1970-1981 GMC Jimmy Back Up Light Switch: A Complete Guide
Everything a Jimmy owner needs to know about diagnosing and replacing a faulty back up light switch.
- The most common failure is simply no reverse lights.
- Confirm if you have an automatic or manual transmission before ordering, as the parts are different.
- A simple 'jumper wire' test can confirm if the switch is the faulty component.
- Reputable aftermarket brands like Standard Ignition are reliable replacements for the unavailable OEM part.
Is Your Back Up Light Switch Failing?
A bad back up light switch on these classic Jimmys usually fails in a few predictable ways. Because the electrical systems are straightforward, diagnosis is typically simple. The most common issue is simply no reverse lights at all when you shift into reverse. You might also see them flicker or only work when you jiggle the shifter, which points to a worn or misaligned switch. In some cases, an internal short in the switch can repeatedly blow the fuse, which is often shared with the turn signals and labeled "TURN B/U".
Choosing the Right Aftermarket Switch
For a vehicle from this era, finding a new original GM part is nearly impossible. The market is served by quality aftermarket manufacturers who specialize in creating parts that meet or exceed the original design. You don't need to worry about a drop in quality compared to a 40+ year-old original part.
Your main choice will be between different aftermarket brands. The key is choosing a reputable one.
- Standard Ignition (SMP): A very well-known and respected brand in the industry. They often promote their use of quality materials like copper conductors and 100% testing of their switches. For many professional mechanics, Standard is a go-to for reliable, OE-fit electrical parts.
- Rostra Powertrain: Rostra is another established manufacturer, known for transmission and powertrain electronics. While maybe less of a household name than Standard for general repairs, they are a significant player in the parts world and produce a wide range of switches and sensors.
Pro Tip: Automatic vs. Manual
The most common ordering mistake is getting the wrong switch for your transmission. A switch for an automatic column-shift Jimmy is completely different from a switch for a 4-speed manual. Always verify your transmission type before ordering.
Typical Replacement Costs
Replacing the back up light switch is an affordable repair. The parts themselves are inexpensive, and labor is minimal for an experienced mechanic.
| Item | Estimated Cost |
|---|---|
| New Aftermarket Part | $16 - $41 |
| Shop Labor | $50 - $100 |
| Total Estimated Cost | $66 - $141 |
Frequently Asked Questions
Where is the back up light switch located on my Jimmy?
It depends on your transmission. If you have an automatic with a column shifter, look for it at the base of the steering column, down by the firewall inside the cab. If you have a manual 4-speed transmission, it's a screw-in sensor on the side of the transmission case itself, under the truck.
How do I know if the switch is bad, and not the bulbs or wiring?
First, check the bulbs and the fuse. If those are good, you can test the switch. A common method is to access the switch's electrical connector, unplug it, and use a small piece of wire to jump the two terminals in the connector. If the reverse lights turn on, the wiring and bulbs are good, and the switch is the problem.
Are there any recalls for this part?
No. Searches of the National Highway Traffic Safety Administration (NHTSA) database show no recalls or safety campaigns for the back up light switch on the 1970-1981 GMC Jimmy.
Is this a difficult part to replace myself?
For most DIY mechanics, this is a very feasible job. It requires basic hand tools. The biggest challenge is usually access, as the switch on the column is under the dash and the one on the transmission can be in a tight spot. Disconnecting the battery is always recommended before starting any electrical work.
Technical Specifications
The key specification is the transmission type (automatic or manual). Automatic transmission switches are typically mounted on the steering column. Manual transmission switches are screw-in types located on the transmission housing.
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.