Dodge 2008 Ram Pickup 1500 - Manual (Page 26)

If your Remote Keyless Entry Transmitter (RKE) fails to
operate from a normal distance, check for these two
conditions:
1. Weak batteries in transmitter. The expected life of the
batteries is from one to two years.
2. Closeness to a radio transmitter such as a radio station
tower, airport transmitter, and some mobile or CB radios.
Transmitter Battery Service
NOTE: Perchlorate Material – special handling may apply,
see www.dtsc.ca.gov/hazardouswaste/perchlorate
The recommended replacement battery is CR2032.
RKE Transmitter Battery Replacement
24 THINGS TO KNOW BEFORE STARTING YOUR VEHICLE