P1682 is a diagnostic trouble code that indicates that the ignition switch is having a voltage problem. It is typically caused by a faulty ignition switch.
There are two “circuits” to the ignition system. The first one goes to the ECM through the throttle actuator control. The second ignition voltage circuit (the one in question) goes through the ignition switch.
P1682 Affected Makes
This article is meant to help with diagnosing P1682 in vehicles manufactured by General Motors such as:
- Buick
- Cadillac
- Chevrolet
- GMC
- Hummer
- Isuzu
- Oldsmobile
- Pontiac
- Saturn
P1682 Symptoms: GM Vehicles
The only symptom that you should experience with P1682 is the vehicle not starting. The check engine light will be on as well.
P1682 Causes
Here are the most common causes of P1682:
Ignition Switch
A bad ignition switch is the most common reason that P1682 will occur. You’re going to need to test it before you replace it. It’s a pretty straightforward process. Here’s an article that covers everything that you would need to know about testing it.
Fuse Block
As the fuse block expands and contracts, it can eventually cause a hairline crack in the wire that runs from the ignition. A good sign that this is the problem is when the vehicle won’t start when the engine is hot, but it will once it cools all the way off. Here is a fantastic video that covers this scenario.
This is particularly common on the Chevy Trailblazer, GMC Envoy, and Chevy SSR. They all use a fuse block that is known to do this.
ECM
The ECM should be last on the list. It is possible a bad ECM could be the cause. At this point, it would be wise to take it in to a mechanic that is skilled in diagnosing a bad ECM.
Conclusion: P1682
Good luck diagnosing P1682 in your GM made vehicle. If there is anything that you would like to add, please leave a comment below. Thank you!