Tire pressure hazard light.

The TPS sensor may be dirty or defective...be sure all tires are above 33 psi...

I found this on another site, it may help to understand what is happening, I also saw that there is a problem with the valve stems cracking since they're made out of aluminum and causing that problem. Here's the explanation provided on another site:

RodneyJ Answered 6 years ago
If a customer with a 2005 or later DaimlerChrysler vehicle equipped with Tire Pressure Monitoring (TPM) is concerned that the TPM lamp is on continuously, please be sure to inform the customer that the system is in place to warn of a low tire pressure situation, and a system diagnosis may not be required. The customer should be aware of the following: The Tire Pressure Monitoring (TPM) System will warn the driver of a low tire pressure based on the vehicle recommended cold placard pressure (the placard is located on the drivers side B-pillar).
The tire pressure will vary with temperature by about 6.9 kPa (1 psi) for every 6.5 Degrees C (12 Degrees F). This means that when the outside temperature decreases, the tire pressure will decrease - the customer should adjust his tire pressure for this decrease in pressure - please refer the customer to his vehicle owner's manual for information on how to properly inflate his vehicle's tires. The tire pressure will also increase as the vehicle is driven - this is normal and there should be no adjustment for this increased pressure.
The TPM System will warn the driver of a low tire pressure if the tire pressure falls below the low pressure warning threshold for any reason, including low temperature effects.
The TPM System will continue to warn the driver of low tire pressure as long as the condition exists, and will not turn off until the tire pressure is at or above recommended cold placard pressure. Once the low tire pressure warning has been illuminated, the tire pressure must be increased to the recommended cold placard pressure in order for the TPM warning lamp to be turned off. The system will automatically update and the TPM warning lamp will extinguish once the updated tire pressures have been received. The vehicle may need to be driven for up to 10 minutes above 25 kph (15 mph) to receive this information.


FOR EXAMPLE:

A 2006 300 has a recommended cold (parked for more than 3 hours) placard of 207 kPa (30 psi).

If the ambient temperature is 18 Degrees C (65 Degrees F) and the measured tire pressure is 186 kPa (27 psi) the TPM lamp will be OFF.

IF NOTHING IS DONE TO THE AIR PRESSURE IN THE TIRES and the ambient temperature drops to 20 Degrees F (-7 Degrees C) while the vehicle is parked, the approximate tire pressure will be 157 kPa (23 psi) and the TPM lamp will be ON.

IF THE VEHICLE IS DRIVEN TO REACH NORMAL OPERATING TEMPERATURE

WITHOUT ADJUSTING THE AIR PRESSURE and the ambient temperature stays at -7 Degrees C (20 Degrees F), the approximate tire pressure will rise to 186 kPa (27 psi) and the 1PM lamp will be ON.

To turn the TPM lamp OFF the tires must be inflated to the vehicle recommended cold placard pressure.

In order to properly maintain vehicle tire pressure, please refer to the owner's manual for additional information regarding tire inflation.

NOTE :Tire pressure should always be set based on cold inflation tire pressure (defined as the tire pressure after a vehicle has not been driven for more than 3 hours - and in outside ambient temperature).

Seasonal temperature changes will affect tire pressure, and the TPM system will monitor the actual tire pressure in the tire.
If a diagnosis of the system is required (for example, the lamp did not extinguish, or the lamp is flashing), please refer to service information available in TechCONNECT for additional information for TPM diagnosis. Please be aware that if the Wireless Control Module (WCM) is replaced, the TPM placard values may need to be reprogrammed. The TPM placard values do NOT need to be updated if the WCM has NOT been replaced, the TPM placard values are properly set at the factory.

To troubleshoot the issue,go through the help link mentioned below:---
CARS: Working of
tire pressure monitoring systemhttp://technoanswers.blogspot.in/2012/10/cars-working-of-tire-pressure.html-------------
GMC ENVOY spare tire system stopped working?http://repairhelpcenter.blogspot.com/2012/01/gmc-envoy-spare-tire-system-stopped.html

TIRE PRESSURE LIGHT COMING ON?
http://whoisbyme.blogspot.in/2012/07/tire-pressure-light-coming-on.html

What is Best Tire For the Vehicle?http://technoanswers.blogspot.in/2012/04/what-is-best-tire-for-vehicle.html------------
1998 Toyota
Camry: Tires Make Knock Rattling Noise Over Bumps?http://whatisbyme.blogspot.in/2012/05/1998-toyota-camry-tires-make-knock.html

These will help. Thanks.

My work van is a e-series 2011 cargo / work van, the way to reset the tire pressure on it is too push the hazard lights button a few times, may 5 or 6 times pretty quickly when the van is in park and running, the horn will honk and and then you stop pushing the hazard button and wait for a few minutes and the horn will honk agian and the tire pressure light will go out, i dont know if this resets the tires pressure sensor, but the light on the dash goes out, on my van it comes back on after i restart the van , so I am guessing that the sensor on my van is bad. but its worth a shot on your car.

The yellow exclamation mark appears when your TPMS, AKA tire pressure monitoring system picks up on a low-pressure tire. It means that your tires aren't inflated to the recommended pressure. A simple fix is to inflate to the required PSI, and if the problem does not go away, drive down to the nearest garage, as you may have punctured tire at your hands.

TIRE PRESSURE MONITOR SYSTEM
The Tire Pressure Monitor System (TPMS) uses radio and sensor technology to check tire pressure levels. If your vehicle has this feature, sensors are mounted on each tire and wheel assembly, except the spare tire. The TPMS sensors monitor the air pressure in your vehicle's tires and transmit tire pressure readings to a receiver located in the vehicle.

The TPMS is designed to alert the driver, if a low tire pressure condition exists. This system also allows the driver to check tire pressure levels using the Driver Information Center (DIC).

When a low tire pressure condition is detected, the TPMS displays the "CHECK TIRE PRESSURE" warning message on the DIC, and at the same time illuminates the low tire pressure warning symbol.

You may notice, during cooler weather conditions, that the tire pressure monitor light, located on the instrument panel cluster, and the "CHECK TIRE PRESSURE" message will appear when the vehicle is first started and then turn off as you start to drive the vehicle. This could be an early indicator that the tire pressures are getting low and need to be inflated to the proper pressure.

Each tire, including the spare (if provided), should be checked monthly when cold and inflated to the inflation pressure recommended by the vehicle manufacturer on the vehicle placard or tire inflation pressure label. (If your vehicle has tires of a different size than the size indicated on the vehicle placard or tire inflation pressure label, you should determine the proper inflation pressure for those tires.)

As an added safety feature, your vehicle has been equipped with a tire pressure monitoring system (TPMS) that illuminates a low tire pressure telltale when one or more of your tires is significantly under-inflated.

Accordingly, when the low tire pressure telltale illuminates, you should stop and check your tires as soon as possible, and inflate them to the proper pressure. Driving on a significantly under-inflated tire causes the tire to overheat and can lead to tire failure. Under-inflation also reduces fuel efficiency and tire tread life, and may affect the vehicle's handling and stopping ability.

Please note that the TPMS is not a substitute for proper tire maintenance, and it is the driver's responsibility to maintain correct tire pressure, even if under-inflation has not reached the level to trigger illumination of the TPMS low tire pressure telltale.

The "CHECK TIRE PRESSURE" warning message and low tire pressure light (telltale) will appear at each ignition cycle until the tires are inflated to the correct inflation pressure.

The Tire and Loading Information label (tire information placard) shows the size of your vehicle's original tires and the correct inflation pressure for your vehicle's tires when they are cold.

Your vehicle's TPMS can alert you about a low tire pressure condition but it does not replace normal tire maintenance.

NOTICE: Do not use a tire sealant if your vehicle has Tire Pressure Monitors. The liquid sealant can damage the tire pressure monitor sensors.

RESETTING THE TPMS IDENTIFICATION CODES
Each TPMS sensor has a unique identification code. Any time you rotate your vehicle's tires or replace one or more of the TPMS sensors, the identification codes will need to be matched to the new tire/wheel position. Each tire/wheel position is matched to a sensor, by increasing or decreasing the tire's air pressure. The sensors are matched to the tire/wheel positions in the following order: LF TIRE (left front tire on the driver's side of the vehicle), RF TIRE (right front tire on the passengers side of the vehicle), RR TIRE (right rear tire on the passengers side of the vehicle), and LR TIRE (left rear tire on the driver's side of the vehicle).

You will have one minute to match the first tire/wheel position, and five minutes overall to match all four tire/wheel positions. If it takes longer than one minute, to match the first tire and wheel, or more than five minutes to match all four tire and wheel positions the matching process stops and you will need to start over.

The TPMS sensor matching process is outlined below:

1. Set the parking brake.
2. Turn the ignition switch to "RUN" with the engine off.
3. Turn the headlamp switch from "OFF" to the parking lamps setting four times within three seconds. A double horn chirp will sound and the TPMS low tire warning light will begin to flash. The double horn chirp and flashing TPMS warning light indicate that the TPMS matching process has started. The TPMS warning light should continue flashing throughout the matching procedure. The "SERVICE TIRE MONITOR" message will be displayed on the Driver Information Center (DIC).
4. Start with the driver's side front tire.
5. Remove the valve cap from the valve cap stem. Activate the TPMS sensor by increasing or decreasing the tire's air pressure for 10 seconds, then stop and listen for a single horn chirp. The single horn chirp should sound within 15 seconds, confirming that the sensor identification code has been matched to this tire and wheel position. If you do not hear the confirming single horn chirp, you will need to start over with Step 1. To let air-pressure out of a tire you can use the pointed end of the valve cap, a pencil-style air pressure gage or a key.
6. Proceed to the passenger's side front tire, and repeat the procedure in Step 5.
7. Proceed to the passenger's side rear tire, and repeat the procedure in Step 5.
8. Proceed to the driver's side rear tire, and repeat the procedure in Step 5.
9. After hearing the confirming horn chirp for the left rear tire, check to see if the TPMS warning light is still flashing. If it is, turn the ignition switch to LOCK to exit the sensor matching process. If the TPMS warning light is not flashing, the five minute time limit has passed and you will need to start the process over beginning with Step 1.
10. Set all four tires to the recommended air pressure level as indicated on the Tire and Loading Information label.
11. Put the valve caps back on the valve stems. The spare tire does not have a TPMS sensor. If you replace one of the road tires with the spare, the "CHECK TIRE PRESSURE" message will be displayed on the DIC screen. This message should go off once you re-install the road tire containing the TPMS sensor. The "SERVICE TIRE MONITOR" message is displayed when the TPMS is malfunctioning. One or more missing or inoperable TPMS sensors will cause the service tire monitor message to be displayed.

That symbol (tire tread) could mean a low tire pressure. The majority of vehicles today have the low tire pressure warning system, which indicates that one or more of the tires are below the minimum tire pressure. Have the tire pressure checked in each tire. As for turning the warning light off, some vehicles the light will go out after tires are inflated properly. Have them check the owner's manual for resetting warning light. Please inform me as to whether or not it was the tires...thanks.

Make sure that they are inflated to the proper specs for the vehicle. If one tire or more are low then the light will come on. If they are inflated to proper levels, and the pressure light still comes on then you have a sensor issue.

Try this procedure:

On the lower left side of the dash and just to the right of the hood release lever is the reset button.

1. Set all of the tire pressures to the correct pressure including the spare tire because it is also being monitored. The tire pressure light will come on if any one of the tires get below 29 psi, including the spare tire.

2. Turn the ignition to the "On", but don't start the truck.

3. If the light is flashing, then press and hold the button until the light goes out and then release the button.

4. Once the light is out, or if it was out already, press and hold the button until the light blinks 3 times, then release the button.

5. Drive the vehicle over 20 miles per hour for around ten to twenty miles for the vehicle tire pressure management system to relearn and complete the reset procedure.

Try this procedure:

On the lower left side of the dash and just to the right of the hood release lever is the reset button.

1. Set all of the tire pressures to the correct pressure including the spare tire because it is also being monitored. The tire pressure light will come on if any one of the tires get below 29 psi, including the spare tire.

2. Turn the ignition to the "On", but don't start the truck.

3. If the light is flashing, then press and hold the button until the light goes out and then release the button.

4. Once the light is out, or if it was out already, press and hold the button until the light blinks 3 times, then release the button.

5. Drive the vehicle over 20 miles per hour for around ten to twenty miles for the vehicle tire pressure management system to relearn and complete the reset procedure.