Water-Damaged Key Fobs & Immobilizer Faults: Chevy Tahoe and GMC Yukon at Lake Granbury

Every summer we run the same call. A Tahoe or a Yukon is parked at a ramp on Lake Granbury, the family is loading up, and a fob goes into the water — off a dock, out of a swim trunk pocket, or into the bilge of a boat that gets pulled out three hours later. Call or text (817) 214-2934 and we will bring a working key to the ramp.

Quick Answer

A key fob that has been in lake water is usually not recoverable, and the faster you accept that, the faster you are driving again. In Granbury, replacement fob supply and programming for a Chevrolet Tahoe or GMC Yukon typically runs $150–$350 as of July 2026, done on site in under an hour. If the SUV also has a security light and a no-start after water exposure, that is a separate and less common problem — a body control module or immobilizer fault, quoted at $120–$500 depending on what the scan shows.

What Actually Happens Inside a Soaked Fob

People assume a wet fob either works or does not. The failure is more gradual and more annoying than that.

Immediate short circuit. Lake water is not distilled. It carries dissolved minerals and organics that conduct electricity. When it bridges circuit traces with the battery still installed, current flows where it should not. That is the moment most of the damage happens — not later while it dries.

Corrosion after the fact. Even a fob that seems fine the next morning has mineral residue on the board. Over the following weeks, corrosion creeps across solder joints and contact pads. This produces the classic pattern: the fob works, then works intermittently, then works only when held right against the start button, then stops.

Swollen or leaking battery. Coin cells do not like being submerged. A corroded battery contact will produce symptoms identical to a failed fob.

Button membrane failure. The rubber pad and its carbon contacts degrade after water intrusion, so lock and unlock buttons stop responding while passive entry still works, or vice versa.

If your fob went in the water and you want a chance at saving it: pull the battery immediately, do not press any buttons, open the case, and let it dry thoroughly. Rice does nothing useful. Even done perfectly this is a coin flip, and the honest advice is to get a replacement programmed rather than gamble a lake weekend on a dried-out board.

Is It the Fob, or Is It the Truck?

This is the distinction that decides whether your bill is a fob or a diagnostic job.

Points to the fob

• Only one of your two fobs misbehaves.
• Buttons work but passive entry does not, or the reverse.
• Symptoms started right after a water event.
• Holding the fob directly against the start button lets the SUV start — that backup path proves the vehicle side is fine and the fob's transmitter is weak.

Points to the vehicle

• Both fobs fail simultaneously.
• Security or anti-theft light is illuminated or flashing.
• The engine cranks and starts, then immediately dies.
• Door locks, interior lighting, or remote start behave erratically in ways unrelated to the fob.

That second list points at the body control module or the keyless-entry system rather than the key. On full-size GM SUVs the body control module is the hub for a great deal of vehicle behavior, and it is not a part that enjoys water intrusion — which does happen on SUVs used hard around ramps and low water crossings. See our immobilizer programming service for how that side of the work is handled.

Granbury Pricing

Hood County ranges as of July 2026, exact price quoted by VIN before dispatch. Dealer pricing for comparable key work commonly starts at $200–$600 and requires the vehicle at their service drive — our mobile pricing typically lands 40–60% below that.

The Lake Granbury Pattern

Roughly 8,000 surface acres of water with public ramps, private docks, and a lot of Hood County families who spend weekends on it. That produces a fob-loss pattern we see nowhere else in our service area.

Ramps. The moment of highest risk is loading and unloading, when keys are in a pocket, being handed between people, or set on a gunwale. Water on the ramp is shallow, murky, and full of rock — a dropped fob is often visible and still unrecoverable.

Docks. The gap between a dock board and the water swallows a fob permanently. Retrieval is not realistic.

Swimming. A fob in a pocket that goes off a dock or a boat has usually been submerged for minutes, not seconds. That is a different exposure than a splash.

Low water crossings. Rural Hood County roads flood fast. A soaked interior after a crossing can put water into places the key system does not tolerate, which is when the conversation shifts from fob to vehicle module.

Practical prevention that actually works: a floating key lanyard for lake days, and a second fob that stays at the house rather than in the same bag as the first. Neither costs much, and both are cheaper than an emergency call at the ramp.

How We Handle a Ramp Call

1. Verify ownership. Registration, title, or insurance matching your photo ID. Texas locksmiths operate under the Texas Department of Public Safety Private Security Program, and this step is required, not discretionary.
2. Get you into the vehicle if needed. If the SUV is locked with the only fob at the bottom of the lake, that is a lockout followed by a key job. Our car lockout service covers damage-free entry.
3. Confirm the system. Year and trim, whether the SUV uses push-button start or a key slot, and how many fobs currently exist.
4. Supply the correct fob. Part families vary by model year and equipment. The wrong fob will not pair regardless of tooling.
5. Cut the emergency blade from VIN data so the mechanical door backup works.
6. Pair and test. Lock, unlock, passive entry at each door, remote start if equipped, engine start, and the dead-battery backup procedure. Where the SUV's security gateway requires credentialed access, that runs through the NASTF Vehicle Security Professional system.

Common Tahoe and Yukon Symptoms We See

Fob works only when held against the start button

The vehicle's designed backup for a dead or weak fob battery. It confirms the vehicle side is healthy. Replace the battery first — if that does not fix it, the transmitter is damaged.

Passive entry dead, buttons alive

Water damage frequently takes out one function and not the other because they use different parts of the circuit. It is a real failure even though the fob "still works."

Both fobs stopped after a flooded crossing

Two fobs failing at once almost never means two fobs failed. Look at the vehicle — the receiver, the body control module, or a wet connector.

Security light on, starts and stalls

Immobilizer refusal. The engine authenticates for a moment and is shut down. This is a diagnostic job, not a fob purchase.

The fob "came back" after drying, then died a month later

The corrosion timeline described above. This is the most common reason people end up paying for an emergency call after they thought they got away with it.

The Honest Boundary

We do not repair water-damaged circuit boards, and we are skeptical of anyone who claims to reliably. Cleaning corrosion off a consumer-grade fob board is a temporary result at best, and a fob that fails again at a boat ramp in August has cost you far more than the replacement would have.

Likewise, if the scan points to a failed body control module rather than a key problem, that is a different scope of work and possibly a dealer job depending on the model year and what access the module requires. We tell you which one you have and we do not sell you a fob to fix a module.

Related Reading and Services

• Key fob replacement in Granbury — the service page for all makes
• Transponder key vs smart key vs key fob — which one your vehicle actually uses
• Locked keys in the car at the lake — the lockout side of the same weekend
• Emergency car key replacement in Granbury — what to have ready when you call
• Chevrolet key replacement — brand page for Tahoe, Suburban, and Silverado owners

Frequently Asked Questions

My key fob fell in Lake Granbury. Can it be saved? Occasionally, if it comes out within seconds, the battery is pulled immediately, and it is opened and dried thoroughly. Most cannot. Even fobs that seem to recover often fail weeks later from corrosion, which is why we recommend replacing rather than gambling.

How much does a replacement Tahoe or Yukon fob cost in Granbury? As of July 2026, fob supply and programming typically runs $150–$350 in Hood County depending on the fob your model year requires. We quote the exact figure by VIN before we dispatch.

Can you come to a boat ramp or a dock? Yes. Ramps, marinas, lake houses, and roadside are normal calls for us. Give us the ramp name or a cross street and we will find you.

Both of my fobs quit at the same time. Is that water damage? Probably not to the fobs. Two simultaneous failures usually point at the vehicle — the receiver, the body control module, or a wet connector. That is a diagnostic job before it is a parts purchase.

Does putting a wet fob in rice work? No. Rice does not draw moisture out of a sealed electronic assembly in any meaningful way. Pulling the battery immediately and opening the case to air-dry is far more effective, and still no guarantee.

Will a cheap fob from an online seller work if you program it? Sometimes, and sometimes it will not hold a pairing or will fail within months. We are happy to attempt programming on a customer-supplied fob, but we cannot warranty a part we did not supply, and a failed cheap fob still costs you the service call.

Should I get a spare made now instead of waiting? Yes. A spare programmed while your remaining fob still works is far cheaper than an all-keys-lost call, and it takes under an hour at your home or lake house.

Get a Working Key Back in Your Hand

If a Tahoe or Yukon fob went in the water — or one is behaving strangely after a wet weekend — call or text (817) 214-2934. Serving Granbury, DeCordova, Acton, Pecan Plantation, Tolar, Lipan, Cresson, Glen Rose, and 25 miles out. Weekdays 8:00 AM to 7:00 PM, Saturdays 8:00 AM to 5:00 PM, with 24/7 emergency availability. Or request service through our contact page.

Sources

• National Automotive Service Task Force — Vehicle Security Professional Program
• Texas Department of Public Safety — Private Security Program
• Associated Locksmiths of America
• Texas Parks and Wildlife Department — Boating Safety
• Federal Trade Commission — How to Find a Good Auto Repair Shop