Infiniti Q45 (1990-2006) Brake Light Switch Guide
Solve common brake light and cruise control issues by choosing the right replacement brake light switch for your Q45.
- A failing brake light switch is a critical safety issue and should be replaced immediately.
- Symptoms are not just limited to lights; a bad switch is a common cause of cruise control failure on the Q45.
- A small recall was issued for some 2004 models for a faulty switch, confirming this as a known issue.
- Before replacing the switch, check the small plastic stopper on the pedal arm, as its failure causes similar symptoms.
Symptoms of a Failing Brake Light Switch
A bad brake light switch on a Q45 can cause several confusing problems. Because the switch is involved in more than just the lights, a failure can affect other systems. Before assuming the switch is bad, always check the simple things first, like the brake light bulbs and fuses.
- Brake Lights Don't Work: The most obvious and dangerous symptom. The switch fails to complete the circuit, and your brake lights will not illuminate at all.
- Brake Lights Stay On: The switch can get stuck in the 'on' position, leaving your brake lights permanently lit. This will drain your battery and confuse other drivers.
- Cruise Control Won't Set: If the switch is faulty, the cruise control system may think the brakes are being applied, preventing you from setting a speed. This is a very common issue reported by owners.
- Can't Shift Out of Park: A failed switch may prevent the shift interlock from disengaging, trapping your gear selector in 'Park'. 🎬 Watch: How to fix an Infiniti shifter stuck in park.
Recall on 2004 Infiniti Q45
Infiniti issued a small but important safety recall for a handful of 2004 Q45 models (NHTSA Campaign ID: 04V497000). The recall addressed a brake lamp switch that could malfunction and prevent the brake lights from turning on. Only 55 vehicles were affected, but it confirms a potential point of failure for this part. The replacement part number cited in the recall was 25320-4M400.
Choosing the Right Aftermarket Brake Light Switch
For a part like a brake light switch, you don't always need to buy from the dealer. Many aftermarket brands offer excellent quality, and some even supply the original parts to Infiniti. Here’s how the available brands generally stack up based on user reviews and industry reputation.
Premium Aftermarket (Good Bet)
These brands are known for quality and are often considered equivalent to original equipment.
- Beck Arnley: Often sources parts directly from the same manufacturers that supply Infiniti. For Japanese vehicles, this brand is widely trusted to be a direct, high-quality replacement.
- Standard Ignition (SMP): A long-standing, reputable manufacturer of automotive electrical components with a solid track record.
Standard Aftermarket (Reliable Value)
These brands are a good balance of price and quality for most repairs.
- Dorman: Offers a wide range of parts, but quality can sometimes be inconsistent according to some mechanics and vehicle owners.
- Facet, Holstein, Vemo: European brands with a reputation for producing reliable electronic components.
Economy Brands (Budget-Friendly)
These are your most affordable options, suitable for a tight budget, but may not have the same long-term durability as premium brands.
- URO Parts, True Tech, Replacement: These brands focus on providing a low-cost alternative. They can be a good choice, but inspect the part for quality before installation.
Check the Pedal Bumper/Stopper
On the brake pedal arm, there is a small plastic or rubber stopper that presses the switch's plunger. Over time, these stoppers can become brittle and break, falling to the floor mat. If this happens, the switch plunger will no longer be pressed when the pedal is at rest, causing the brake lights to stay on. Always check that this stopper is intact before replacing the switch itself.
🎬 See how to replace a broken brake pedal stopper.Cost of a New Brake Light Switch (1990-2006 Infiniti Q45)
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket | $6.28 - $67.91 |
| New OEM (Dealer) | $45 - $70 |
| Shop Labor | $50 - $100 |
Frequently Asked Questions
Can I replace the brake light switch myself?
Yes, this is a very DIY-friendly repair. The switch is located on the brake pedal assembly under the dashboard. It usually requires unplugging an electrical connector and unscrewing the switch. The main difficulty is the uncomfortable position required to access it in the driver's footwell.
Why did my cruise control stop working when the brake light switch failed?
The brake light switch sends a signal to disengage the cruise control when you press the brake pedal. If the switch fails, it might send a constant 'off' signal to the cruise control module, preventing it from ever engaging. 🎬 Watch this quick fix if your cruise control won't engage. Some Q45 models may have a separate, second switch on the pedal assembly just for the cruise control.
Do I need to adjust the new switch?
Yes, proper adjustment is critical. The new switch must be threaded in so that its plunger is fully depressed when the brake pedal is at rest, but is released immediately when you begin to press the pedal. Incorrect adjustment can cause the brake lights to stay on, not come on, or prevent the cruise control from working.
Is there a difference between the switch for early and late model Q45s?
Yes, part numbers can vary across the Q45's long production run (1990-2006). For example, the part number for the 2004 model recall was 25320-4M400. Always verify the correct part for your specific model year before purchasing to ensure proper fit and function.
Helpful Videos
Technical Specifications
OEM Part Numbers: 25320-4M400
The brake light switch for the Infiniti Q45 is a plunger-style switch located on the brake pedal assembly. It typically features a 2-pin or 4-pin electrical connector, depending on the year and whether it integrates cruise control functions. Part number 25320-4M400 is a common replacement for later models, but part numbers may differ for earlier generations (1990-2001). Always verify the part number for your specific vehicle year.
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.
- INFINITI Q45:
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- Symptoms of a Failing Brake Light Switch
- Recall on 2004 Infiniti Q45
- Choosing the Right Aftermarket Brake Light Switch
- Premium Aftermarket (Good Bet)
- Standard Aftermarket (Reliable Value)
- Economy Brands (Budget-Friendly)
- Check the Pedal Bumper/Stopper
- Cost of a New Brake Light Switch (1990-2006 Infiniti Q45)
- Frequently Asked Questions
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