'05 ESOF Vacuum Pulse Hublock testing

[RandyH]

Hi All,

Been working on figuring out why my hubs are not locking in with the vacuum system. Tested the vac tube feeding the front hubs from where it leaves the PVH and it holds a vacuum fine and doesn't leak off so no vacuum line or hub seal issues. Also verified with a vac gauge that the pump is working and shuts off when it reaches a little over 15". Manual hub lock with the switch to 4 x 4 high and low works fine.

So that leaves me with the PVH solenoid not turning on and vacuum pulsing the hubs. The solenoid was replaced once already at about 80k (6 years ago when I bought the truck) and all indications are that it has failed again. However, before I spend the $60 or so I was wanting to see if I can confirm the PVH is getting the signal to turn on the vacuum to the hubs.

I have battery voltage on the center wire whenever the ignition is on and doesn't change if switch is moved from two wheel to four wheel. Does anyone know what the other two outer wires should show when the switch is changed between 2x and 4x? Thanks. Randy

Also checked fuses 31 and 33 in the cab and #3 (ESOF) under the hood that are 4x4 related. Fuses are okay but I never had power to 31 with key on and the ESOF switching between 2 wheel and 4 wheel.

 

[f100cleveland]

Good luck finding your problem. I think they told me it was a jem module that was bad and it would be hundreds to fix it. I lock my hubs in when I need them because like yours it works fine except for the shift on fly part.

 

[RandyH]

That's what I'm afraid of.

Anybody know how to test the output of the GEM (inputs to the PVH)?

 

[RandyH]

Found a lot of good troubleshooting info in this link. Going to poke around some more and if no joy will probably end up going ahead and replacing the PVH as everything seems to be pointing to it. Following the logic it appears that a DTC code would be likely for a control module (GEM) issue.

http://www.twistedandes.com/foro/attachment.php?attachmentid=79640&d=1265635512

Edit: And this one for Ranger seems to be the same basic ESOF system and includes voltage and coil resistance values which is a huge help. All the GEM inputs appear to be correct, the solenoid is just not allowing vacuum through. Going to order the PVH next.

http://rockledge.home.comcast.net/~rockledge/RangerPictureGallery/PVHDiagnostics.pdf

 

[RandyH]

Update - my replacement PVH arrived today (Dorman 600-402), install took about 10 minutes with half of that used to find the correct socket. Plugged everything in and hooked up the vacuum gage to the PVH output and switched from 4 x 2 to 4 x 4 and it worked! Took the gage off and connected the valve to the hub lines and could then hear the hubs switching in and out when actuating with the ESOF switch in the cab. One thing to remember is that the valve only turns on for about a minute each time the ESOF is switched on or off as it just pulses it. The hubs do not use or need a constant vacuum source. Saw it compared to a pen being clicked once to extend and again to retract. Anyway all done with that issue. Now waiting for my blue spring to arrive for the next project.

Edit - the Dorman PVH part on-line is about 2/3 the cost of OEM and since at least two of the OEM parts have died in the six years I've had the truck, I thought I'd try something different this time.

 

[RSG]

Glad that worked. Good detective work!