Tech Tip: Diagnosing Lit ‘Low Tire’ Lamp on Mercury Mariner Hybrid – UnderhoodService

Tech Tip: Diagnosing Lit ‘Low Tire’ Lamp on Mercury Mariner Hybrid

Vehicles with a tire pressure monitoring system (TPMS) may display a solid TPMS indicator, and the message center (if equipped) may display "Low Tire Pressure." This may result from the actual tire pressure being low due to time or temperature changes (10° F = 1 psi). Adjusting the tire pressure to specification should turn out the warning light once the sensors have been awakened ....

Mr. Ellis called first thing this morning to ask why the “low tire” lamp was on in his 2006 Mercury Mariner Hybrid. He needed to get out to the golf course for an 8 a.m. tee time. I told him that as long as the tire wasn’t flat, to come over to the shop and I would check the tire pressure. I guessed that cold weather combined with low tire pressure may be causing the lamp to illuminate. A quick check showed that the left rear tire was 5 psi below specification. After adding some air, Mr. Ellis was on his way to the country club.

Vehicles with a tire pressure monitoring system (TPMS) may display a solid TPMS indicator, and the message center (if equipped) may display “Low Tire Pressure.” This may result from the actual tire pressure being low due to time or temperature changes (10° F = 1 psi). Adjusting the tire pressure to specification should turn out the warning light once the sensors have been awakened.

If the vehicle has been stationary for more than 30 minutes, it will be necessary to wake up the sensors with the training tool, forcing them to transmit the latest air pressure information to the smart junction box (SJB), or responsible module. This can be done by either driving the vehicle for two minutes above 20 mph or by using the training tool. The sensors do not continuously transmit when the vehicle is not moving.

Rotunda P/N 204-324 (for valve-mounted sensors) or 204-363 (for wheel-mounted sensors) Tire Pressure Monitor Activation Tool or equivalents may be required to perform the wake-up procedure.

Applicable Vehicles:
• 2003-’06 Expedition, Explorer
• 2006 Escape Hybrid, Escape, Freestar
• 2003-’05 Aviator
• 2003-’06 Navigator
• 2003-’06 Mountaineer
• 2006 Mariner Hybrid, Mariner, Monterey

Repair Procedure:
1. Inflate all tires to the correct air pressure.

2. Place the ignition in the RUN position.

3. Use the correct special service tool for valve- or wheel-mounted sensors.

4. Place the magnet on each sensor for approximately five seconds or ping each sensor at least twice after adding air to ensure the module has the latest air pressure data.

5. If the TPMS indicator does not go off after filling the tires to the correct air pressure and pinging each sensor then refer to Tire Monitoring System in your repair information system for further diagnosis.

Courtesy of ALLDATA Technical Editor Eric Seifert, an ASE certified Master Technician and Engine Machinist, with 20 years of independent shop and parts store experience.

For additional information on ALLDATA, visit www.alldata.com.

You May Also Like

EV Opportunities

You are gaining and retaining many service opportunities with Evs.

You are wrong if you think that the electric vehicle will be the end of the independent shop. You might be losing spark plugs, air filters and timing chains. But, you are gaining and retaining many service opportunities.

Even a Tesla has a 12-volt battery used to power a number of systems on the vehicle like the ABS, lighting and power steering. These are typically AGM batteries in conventional sizes.

Caring For AGM And Flooded Car Batteries

Faulty battery cables, if loose, corroded, or damaged, can lead to power drainage.

Selling Underhood Parts for Hybrids

Anything that can happen to an ICE in a standard vehicle can happen in a hybrid.

Hyundai & Kia Hybrid Drivetrain

The Hyundai hybrid system has a motor control unit (MCU) and hybrid control unit (HCU).

EV Charging Systems

For an electric vehicle to recharge rapidly, it requires more power, and in a different format.

Other Posts

Ford EV Opportunities

Despite what you may imagine, there are still maintenance and repair opportunities in a Ford Mustang Mach-E.

Jump Starting an EV

If an EV with a full battery won’t start, here’s how you can get it up and running.

Five Technology Trends that Will Define the Future of EVs

IDTechEx says it believes Li-ion is forecast to maintain its dominant position.

HV/EV Lifting Guidelines

Being able to lift an EV or HEV vehicle properly is a roadblock many shops face.