HOW TO: Diagnose your 4x4 system. ESOF
03-15-2019, 12:59 PM
#471
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I'm having all kinds of $wd trouble with my 2011 Expedition. So, I was driving on a rainy day in the back country when I made a wrong turn. I made a u-turn and backed the rear wheels slightly off the road. The rears started to sink a little when I went to pull out and they just sat there and spun (in 4A). So now I try 4H, surely with the fronts on a bit of wet pavement it'll pull out, right? Nope. 4H and 4L were just 2wd with the extra weight to carry around.
So I start doing the rounds of testing. Jack the front up and test that both IWEs are working when motor is off, motor is on, in 2H, 4A, 4H, 4L. They're engaged when they're supposed to be and not when they aren't.
Next I check to see if the transfer case motor is working. I hear it click when switching from 4A to 4H and again going into 4L. In 4L I have the low gearing so I know that the t-case is being switched. Next I put the whole thing on jack stands and run the truck in gear. In 4A it never really engages the front wheels. Every once in a while it will slightly turn them. I'm thinking maybe it's an electronic module issue with deciding when to engage the t-case. So I try 4H and it's the same damn thing. Backs are spinning and the fronts barely move at all. I thought that this is a mechanical lock, but maybe not? I'm not sure how Ford's transfer case works (all I I know is that it doesn't work).
I'm stumped at this point and not really looking forward to taking it to the dealer (had this t-case rebuilt and electronic module replaced 2x already). Replaced the passenger IWE. Now this.
So I start doing the rounds of testing. Jack the front up and test that both IWEs are working when motor is off, motor is on, in 2H, 4A, 4H, 4L. They're engaged when they're supposed to be and not when they aren't.
Next I check to see if the transfer case motor is working. I hear it click when switching from 4A to 4H and again going into 4L. In 4L I have the low gearing so I know that the t-case is being switched. Next I put the whole thing on jack stands and run the truck in gear. In 4A it never really engages the front wheels. Every once in a while it will slightly turn them. I'm thinking maybe it's an electronic module issue with deciding when to engage the t-case. So I try 4H and it's the same damn thing. Backs are spinning and the fronts barely move at all. I thought that this is a mechanical lock, but maybe not? I'm not sure how Ford's transfer case works (all I I know is that it doesn't work).
I'm stumped at this point and not really looking forward to taking it to the dealer (had this t-case rebuilt and electronic module replaced 2x already). Replaced the passenger IWE. Now this.
Ended up back at the dealer who rebuilt the transfer case. They diagnosed at as "something is broken inside the case" and quoted me $3000 to replace the whole tcase. Paid them their diagnonsis fee, picked up a used transfer case with 80k miles on it for $250, had an independent shop install it for $400. That shop actually tore down the transfer case to diagnose the problem. They applied 12v to the electromagnetic actuator and it was dead (pretty sure the dealer "replaced" that). So I was out just inder $800 and now my 4WD works flawlessly.
05-20-2019, 04:30 PM
#473
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IWE problems
I was driving the other day and suddenly heard a noise that sounded like i had run over a nail. It was a "hissing" sound that only lasted for 20-30 seconds. Then I started to hear the grinding that everyone else talks about. When in 4H, the noise stops. I'm hoping that is a check valve or solenoid. This is the first my '09 F150 has done this. Any ideas???
05-20-2019, 05:13 PM
#474
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Maybe trace ALL your hoses from the engine all the way to the IWEs. Pay attention to anywhere the hoses could be stressed, and plastic fittings. Could be the checkvalve, but the pop you heard, and hissing, tells me something came apart. I'll say, you've got better hearing than me to hear vacuum escaping from the cab moving down the road.
If you don't find anything, take a cheap little vacuum pump like Harbor Freight sells, and test everything.
https://f01.justanswer.com/apjp02/a5...568d507f_1.pdf
If you don't find anything, take a cheap little vacuum pump like Harbor Freight sells, and test everything.
https://f01.justanswer.com/apjp02/a5...568d507f_1.pdf
Last edited by johnday in BFE; 05-20-2019 at 05:16 PM.
05-20-2019, 07:21 PM
#475
I was driving the other day and suddenly heard a noise that sounded like i had run over a nail. It was a "hissing" sound that only lasted for 20-30 seconds. Then I started to hear the grinding that everyone else talks about. When in 4H, the noise stops. I'm hoping that is a check valve or solenoid. This is the first my '09 F150 has done this. Any ideas???
Maybe trace ALL your hoses from the engine all the way to the IWEs. Pay attention to anywhere the hoses could be stressed, and plastic fittings. Could be the checkvalve, but the pop you heard, and hissing, tells me something came apart. I'll say, you've got better hearing than me to hear vacuum escaping from the cab moving down the road.
If you don't find anything, take a cheap little vacuum pump like Harbor Freight sells, and test everything.
https://f01.justanswer.com/apjp02/a5...568d507f_1.pdf
If you don't find anything, take a cheap little vacuum pump like Harbor Freight sells, and test everything.
https://f01.justanswer.com/apjp02/a5...568d507f_1.pdf
Only thing I'd add is that I'd start at the wheel side. The flexible rubber hose would be my first guess that one of those popped off. Speaking of those, thoroughly check the connector that they connect to up on the frame. After that, it's a crushed/cracked line(s) somewhere.
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johnday in BFE (05-20-2019)
05-22-2019, 04:15 AM
#476
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I was driving the other day and suddenly heard a noise that sounded like i had run over a nail. It was a "hissing" sound that only lasted for 20-30 seconds. Then I started to hear the grinding that everyone else talks about. When in 4H, the noise stops. I'm hoping that is a check valve or solenoid. This is the first my '09 F150 has done this. Any ideas???
should be able to pull 20lbs vacuum and have it hold everywhere in the system. If it bleeds off you have a leak. Iwes typically take 7lbs to actuate.
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johnday in BFE (05-22-2019)
04-01-2020, 01:50 AM
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Great thread! Wish I would've had it last year. However, I recently had my vacuum lines replaced. Not sure if new solenoid or not. 4WD light does not come on. but 4WD Hi works fine otherwise. Is there something simple that I could do (with limited back-yard mechanical capability), instead of bringing the vehicle in again.
How much did it cost to replace the lines? I can probably do it myself but would rather not. I know that that is my problem. Broke the passenger side installing a lift and driver side grinds now...
07-29-2020, 01:00 PM
#478
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Great thread! I’m hoping to get some advice based on what I’ve read here. I am using a 2018 f150 drivetrain in an early bronco. It has the 10r80 transmission and transfer case. I have a stand alone harness for the transmission and engine. It has manual locking hubs so no vacuum needed. Can I simply operate the the transfer case by just just wiring the motor to engage 4hi and 4lo? This would bypass most of the electronics associated with the vacuum locking hub assemblies and make the project a lot easier to complete. Thanks
07-29-2020, 04:41 PM
#479
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Great thread! I’m hoping to get some advice based on what I’ve read here. I am using a 2018 f150 drivetrain in an early bronco. It has the 10r80 transmission and transfer case. I have a stand alone harness for the transmission and engine. It has manual locking hubs so no vacuum needed. Can I simply operate the the transfer case by just just wiring the motor to engage 4hi and 4lo? This would bypass most of the electronics associated with the vacuum locking hub assemblies and make the project a lot easier to complete. Thanks
