2006 Pontiac Montana continuous running of motor

Probably the air pump for the air shocks on the rear of the van. Look under the rear end of the van and you will see some small plastic tubing coming from the rear shocks that is about 1/8 in. Diameter, may be black or white/clear tubing. See if it has came loose or busted and blowing a small amount of air out of a loose end. You may not be able to hear it for the pump noise so also feel around the tubing for leaks or spray with soapy water in a pump spray bottle. Tubing kits should be availible at aftermarket parts stores and can be done by someone with mechanical skills. Beware shock itself may be busted and leaking internally.