P1682: Ignition 1 Switch Circuit 2 (GM)
Key takeaways
- On GM vehicles, P1682 means the engine computer saw its two ignition power inputs disagree, which usually traces to the ignition relay, the underhood fuse block or a battery problem.
- It can cause a reduced engine power message, a stall or an intermittent no-start, so drive short trips only and tow it if it stalls.
- GM bulletins point at the engine controls ignition relay, corroded terminals in the underhood fuse block, and water in a headlamp shorting a circuit.
- 32 owner complaints filed with NHTSA mention P1682, and 15 of them are Chevrolet Traverse, mostly 2014 models.
- P1682 is manufacturer-specific; nearly every bulletin we have is GM, and other makers may define it differently.
What P1682 means
Your engine computer isn’t getting clean, consistent ignition power. On GM vehicles scanners call it “Ignition 1 Switch Circuit 2.” The engine computer is fed switched ignition voltage on more than one circuit, usually through a relay in the underhood fuse block. It compares those inputs; when the second circuit drops out, reads low, or doesn’t match the first, it stores P1682.
P1682 is a manufacturer-specific code. Nearly all of the NHTSA bulletins that name it are from GM brands (Chevrolet, GMC, Buick, Cadillac and Saturn). If you drive another make, check your make’s own definition before acting on this page.
Is it safe to drive?
Short trips only. A weak ignition feed can do nothing noticeable, or it can trigger a reduced engine power message, a stall, or an intermittent crank or no-start. GM bulletins describe all of those with P1682. A stall at speed takes away power steering and brake assist, so stay off the highway until it’s checked.
The answer becomes no if the engine has stalled while driving or keeps dropping into reduced power. Have it towed. If the only sign is a stored code and the car runs normally, it’s still worth fixing soon, because this kind of fault tends to get worse, not better.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Failing engine controls ignition relay | Voltage at the relay output drops or cuts out; code stops after a known-good relay is swapped in | $20–$150 |
| Weak battery or loose, corroded terminals | Battery load test; voltage drop across the terminals and cables | $20–$120 for terminals; $150–$350 for a battery |
| Corroded or arcing terminal in the underhood fuse block | Inspect the fuse block connectors for heat marks, green crust or a loose pin | $100–$250 to repair; $400–$1,000 for a new fuse block |
| Water getting into a connector or headlamp and shorting a circuit | Moisture in the headlamp or its connector; modules stay awake and drain the battery | $100–$250 for wiring, plus the headlamp if it leaks |
| Damaged wiring between the fuse block and the engine computer | Voltage test at the engine computer connector with the key on | $100–$250 |
| A known condition covered by a bulletin (for example P1682 after a MAF sensor replacement on some trucks) | Shop checks bulletins for your VIN | $100–$200 if it is a software fix |
What to check first
- Test the battery and clean the terminals. Cheap, and it removes the most common way a voltage dip gets blamed on something else.
- Check the ignition relay. On GM vehicles it’s in the underhood fuse block; the lid or manual names it. Swapping it with an identical relay for a test is a common first step.
- Inspect the underhood fuse block connectors for corrosion, heat damage or a loose terminal.
- Look for water in the headlamps and connectors, and have a parasitic draw test done if the battery keeps dying.
- Follow the bulletins. The GM pattern is clear: 2013–2017 Traverse, Enclave and Acadia bulletins cover reduced power and stalls with P1682 and P0689, one pointing at arcing or corrosion on a fuse block terminal; 2014–2015 Impala and other Chevrolet bulletins replace the engine controls ignition relay for intermittent crank or no-start; 2016–2019 Silverado and Sierra bulletins cover water in the headlamp causing battery drain and no-start; and 2019–2021 Silverado and Sierra bulletins cover P1682 setting after a MAF sensor replacement.
- Clear it and drive only after the cause is fixed, and watch for it to return.
32 owner complaints filed with NHTSA mention P1682. The Chevrolet Traverse leads with 15, 12 of them 2014 models, followed by the Buick Enclave and GMC Acadia with 3 each. These are owner reports, not confirmed defects.
What it costs
The cheap outcome is a relay or cleaned terminals, $20–$150. The common outcome is a battery at $150–$350 or a fuse block terminal or wiring repair at $100–$250, plus a $100–$180 diagnosis. The expensive outcome is a new underhood fuse block at $400–$1,000. If the car cranks but won’t start today, our cranks but won’t start guide covers the basic checks.
Related codes
On GM vehicles P1682 often comes with P0689 (engine computer power relay sense circuit low) and sometimes with P0101 (MAF sensor performance). P1684 is a neighboring manufacturer-specific code; check its definition for your make rather than assuming it’s related. P0562 points at low system voltage, and other modules may log U0100 if the engine computer drops out entirely.
What owners report to NHTSA
32 complaints filed with NHTSA mention P1682, 29 of them since 2015, across 13 different models. The component owners most often filed it under: electrical system.
Most-reported models
| Vehicle | Complaints | Model years reported |
|---|---|---|
| CHEVROLET TRAVERSE | 15 | 2013, 2014 |
| BUICK ENCLAVE | 3 | 2013, 2014 |
| GMC ACADIA | 3 | 2014 |
Manufacturer service bulletins that name P1682
53 technical service bulletins and manufacturer communications filed with NHTSA mention P1682, from 6 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- CHEVROLET SILVERADO 1500 (2019, 2020, 2021), bulletin 10191214: This technical bulletin provides repair information to correct a customer concern of DTC P0101 Mass Air Flow (MAF) Sensor Performance, P1682 Set after MAF Replacement.
- GMC SIERRA 1500 (2019, 2020, 2021), bulletin 10191214: This technical bulletin provides repair information to correct a customer concern of DTC P0101 Mass Air Flow (MAF) Sensor Performance, P1682 Set after MAF Replacement.
- CADILLAC ESCALADE (2019, 2020), bulletin 10176315: This Preliminary information communicatesSome customers may comment that the SES lamp is illuminated or was Illuminated and turned off. During inspection Technician may notice DTC P1682 (Ignition 1 Switch Circuit 2) acti…
- CHEVROLET SILVERADO 2500 (2019, 2020), bulletin 10176315: This Preliminary information communicatesSome customers may comment that the SES lamp is illuminated or was Illuminated and turned off. During inspection Technician may notice DTC P1682 (Ignition 1 Switch Circuit 2) acti…
- GMC SIERRA 2500 (2019, 2020), bulletin 10176315: This Preliminary information communicatesSome customers may comment that the SES lamp is illuminated or was Illuminated and turned off. During inspection Technician may notice DTC P1682 (Ignition 1 Switch Circuit 2) acti…
- BUICK ENCLAVE (2013, 2014, 2015, 2016), bulletin 10170495: This technical bulletin provides repair information to correct a customer concern of potential reduced engine power message displayed and/or engine stall with DTCs P1682 and/or P0689 Set.
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
What does P1682 mean on a Chevy?
Ignition 1 Switch Circuit 2. The engine computer gets ignition power on more than one input and compares them. When one input drops out or doesn't match, it sets P1682. The usual suspects are the ignition relay, the underhood fuse block and the battery connections.
Can P1682 cause a stall or no-start?
Yes. GM bulletins describe a reduced engine power message, engine stall, and intermittent crank or no-start with P1682. If the engine loses its ignition feed, it can shut off. That's why it's worth fixing even if the car seems fine today.
Can a bad battery cause P1682?
It can contribute. Low voltage or a loose terminal can make the ignition feed dip. GM also has bulletins linking P1682 to battery drain and no-start, where something keeps modules awake with the key off. Test the battery and look for a parasitic draw.
Does P1682 mean the same thing on every car?
No. It's a manufacturer-specific code. All but one of the bulletins we have are from GM brands (Chevrolet, GMC, Buick, Cadillac, Saturn), where it means Ignition 1 Switch Circuit 2. On other makes, use a scan tool that shows the manufacturer's definition.