Chevrolet P20 Ignition Switch Guide for 1975-1979 Models
Having trouble starting your P20? The problem might be a simple electrical switch, not a major engine issue.
- A no-start condition on your P20 is often caused by the inexpensive ignition switch, not a major engine problem.
- Symptoms include the engine not cranking, stalling while driving, or accessories failing to work.
- OEM parts are unavailable; reliable aftermarket brands like Standard Ignition and Rostra are the go-to choices.
- This is a DIY-friendly repair, typically requiring you to lower the steering column to access the switch.
Signs of a Failing Ignition Switch
On a workhorse like the P20, electrical parts wear out over time. A failing ignition switch can cause confusing problems that might seem unrelated. Being able to spot the signs can save you from being stranded.
Critical Failure Symptom
If your P20's engine stalls while you are driving, especially when hitting a bump, it could be a faulty ignition switch losing its connection. This is a major safety risk. Pull over immediately and have the ignition system inspected before driving again.
- Engine Won't Crank: You turn the key and nothing happens. The dashboard lights might come on, but the starter motor doesn't make a sound. This can happen when the contacts inside the switch that send power to the starter are worn out.
- Starts and Immediately Stalls: The engine fires up but dies right away. The ignition switch might not be keeping power supplied to the ignition system or fuel pump after the key moves from the 'Start' to the 'On' position.
- Intermittent Starting: Sometimes your P20 starts perfectly, and other times it won't. This unpredictability is a classic sign of an electrical switch beginning to fail. Wiggling the key might sometimes help, pointing directly to a worn switch.
- Accessories Don't Work: If your radio, heater blower, or wipers aren't working, the problem could be the accessory contacts inside the ignition switch.
- Visible Smoke or Melting: In severe cases, a shorted ignition switch can overheat, causing smoke from the steering column or melted wires at the connector. This is a fire hazard and requires immediate attention.
Choosing the Right Aftermarket Ignition Switch
For a vintage vehicle like the 1975-1979 P20, Original Equipment Manufacturer (OEM) parts from Chevrolet are no longer available. The aftermarket is your only source for new ignition switches. Fortunately, reputable brands produce quality replacements.
Brand Quality: Rostra vs. Standard Ignition
When shopping for your P20, you will likely see two main brands: Standard Ignition (SMP) and Rostra Powertrain.
- Standard Ignition: Standard has been a leading name in aftermarket electrical parts for a very long time. They are generally considered a top-tier aftermarket brand, often producing parts that meet or exceed original specifications. For a critical component like an ignition switch, Standard is a reliable choice.
- Rostra Powertrain: Rostra also manufactures a wide range of vehicle electronics and is known for producing direct-fit OE replacement parts. Their switches are engineered with quality materials like copper alloy conductors to ensure good performance and reliability.
Pro Tip: Both Standard and Rostra are solid choices for this part. Given the simplicity of the ignition system on these older trucks, either brand should provide a durable, long-lasting repair. Your decision can confidently be based on price and availability.
Typical Replacement Costs
Replacing the ignition switch on a 1975-1979 P20 is an affordable repair. The parts themselves are not expensive, and the labor is straightforward for a mechanic familiar with older GM trucks.
| Part/Service | Estimated Cost |
|---|---|
| New Aftermarket Ignition Switch | $20 - $55 |
| Shop Labor | $90 - $180 |
| Total Estimated Cost | $110 - $235 |
Frequently Asked Questions (FAQ)
Is the ignition switch the same as the ignition lock cylinder?
No. The lock cylinder is the mechanical tumbler assembly that your key fits into. The ignition switch is the separate electrical part that the lock cylinder turns, often via a connecting rod inside the steering column. If your key is stuck or won't turn, the lock cylinder is likely the problem. If the key turns fine but the truck won't start or power on correctly, the ignition switch is the more probable cause.
Can I replace the ignition switch myself?
Yes, this is a DIY-feasible job for someone with basic mechanical skills. The switch is typically mounted on top of the steering column, under the dashboard. The process involves lowering the steering column for access, disconnecting the electrical plugs, removing two screws holding the switch, and installing the new one. No highly specialized tools are required, just basic hand tools like sockets and screwdrivers.
Do I need to check for recalls on my P20's ignition switch?
No. A search of the National Highway Traffic Safety Administration (NHTSA) database shows no recalls or technical service bulletins (TSBs) specifically for the ignition switch on the 1975-1979 Chevrolet P20. This is common for a vehicle of this age.
Could a bad ignition switch drain my battery?
Yes. If the switch fails to completely shut off all accessory circuits when the key is turned to the 'Off' position, it can create a slow power drain that leaves you with a dead battery. If you're experiencing a dead battery after the truck sits for a day or two, a faulty ignition switch could be the cause.
Technical Specifications
The ignition switch for this vehicle is a rod-actuated electrical switch mounted on the steering column, separate from the key lock cylinder. It typically has multiple electrical terminals to control the starter, ignition, and accessory circuits.
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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.