A dielectric anomaly induced by doping has been observed at about 340 K in chlorine doped diisopropylammonium bromide (DIPAB-C). The dielectric anomaly has a switchable behavior, which indicates potential applications on switches and sensors. Temperature dependent Raman spectrum, X-ray diffraction and DSC do not show any anomaly around the dielectric anomaly temperature, which prove that the dielectric anomaly does not come from structure phase transition and has no specific heat variety. It is assumed that this relaxation process can be attributed to the freezing of ferroelectric domain walls induced by the pinning of point defects.