P1682 on 1998-2010 RAM 1500 — Ignition 1 Switch Circuit 2
1 vehicles · 1 makes · $100-$400 repair
How to diagnose and fix P1682: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
RAM 1500 · 1998–2010
Rams with the Sentry Key Immobilizer Module (SKIM/WCM) can lock out the fuel injectors if the module fails to read a valid transponder key. The engine cranks, fires for ~2 seconds, then dies, and the security/theft light stays on or blinks. Causes include a failing SKIM/WCM, a damaged antenna ring around the ignition lock, a worn transponder chip in the key, or wiring/connector corrosion.
Common Symptoms
- Engine cranks, starts for ~2 seconds, then stalls
- Security/theft light on solid or blinking
- Intermittent no-start that clears after re-inserting key
- No-start with a worn or non-transponder key
How to Fix
Read the security light while cranking (blinking = SKIM lockout). Diagnose with a scan tool that can access SKIM (basic code readers can't). Fix per cause: reprogram/relearn keys, replace the antenna ring, or replace and re-flash the SKIM/WCM (dealer or locksmith with the PIN). Verify battery/ground first. Typical $100-$400 depending on module vs. key relearn.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Ilco Y160-PT 4D-64 transponder key blank
2002-2005 Dodge Ram 1500 as explicitly listed; must be cut to the vehicle and programmed. With two valid keys, some builds support owner programming; otherwise use a locksmith/dealer.
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Sources for this issue (2)
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P1682 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P1682 mean?
P1682 stands for "Ignition 1 Switch Circuit 2." A manufacturer-specific code used primarily by GM (Chevrolet, GMC, Buick, Cadillac), also listed in GM service data as "Driver 5 Line 2." The engine control module is fed by two separate ignition 1 voltage circuits - one from the ignition switch and one from the run/crank or powertrain relay through a fuse - and P1682 sets when the voltage difference between them exceeds the allowed limit. Because those feeds power the throttle actuator control circuits, this code often accompanies reduced-power mode, a crank-no-start, a no-crank condition, or a stall.
What are the most common causes of P1682?
The most common causes of P1682 are: Failed underhood fuse block / relay center (a very commonly reported cause), Worn or failing ignition switch, Blown fuse or failed run/crank or powertrain relay, Corroded, loose, or damaged ignition-feed connectors, Open or high-resistance wiring in either ignition 1 circuit, Poor ECM ground or corroded ground strap, Faulty engine control module (diagnose last). The specific cause varies by vehicle.
How much does it cost to fix P1682?
Repair costs for P1682 range from $100 to $400, depending on the vehicle and root cause.
Which vehicles are affected by P1682?
Au7o has documented P1682 across 1 vehicle models from 1 manufacturers: RAM.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.