You should check your Tire Pressures regularly, especially prior to a long trip, or after prolonged inactivity or storage. The Tire Inflation Pressure Guide is on a label on the Driver’s Door jamb.
The RAM Promaster is equipped with a “Tire Pressure Monitoring System” (TPMS).
This serves to alert the Driver when an individual tire may be losing air rapidly, and allow for safe stopping. It can also generate an alert when one or more tires are out of the tire inflation range (% or PSI variation) programmed into the TPMS Main Module.
Seasonal changes in ambient temperature can cause the TPMS to trigger an alert. It is not uncommon for a 1-2 PSI change for an increase or decrease in ambient temperature. The alert should be for an individual tire location.
A fault triggered upon start-up can be due to a number of reasons. For example, Driver’s Side parked in direct sun / Passenger Side in shade and cool wind could trigger an alert due to the temperature differential.
A “System Fault” is triggered when there is a malfunction at the TPMS Main Module. The alert “Service Tire Pressure System” is triggered when there is a general malfunction in the TPMS system, and may reset itself after subsequent restarts.
This is outlined in the “What To Do in Emergencies” section of the User Guide that comes with your Promaster. If your TPMS is generating frequent alerts, and your Tire Pressures are within the specified range, visit your RAM Dealer for a system diagnosis.