GMC P3500 Back Up Light Switch Guide for 1979-1981 Models
Solve reverse light problems on your P3500 by understanding and choosing the correct new back up light switch.
- Verify if your truck has an automatic or manual transmission before ordering; they use different switches.
- The switch is on the steering column for automatics and on the transmission for manuals.
- Always check the fuse and bulbs before assuming the switch has failed.
- Standard Ignition is a reputable aftermarket brand for this part.
Is Your P3500 Back Up Light Switch Failing?
A faulty back up light switch is a common issue on older trucks like the GMC P3500. Failure can be a safety hazard and may get you a ticket. Before you replace the switch, always check the simple things first: the fuse (often labeled 'TURN B/U') and the reverse light bulbs themselves. If those are good, the switch is the next logical part to inspect.
Pro Tip: Automatic vs. Manual Transmission
The most common ordering mistake is getting the wrong switch for your transmission. Automatic transmission models use a combination Neutral Safety/Back Up Light switch on the steering column. Manual transmission models use a simpler switch on the transmission case. You must identify which transmission your truck has before ordering.
Symptoms of a Bad Back Up Light Switch
- Reverse Lights Don’t Work: The most common symptom. When you shift into reverse, the lights do not turn on at all.
- Intermittent Lights: The lights flicker or only work if you wiggle the gear shifter. This often points to a worn or misaligned switch.
- Lights Stay On: The switch can fail in the 'on' position, causing your reverse lights to stay lit continuously, which can confuse other drivers and drain your battery.
Choosing the Right Aftermarket Switch
For a vehicle from this era, new Original Equipment (OEM) parts are generally unavailable. The market relies on quality aftermarket replacements. Brands like Standard Ignition (Standard Motor Products) are well-regarded and produce reliable, direct-fit replacement switches for this application. They are a trusted choice for both professional mechanics and DIY repairs. Given the low cost of the part, choosing a reputable aftermarket brand provides a dependable and affordable solution.
Replacement Cost
Replacing the back up light switch is an affordable repair. The part itself is inexpensive, and labor time is low. Expect to pay more if you have a mechanic perform the work.
| Item | Estimated Cost |
|---|---|
| New Aftermarket Switch | $26.16 - $53.37 |
| Shop Labor | $90 - $150 |
| Total Estimated Cost | $116 - $204 |
Frequently Asked Questions (FAQ)
Where is the back up light switch located?
For an automatic transmission, it is usually part of the neutral safety switch, a half-moon shaped component mounted on the steering column under the dashboard, near the firewall. For a manual transmission, it is a screw-in switch located on the side of the transmission housing itself.
Is this a difficult DIY job?
No, for most people this is an easy DIY repair. For column-mounted switches, the main challenge is working in the tight space of the driver's footwell. For transmission-mounted switches, you will need to safely lift and support the vehicle to gain access. Basic hand tools are all that is required.
Why do I have to wiggle the shifter to get the lights to work?
This usually indicates the switch is either failing internally or has become misaligned. The movement of the shifter completes the connection. While sometimes an adjustment can fix it, it's often a sign that the switch is worn out and needs replacement.
Are there any recalls for the back up light switch on a 1979-1981 GMC P3500?
No. Searches of the National Highway Traffic Safety Administration (NHTSA) database show no recalls or technical service bulletins (TSBs) related to the back up light switch for this specific vehicle.
Technical Specifications
OEM Part Numbers: 14014559 1994212
Varies by transmission type. Automatic transmission switches are typically multi-function (Neutral Safety + Back Up) and mount to the steering column. Manual transmission switches are simple 2-terminal, screw-in units on the transmission case.
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.