"AWD OFF" Light

[askoncemore]

What is the cause of this light to come on?

I was on the freeway 2 times today and it randomly came on.
It is a pop up with an "OK" to acknowledge the message.

There are no other lights that stay on after you push ok on the left of the steering wheel

 

[pmezo33]

From your owner's manual:

AWD Off Displayed when the AWD system has been
automatically disabled to protect itself. This is
caused by operating the vehicle with the
compact spare tire installed or if the system is
overheating. The AWD system will resume
normal function and clear this message after
driving a short distance with the road tire
re-installed or after the system is allowed to
cool

 

[askoncemore]

I just changed my rims and tires.... i am curious if this can set it off due to the small change in height.

 

[pmezo33]

I just changed my rims and tires.... i am curious if this can set it off due to the small change in height.

Sounds like this is probably related. 

http://www.explorerforum.com/forums/showthread.php?t=399611

That's someone with a similar issue caused by incorrect tire size.  All four of your tires are the same size, right?  What size wheels and tires?

 

[askoncemore]

Staggered...
275 40 20 front
295 40 20 back

 

[askoncemore]

20" x 9.5" rims

 

[pmezo33]

You might want to consider switching to all four tires being the same size.  Seems like that's causing your awd system to overheat.

 

[Blackhawk]

Your tire heights are different in the front and back by about a half an inch, not sure this is within the tolerances that the car will support.  It expects all wheel to be turning at the same rate.  It's the same reason it disables with a spare tire.

Staggered...
275 40 20 front
295 40 20 back

 

[FoMoCoSHO]

The front and rear need to be within 3% or less of each other, if my calculations are correct you are about 7% off.

 

[J-Will]

He's not the first to run staggered. While it seems too coincidental to not investigate, I have a hard time definitively stating that this is the cause.

Edit- FoMoCo just provided actual data rendering my response invalid

Sent from my Nexus 6P using Tapatalk

 

[Blackhawk]

The 275/40 is the same height as the stock tires, 28.7 inches.  The 295/40 is 29.3 inches tall.  If you wanted to go with a wider tire in back you could have done a 315/35 but that would be 12.4 inches wide which your 9.5 inch wide rim would not support.

 

[FoMoCoSHO]

For comparison BPD's staggered setup is 3.51 % from front to rear.

 

[TooFast4SHO]

I got this for a calculation

Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile  Difference
275/40-20        4.3in  14.3in    28.7in        90.0in        704        0.0%
295/40-20        4.6in  14.6in    29.3in        92.0in        689        2.2%

 

[FoMoCoSHO]

If you break it down by mm, I come up with 110 for the front and 118 for the rear.

110 is 93.22% of 118

What I can't remember is if the 3% number is diameter or sidewall height.

I do know that seriously uneven treadwear has cooked some local LEO PTUs, so I'd say there's not a ton of wiggle room. Apparently this is pretty common...

"The PTU is not a viscous coupling.  Its basically a ring and pinion bolted to the transaxle.  The viscous coupling is attached to the rear axle.

To go along with fordtech1's uneven tire wear comment I have seen uneven tire wear (front to rear) prematurely break down the lubricant on utility interceptors in as low as 30,000 miles.

I just wish they had a higher lube capacity.  Its only .56 quarts!  I'm no engineer, but I feel a higher capacity may help.  It won't help if the rear tires are bald and the fronts are new though."

http://www.blueovalforums.com/forums/index.php?/topic/59381-ptu-issues-possible-long-term-solutions/

You didn't by chance exceed 100 MPH when it happened did you? Both SHO's liked to shutdown AWD when I cross 100 at the track.

The easiest solution if it continues is put the stockers back on and see if it stops, I'm afraid that id the only definite answer you will get.

If you take it in I'd suggest having them call the hotline regardless of what the advisor says, maybe you can get an official answer from them.

 

[66 Galaxie]

My math agrees with FoMoCoSHO's math and as stated you are too far off so the awd is shutting down before it grenades on you.

 

[askoncemore]

AWD Off did not turn on again on a return trip of 60 miles.

Spirited driving from 0-80 MPH.

 

[Brucelinc]

With that much difference in tire sizes, you are playing with fire.  Maybe you will not get burned....today...or tomorrow.....but you likely will at some point.

 

[ajpturbo]

Bruce how did you measure your 0-60 in your sig?

Side note: when i drag race pretty much everytime at the end i get "service advance trac " indicator. I restart the car and its fine...ive gone 150mph in the car before and its fine....i think its from brake boosting at the launch that it doesnt like....at the strip is the only time i brake boost

 

[ZSHO]

Bruce how did you measure your 0-60 in your sig?

Side note: when i drag race pretty much everytime at the end i get "service advance trac " indicator. I restart the car and its fine...ive gone 150mph in the car before and its fine....i think its from brake boosting at the launch that it doesnt like....at the strip is the only time i brake boost

AJ Doing 150mph how long is the Track.?  BTW Please be safe.  Z

 

[ajpturbo]

Bruce how did you measure your 0-60 in your sig?

Side note: when i drag race pretty much everytime at the end i get "service advance trac " indicator. I restart the car and its fine...ive gone 150mph in the car before and its fine....i think its from brake boosting at the launch that it doesnt like....at the strip is the only time i brake boost

AJ Doing 150mph how long is the Track.?  BTW Please be safe.  Z

No track