4WD Problems

[K1LDZR2]

Does anybody have trouble-shooting suggestions for this with my 2010 5.4 L?

Flipping the knob into 4L or 4H results in a "CHECK 4x4" message displaying in the IC, but no other indicator lights illuminated. Torque doesn't show any DTCs. There's no grinding sounds. The transfer-case motor is new.

In the process of replacing the vacuum solenoid, I broke the vacuum hose and need to replace it. But I discovered something strange: the two-pin harness to the solenoid is always powered, regardless of whether the 4WD selector know is in 2H, 4L, or 4H. If I understand correctly, the solenoid should be shorted to ground in 4L/4H such that the IWE couplers are no longer held back and are allowed to engage.

Any ideas what to look at from here?

 

[K1LDZR2]

Part of me wonders if it's the power constantly being supplied to the solenoid... The way the controllers seem to work, they use transistors to bridge the gap between controller I/O and the powered connections. It's not shown in this wiring diagram, but maybe there's a FET inside the TCCM that's failed?

 

[K1LDZR2]

Like, the FET could fail open, which wouldn't allow current to flow through the solenoid...

 

[K1LDZR2]

Or since there's a voltage between the harness pins, I guess it means that it failed open?

 

[K1LDZR2]

The Mode Selector Switch is hardwired to the TCCM, so it's not like there's multiple modules involved in this problem, I don't think. And since there's the message that gets displayed on the screen when selecting 4L or 4H, I'm thinking that the switch itself is fine. Maybe it's just a matter of a broken FET somewhere, and the quickest solution would be to replace the TCCM...?

 

[pat247]

Does anybody have trouble-shooting suggestions for this with my 2010 5.4 L?

Flipping the knob into 4L or 4H results in a "CHECK 4x4" message displaying in the IC, but no other indicator lights illuminated. Torque doesn't show any DTCs. There's no grinding sounds. The transfer-case motor is new.

In the process of replacing the vacuum solenoid, I broke the vacuum hose and need to replace it. But I discovered something strange: the two-pin harness to the solenoid is always powered, regardless of whether the 4WD selector know is in 2H, 4L, or 4H. If I understand correctly, the solenoid should be shorted to ground in 4L/4H such that the IWE couplers are no longer held back and are allowed to engage.

Any ideas what to look at from here?

View attachment 443776

This is from the 2014 ford wiring diagrams

 

[pat247]

I'll add these also.

 

[FordTechOne]

With a “Check 4x4” message, should have DTCs in the TCCM. Most “generic” OBD2 scanners cannot pull those codes. You’ll need something like ForScan to access the TCCM.

As far as the IWE system, Fuse F29 supplies power to the solenoid at all times. To supply vacuum to the IWEs and disengage them, the TCCM grounds circuit CCF05 BN-BU. That energizes the solenoid and allows vacuum to the IWE lines. You’ll still have voltage on SNB29, as it drops across the solenoid, it is not “shorted” to ground.

 

[K1LDZR2]

With a “Check 4x4” message, should have DTCs in the TCCM. Most “generic” OBD2 scanners cannot pull those codes. You’ll need something like ForScan to access the TCCM.

As far as the IWE system, Fuse F29 supplies power to the solenoid at all times. To supply vacuum to the IWEs and disengage them, the TCCM grounds circuit CCF05 BN-BU. That energizes the solenoid and allows vacuum to the IWE lines. You’ll still have voltage on SNB29, as it drops across the solenoid, it is not “shorted” to ground.

Thanks. I've debated trying ForScan, but I believe it only with with Windows, right? I don't currently have that at home. I need to figure that part out, but I might just have to resort to a VM or something on a Linux box.

I think I could have more clearly communicated what I was saying. So yes, there's always a voltage on one of the harness pins, because it's tied to a hot wire. But the other harness pin (#2) is connected to the TCCM, which should toggle that pin between Hi-Z ("open") and closed, the latter of which would complete the circuit. Am I understanding this correctly?

But my problem is that pin #2 is always grounded no matter what. I'll look into this deeper after work - probably gonna see if there's continuity between ground and the pin when the truck is on, off, on with the 2H setting, on with the 4L/H setting, etc.

 

[K1LDZR2]

I can't see much from work, but it does appear that some users have been able to get ForScan working under Wine, which might be my ticket...