check their tops to see if they are bulging or leaking a crusty, brownish residue. Any sign of leakage means the module is bad or will fail soon.
• Check for Water Damage: The module is typically located in the center console area. Look for any signs of corrosion or water marks on the outer case or internal board, which can indicate damage from spills or leaks.

Programming and Setup After Installation

No programming is required. The 1990 Infiniti Q45 airbag control module is a self-contained unit. It does not need to be programmed, flashed, or coded to the vehicle's VIN. As long as you install a compatible, functional module that is clear of crash data, it will be plug-and-play. After installation, you may need to perform the door switch reset procedure described above to clear any codes stored during the replacement process.

Cost to Replace a 1990 Q45 Air Bag Module

Replacing the airbag module is a straightforward but delicate job. Always disconnect the battery before working on any airbag components.

Frequently Asked Questions (FAQ)