dc Posted February 21, 2008 Share Posted February 21, 2008 This is my personal truck. (2007 F350 diesel ESOF) Would not engage 4x4, no 4X4 light, with or without hubs engaged. Was away at meetings and dealer installed new motor. Worked sometime and then not. Hotline said try another motor and 4X4 module. Truck will now engage 4X4 when hubs are engaged or when truck is stopped. Will not engage when moveing with hubs in auto. Dealer insists hubs not at fault because 4X4 dash light is not on. What else could it be. Quote Link to comment Share on other sites More sharing options...
LARRY BRUDZYNSKI Posted February 21, 2008 Share Posted February 21, 2008 Could it be your range switch? I have seen moisture intrusion and corrosion there at the connector, but usually have more problems pop up because of the corrosion. Quote Link to comment Share on other sites More sharing options...
dc Posted February 21, 2008 Author Share Posted February 21, 2008 Could it be your range switch? I have seen moisture intrusion and corrosion there at the connector, but usually have more problems pop up because of the corrosion. I've looked at switch and connector, nothing obvious. It engages every time with hubs on manual or stopped with hubs in auto. Quote Link to comment Share on other sites More sharing options...
LARRY BRUDZYNSKI Posted February 21, 2008 Share Posted February 21, 2008 Well, I see your from Montana, obviously real cold there, and you use the 4wd all the time. What about your ESOF switch, does it change from 2-4 real crisp or a little loosey-goosey, seen those go bad too. Other than that I have seen the thick axle seals go bad and leak pressure causing a no shift situation, but usually is not intermittent. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted February 21, 2008 Share Posted February 21, 2008 The obvious question is "are there any codes?". These are fairly simple systems, but they can work in unexpected ways.... and the dash indicator (or lack of it, is odd...). When the switch is turned to 4HI, the module drives the shift motor while watching the contact plates... Once the plates indicate that the transfer case is in the desired gear, the module sends a timed vacuum pulse to the PVH solenoid as well as a signal to the cluster to turn on the light. The part with the hub vacuum is to ensure that the front driveline is up to speed before the hubs are commanded (not a pretty sound if it soesn't happen that way). Also possible is that the truck may be overdue for a spindle service. The large seals in the steering knuckles can leak enough vacuum to keep the hubs from operating properly... They may leak when rotating but seal fairly well when stationary (or vice versa). They can be tested with a hand vacuum pump. The workshop manual describes this system very well and in great detail... I would suggest that the tech at the dealer peruse this section so that he might understand this system as he needs. Try this... with the heater on either vent or floor, engage 4WD while moving.... does the HVAC system switch to defrost for a short period of time? If so, this would signal a vacuum problem. With the truck stabilized in 2WD, can you turn the front driveshaft by hand? If not, turn the hubs to lock and back to auto (this should unlock them) and try again.... I have seen concerns with the mode synchro in these transfer cases (doesn't usually result in no 2WD... but I haven't seen everything there is to see.......... yet...). Quote Link to comment Share on other sites More sharing options...
LARRY BRUDZYNSKI Posted February 21, 2008 Share Posted February 21, 2008 Quote: Also possible is that the truck may be overdue for a spindle service. The large seals in the steering knuckles can leak enough vacuum to keep the hubs from operating properly... They may leak when rotating but seal fairly well when stationary (or vice versa). They can be tested with a hand vacuum pump. I'm glad I'm not the only one that thought of this...Thanks Jim you explained it a whole lot better than I could /forums/images/%%GRAEMLIN_URL%%/thumbup.gif Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted February 21, 2008 Share Posted February 21, 2008 They can be tested with a hand vacuum pump. Are you nuts? You will pump for an hour trying to pull a decent vacuum. Then again, some guys are used to that. /forums/images/%%GRAEMLIN_URL%%/whistle.gif Get a vacuum tee, some bulk vacuum line, then you can tee in a gauge and use the electric vacuum pump on the truck for a source. You can test both sides from the connector at the pulse vacuum solenoid or go directly to each steering knuckle. Clip on a small Vice-Grip and check for leak-down. Do the same with the hub tester too. From there, the really committed tech can plug in the smoke machine... remember to turn the steering lock to lock when testing for a vacuum leak. Those seals can play games with you! Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted February 21, 2008 Share Posted February 21, 2008 Pump for hours? All I ever use is a hand pump... Test each knuckle individually, cap off the lines and test those as a sub-assembly... And it only takes a few minutes... Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted February 21, 2008 Share Posted February 21, 2008 You know I was exaggerating right? But still, I have no patience to pump down a hub and since I started using the pump and a jumper hose I rather prefer doing it that way. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted February 22, 2008 Share Posted February 22, 2008 Sorry, Kieth... I'm still hovering in that limbo where some humor is lost on the old fart... Some days I think the only reason I go to work is because I want to see what happens next.... But I remember an old Scottish saying... "What doesn't kill me can only make me stronger....". Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted February 22, 2008 Share Posted February 22, 2008 But I remember an old Scottish saying... "What doesn't kill me can only make me stronger....".Who needs stronger wrists? /forums/images/%%GRAEMLIN_URL%%/rofl.gif Quote Link to comment Share on other sites More sharing options...
LARRY BRUDZYNSKI Posted February 26, 2008 Share Posted February 26, 2008 dc, any outcome to the problem??? Quote Link to comment Share on other sites More sharing options...
dc Posted February 26, 2008 Author Share Posted February 26, 2008 I'm on the road for another full week. Truck will engage 4x4 when hubs are locked in. Will not engage in auto unless truck is stopped. Did have time to vacuum test each hub independently. Both hubs held vacuum. The truck did have a code for bad motor on transfer case. This was changed twice. The last change per hotline. I have scheduled a couple of days for repairs next week. Quote Link to comment Share on other sites More sharing options...
LARRY BRUDZYNSKI Posted February 29, 2008 Share Posted February 29, 2008 If the motor has a two-fer going right now, I think I would be looking elsewhere, wiring,switches,relay... something else on the circuit causing the problem. Maybe chaffed wires somewhere. Has anything been worked on this truck recently??? Quote Link to comment Share on other sites More sharing options...
dc Posted March 6, 2008 Author Share Posted March 6, 2008 Synco in tranfer-case broke. Quote Link to comment Share on other sites More sharing options...
LARRY BRUDZYNSKI Posted March 6, 2008 Share Posted March 6, 2008 What makes you come up with this diag? Seen it before? Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted March 6, 2008 Share Posted March 6, 2008 Larry... this is a possibility, though it seems to be working opposite to the few that I have gotten... On mine, the synchros pretty much "fell apart". This allowed the gearmotor to show that the T-case had engaged 4X4... With this indication, the module sends the signal to the PVH solenoid... since the front driveline isn't up to speed, one can imagine the noise when the hubs try to engage.... For dc's case, it sounds like the synchro wouldn't let the gearmotor engage uinless conditions were just right... (FWIW, the module will only attempt to shift the transfer case about 5 times....It tries to make the shift and, if it doesn't see the plate PIDs change, it will pause for a few seconds and then try again). After five attempts, it gives up and sets a code. If we later try to select 4WD again, the same chain of events will occur... Now... the oversight.... if there is a 4 wheel drive concern, the very first thing to do is to check that both hubs engage when commanded and that (whether the 4X4 light is on or not) physically test the front driveshaft to see if the transfer case has made the transistion into the selected mode.... Rule of thumb but NOT cast in stone... If the indicator light comes on, it is "usually" a vacuum concern.... if the light doesn't, it is transfer case or gearmotor related. Quote Link to comment Share on other sites More sharing options...
dc Posted March 7, 2008 Author Share Posted March 7, 2008 Transfer case is torn down. Syncro broken. Quote Link to comment Share on other sites More sharing options...
BrunoWilimek Posted March 7, 2008 Share Posted March 7, 2008 Originally Posted By: Jim Warman They can be tested with a hand vacuum pump. Are you nuts? You will pump for an hour trying to pull a decent vacuum. Then again, some guys are used to that. /forums/images/%%GRAEMLIN_URL%%/whistle.gif Get a vacuum tee, some bulk vacuum line, then you can tee in a gauge and use the electric vacuum pump on the truck for a source. You can test both sides from the connector at the pulse vacuum solenoid or go directly to each steering knuckle. Clip on a small Vice-Grip and check for leak-down. Do the same with the hub tester too. From there, the really committed tech can plug in the smoke machine... remember to turn the steering lock to lock when testing for a vacuum leak. Those seals can play games with you! I realize the problem has already been found, but I wanted to post what I find works even better than a vacuum pump is to hook up the smoke machine(used for evap testing)to the vacuum port on the hub. Watch for the smoke and you have found your leak(s). Quote Link to comment Share on other sites More sharing options...
LARRY BRUDZYNSKI Posted March 8, 2008 Share Posted March 8, 2008 Nice idea /forums/images/%%GRAEMLIN_URL%%/cheers.gif Quote Link to comment Share on other sites More sharing options...
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