I have a 1995 Nissan Pickup SE with around 114,000 miles. Within the last 6 months I've noticed a vibration /growling noise coming from the truck when it's NOT running and the ignition is off. I thought at first the noise may be coming from the emergency brake, however I've tested with the brake off and on a level surface and the noise still occurs. The noise only last few a few seconds and seems to happen at random times. I never hear it when the truck is running. Any ideas what this may be coming from? I'm baffled.
Thanks! Dave