Here's the TSB on TPMS.
NUMBER: 22-002-07 REV. A
GROUP: Tires & Wheels
THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 22-002-07, DATED JUNE 29, 2007, WHICH SHOULD BE REMOVED FROM YOUR FILES. ALL REVISIONS ARE HIGHLIGHTED WITH **ASTERISKS** AND INCLUDES AN ADDITIONAL INFORMATION IN REFERENCE TO TIRE ROTATION SERVICE.
Tire Pressure Monitor System (TPMS) "Light Load" Reset Switch ** and Tire Rotation Caution**
This bulletin provides information for New Vehicle Prep; setting tire pressures and the Light Load switch.
**This bulletin also provides information regarding tire rotation routine service. **
2008 (DH) Ram Truck 2500
The Tire Pressure Monitor System (TPMS) "LIGHT LOAD" reset switch will allow the driver to switch between the MAX LOAD INFLATION PRESSURE (COLD) low pressure warning threshold and the LIGHT LOAD INFLATION PRESSURE (COLD) low pressure warning threshold depending on the vehicle's load condition. The tire and loading information label defines the recommended front and rear cold tire inflation pressures for the vehicle when operating in the MAX Load condition. A SUPPLEMENTAL TIRE PRESSURE INFORMATION label is also included defining Light Load tire inflation pressures when operating in the Light Load condition. When the "LIGHT LOAD reset switch LED is ON, the TPMS is using the light load inflation pressure (cold) low inflation warning threshold.
SPECIAL TOOLS/EQUIPMENT REQUIRED:
CAUTION :**When performing tire rotation service to this vehicle, tire pressures MUST be adjusted to the specified inflation pressures as stated on the SUPPLEMENTAL TIRE PRESSURE INFORMATION label located on the rear face of the driver door. After service is completed, the TPMS will need to relearn the location of the sensors. This can be accomplished by driving the vehicle over 15 mph (up to 10 minutes) until the system updates and the TPM light in the instrument cluster goes off. This must be completed before returning the vehicle to the customer. **
TPMS NEW VEHICLE PREP PROCEDURE:
1. Turn the ignition switch to the RUN position, (engine off).
2. Adjust all four tires pressures to the LIGHT LOAD INFLATION PRESSURE values as listed on the SUPPLEMENTAL TIRE PRESSURE INFORMATION label. The SUPPLEMENTAL TIRE PRESSURE INFORMATION label is located on the rear face of the driver door (Fig 1).
NOTE :Use an accurate tire gauge to check the tire pressures.
3. Is the LED on the Light Load Switch illuminated?
a. Yes >> Procedure is complete.
b. No >> Proceed to Step # 4
4. After all four tire pressures have been lowered to the "LIGHT LOAD" INFLATION PRESSURES, press the "LIGHT LOAD" switch located on the vehicle center bezel. If the "LIGHT LOAD" switch's amber colored LED turns ON solid, the TPMS is using the LIGHT LOAD TIRE INFLATION PRESSURE (COLD) threshold.
NOTE :If the "LIGHT LOAD" switch amber colored LED flashes on and off for 10 seconds, after all four tire pressures have been set to the LIGHT LOAD INFLATION PRESSURE specifications, one or more of the four tires may NOT be at the correct LIGHT LOAD TIRE INFLATION PRESSURE (COLD) value as indicated on the SUPPLEMENTAL TIRE PRESSURE INFORMATION label. Recheck all four tires and be sure to set all four tires to the specifications indicated on the SUPPLEMENTAL TIRE PRESSURE INFORMATION label.
CAUTION: The TPMS has been optimized for the original equipment tires and wheels. TPMS pressures have been established for the tire size equipped on your vehicle. Undesirable system operation or sensor damage may result when using replacement equipment that is not of the same size, type, and/or style. After-market wheels can cause sensor damage. Do not use aftermarket tire sealants or balance beads if your vehicle is equipped with a TPMS, as damage to the sensors may result.
CAUTION: After inspecting or adjusting the tire pressure always reinstall the valve stem cap. This will prevent moisture and dirt from entering the valve stem, which could damage the Tire Pressure Monitoring Sensor.
CAUTION: Tire pressure sensor valve stem caps and cores are specially designed for the sensors. Due to risk of corrosion, do not use a standard valve stem cap or core in a tire pressure sensor in place of the original equipment style sensor cap and core.
CAUTION: Any time a sensor is to be reinstalled in a wheel, a new seal, nut, cap and valve core must be installed on the stem to ensure air tight sealing.
NOTE: TPM thresholds have been established for the original tire size equipped on the vehicle. Use original size tires only to maintain system accuracy.
The battery operated tire pressure sensor is both a transmitter and a receiver. The TPM sensor can be forced to transmit if using a special tool such as a TPM-RKE Analyzer, or from a transponder. The TPM-RKE Analyzer has the ability to change the sensor mode and to diagnose a faulty TPM sensor. Using a TPM-RKE Analyzer can take up to a minute to force a transmission from a sensor.
The High Pressure TPM sensor can be in one of the following modes:
Sleep Mode - A new TPM sensor will be in this mode. If placed on the vehicle as a road tire, the TPM sensor will transmit once every 20 seconds when the vehicle is driven at speeds over 15 mph (24 km/h). If the vehicle is not moving, the sensor will only transmit on a pressure change greater then 2 psi (13.8 kPA). Driving the vehicle continuously at speeds over 15 mph (24 km/h) for more then 4 minutes will change the sensor state into 30 BLOCK MODE. The TPM sensor will not return to SLEEP MODE. Now, if the vehicle has been stopped for 20 minutes, the TPM sensor state will change to PARK MODE.
Park Mode - This is the correct mode when the vehicle is not moving. The sensor will transmit once every 13 hours to update the WCM, or will transmit on a 2 psi (13.8 kPA) delta change. The sensors will internally take a measurement of the tire pressure every minute to determine a change in tire pressure.
30 Block Mode - If the vehicle has not been moving for more then 20 minutes, or if the sensor's mode was forced to Park Mode using a TPM-RKE Analyzer, the sensor's operating mode will transition from PARK MODE to 30 BLOCK MODE once the vehicle is driven over 15 mph. In this mode, the sensor will transmit once every 15 seconds when the vehicle is driven at speeds over 15 mph (24 km/h) for the first 30 transmissions. After 8 minutes of continuous driving above 15 mph (24 km/h), the TPM sensor will change to DRIVE MODE.
Drive Mode - In this mode, the sensor will transmit once every minute when the vehicle is driven at speeds over 15 mph (24 km/h). At any time that the vehicle speed drops below 15mph, the sensor will not transmit. The sensor mode will still be in drive mode when the sensor reaches speeds over 15 mph (24 km/h). If the vehicle has been stationary for more then 20 minutes, the TPM sensor will change to PARK MODE.
Each sensor's (transmitter) broadcast is uniquely coded so that the wireless control module (WCM) can monitor the state of each of the sensors on the four rotating road wheels. The WCM can automatically learn and store the sensor's ID while driving "within 10 minutes continuously above 15 m.p.h. (24 Km/h)" after a sensor has been replaced. The vehicle must be stationary for more then 20 minutes in order to initiate the learning sequence.
The sensor IDs can also be programmed using the TPM-RKE Analyzer Tool. Scan each TPM sensor at each road wheel, and store each Sensor ID in the correct location. (LEFT FRONT, LEFT REAR, RIGHT FRONT, and RIGHT REAR) Connect the TPM-RKE Analyzer Tool to the Scan Tool. Then follow the programming steps outlined in the diagnostic Scan Tool for "Program Tire Pressure Sensor ID w/ TPM Tool" under "MISC" for the "WCM/WIRELESS CONTROL MODULE".