xkmgx

before i get started my truck has an aftermarket 4x4 solonoid i have the stock one still just as a spare recently my 2005 f150 has developed a problem as i was leaving my driveway the front end started making a terrible grinding noise and than would fade off about 10 seconds later and be good until i put it in park and turned the ignition off i disconnected the 4x4 solonoid and problem dissapeared i than bought a new aftermarket solonoid and the problem was fixed for about a month and than it happened again while driving so i had the spare factory ford one at home and decided to try that one so i put it in and wham no more noise but now the truck wont go into 4 high but will go into 4 low so i put the aftermarket back in and the noise came back and 4 high and low both work no problem so either i get a grinding noise and both my 4h and 4l work with the aftermarket solonoid or i get no grinding but my 4 high wont work what the hecks goin on!!!! im thinkin bout goin to ford and gettin a brand new solonoid from them instead of the aftermarket ford wants 80$ for one and the aftermarket is 30$

bluefox_gt

I would pull vacuum at each IWE and see if they hold vacuum. Then if that checked out good I would vacuum check the vacuum lines and see if they hold vacuum. Then I would check to see if the IWE solenoid was getting vacuum from the engine. I would about bet you have a IWE bad. Also check your one way vacuum check valves there around the IWE Solenoid and under the PCM.