I have a 7700 series F150 with 95K miles on her. For the last couple months I've noticed an odd whirling/gurgling noise from under the hood...and the noise was consistent with engine RPM. Within the last week or so I've noticed that when I brake hard and the truck comes to a stop (at low RPMs - less than 1500) the brake pedal starts to vibrate slightly as if the ABS was kicking in. I initially thought the master cylinder was going on me...than this winter storm hit us hard and I was unable to switch into 4WD. I'm thinking I have a vacuum issue more than a master cylinder issue...any recommendations on how to check to see if I have a vacuum leak that is creating chaos in systems that are dependent on vacuum to run properly, such as the IWE solenoid and brake system??

 

it may need some ole fashioned maintenance...sometimes the actuators get sticky.... or build up on the front shaft. if it has a vacuum leak it should run poorly. its gonna have to get under it and check some things out


you may have a warped rotor

 

ok thanks...Not sure how the circuit works but I should have noted that the light isn't illuminating on the dash...normally I hear two clicks then the light comes on. I only get one click now and the LED doesn't come on

 

You don't have IWE, you have a front diff lock.