Chevrolet P20 Back Up Light Switch: A Guide for 1975-1989 Models
Fix your P20's reverse lights by finding the right switch, whether it's on your steering column or transmission.
- First, identify your transmission. Automatics use a Neutral Safety Switch on the steering column; manuals use a dedicated switch on the transmission case.
- Symptoms include no reverse lights, lights stuck on, or (on automatics) a no-start condition.
- Aftermarket is the only option. Brands like Standard Ignition are a trusted choice for this repair.
- If you have an automatic, the new switch MUST be adjusted after installation to ensure proper starting and light function.
Is It the Back Up Light Switch or the Neutral Safety Switch?
The most common point of confusion for 1975-1989 Chevrolet P20 owners is the location of the back up light switch. Before ordering a part, you must know which transmission you have.
- Automatic Transmission: If you have a column-shifted automatic (like a TH350 or TH400), your back up lights are controlled by the Neutral Safety Switch (NSS). This part is located on the steering column, usually high up under the dashboard. It serves two functions: allowing the engine to crank only in Park or Neutral, and activating the reverse lights when you shift into Reverse. Problems with this switch can cause both starting issues and reverse light failures.
- Manual Transmission: If you have a manual transmission (like an SM465), your back up light switch is a simpler, single-purpose switch. It screws directly into the side of the transmission case and is activated internally when you shift into reverse gear.
Symptoms of a Failing Back Up Light Switch
A bad switch can create unsafe driving conditions. Look out for these common signs of failure:
- No Reverse Lights: The most common symptom is that the lights simply don't turn on when you shift into reverse. Always check the bulbs and fuses first before replacing the switch.
- Reverse Lights Stay On: The switch can fail in the 'on' position, leaving the reverse lights illuminated at all times. This can drain your battery and confuse other drivers.
- Intermittent Lights: The lights may flicker or only work sometimes. This often points to worn internal contacts in the switch.
- No-Start Condition (Automatics Only): If your P20 has an automatic transmission and won't crank, the Neutral Safety Switch is a primary suspect. You might also find it starts in Neutral but not Park, or you have to jiggle the shifter to get it to start.
A Note on Safety
Driving without functional reverse lights is illegal in many places and is a significant safety hazard. Other drivers and pedestrians will not have a clear visual warning that your vehicle is backing up. Address this issue promptly.
Choosing the Right Aftermarket Back Up Light Switch
For a vehicle of this age, new Original Equipment (OEM) parts from GM are generally not available. Aftermarket parts are the standard solution. The quality of aftermarket switches is typically very good and reliable for the P20.
Two common brands you will find are:
- Standard Ignition (Standard Motor Products): SMP is a well-respected brand that has been trusted by professional mechanics for decades. Their parts are known to meet or exceed original specifications and are a solid choice for reliability.
- Rostra Powertrain: Rostra is a large manufacturer of automotive electronic components for both OEM and aftermarket applications. They are a known supplier in the industry and offer a viable alternative for this part.
For a critical safety component on a work vehicle, spending a few extra dollars on a reputable brand like Standard Ignition is a wise investment in reliability and peace of mind.
Cost of Replacing a Chevrolet P20 Back Up Light Switch
| Part/Service | Estimated Cost |
|---|---|
| New Aftermarket Switch | $16.17 - $53.37 |
| Shop Labor | $60 - $180 |
| Total Estimated Cost | $76 - $234 |
Frequently Asked Questions (FAQ)
Is replacing the back up light switch a DIY job?
Yes, for many owners. If you have an automatic, the switch is on the steering column and is accessible from inside the cab. It's held by two screws and requires careful adjustment. If you have a manual, the switch is on the transmission. Access can be tight, and on trucks without a removable transmission tunnel, it can be challenging to reach.
Does the new switch need to be adjusted?
Yes, if you have an automatic transmission. The Neutral Safety Switch on the steering column has slotted mounting holes. After installing the new switch, you must adjust its position to ensure the engine only starts in Park/Neutral and the reverse lights only come on in Reverse before you fully tighten the screws.
Can I just bypass the switch?
While it is physically possible, it is strongly discouraged. Bypassing the Neutral Safety Switch on an automatic creates a major safety hazard, allowing the vehicle to start in any gear. Bypassing a faulty switch for the reverse lights is also not recommended, as it's a simple and inexpensive part to replace correctly.
My new switch didn't fix the problem. What now?
If a new switch doesn't solve your reverse light issue, go back to the basics. Check that you have the correct bulbs and that they aren't burned out. Test the fuse for the back up light circuit. Finally, inspect the wiring and bulb sockets for any corrosion, breaks, or bad grounds, which are common on older vehicles.
Are there any recalls for the P20 back up light switch?
No. Searches of the National Highway Traffic Safety Administration (NHTSA) database do not show any recalls or technical service bulletins (TSBs) for the back up light switch or neutral safety switch on the 1975-1989 Chevrolet P20.
Technical Specifications
OEM Part Numbers: 1994212
Varies by transmission type. Automatic transmission models use a multi-function switch on the steering column. Manual transmission models use a two-terminal switch on the transmission case.
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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.