Hi
I am new to the forum under broken circumstances.
error codes:
U1900
U2023

Could someone in simple English explain to me what these mean
It wont engage into 4wd with the selector switch on the dash and every once in awhile the 4wd high and 4wd low flash 3 times and then stop. The mil lights only come on too flash 3xs if I move the dial to switch from 2wd to 4wd sometimes.

I have mechanical ability however code reading is a language in its self. So if you do know please explain it to me like I am a 6year old

Thanks
Robb
Happy Father Day To All You DAD'S!!!

 

Does 4WD actually engage even though the lights are flashing, or does it stay in 2WD? Have you tried going into 4WD Low?

 

No
It stays in 2wd no matter what as I said usually when I move the 4WD selector switch the 4low and 4 high blink simultaneous 3 times that's all that happens. It turned into a 2nd vehicle before sitting for about 1 month the 4wd worked fine and never has ever have me any issues

Thanks for answering!!!

 

ANYONE????????

 

Then I'd say you're looking at replacing either the 4WD shift motor or the 4WD relays in auxiliary relay box 1 just behind the driver's headlight under the hood.

 

The "U" codes are errors on the communication network.

Your truck has at least a half dozen computer modules.
They are connected to one another so they can share data.
They are connceted via a communications network.
The network supports three communication protocols.
Some modules run in the SCP (Standard Corporate Protocol) network.
Some run in the ISO (International Standards Organization) network.
Other modules run in the UBP (Uart Based Protocol) network.
The 4WD module is on the UBP network.

For example, when you shift into 4WD Lo, the 4WD module needs to know the vehicle speed, the BPP (Brake Pedal Position) status, and the MLPS status before it will execute the transfer case shift.

(Instead of each module having to have its owns vehicle speed senor and its own BPP, since these sensors values are calculated by the PCM, the PCM sends these values out over the SCP network. The SCP allows inter-module communication. The 4WD module lives on the UBP network and grabs these values from the SCP network.)

Your "U" codes indicate a problem with the communication network.
U1900 is a fault on the CAN BUS network from the 4WD module.
U2023 is the 4WD module reporting an error on an external network node.

Any work recently done on the vehicle? Anything not plugged in?
Any fuses blown? Any vehicle damage?

 

You sure have a funny way of explaining things in "simple English."

 

Not to sound like a "do Little" but where are the fuses located that need to be checked are in the in the truck or under the hood?

 

No recent done to the truck
What could come unplugged just sitting the driveway in nice SC weather?
No damage like I said last month when I drove it it worked fine.
Where do I check the fuses in the cab or under the hood?
What does the 4high and low randomly blinking 3x's at the same time mean?
93K Miles now, no accidents and I am the 2nd owner bought it with 53K

like I said it really just been sitting my dad had a stroke and I take care of my parents and they leased an Edge so the Expedition has had very little use in the last 2 years. I always try to drive it at least once a month there is also a hesitation and check engine mil light on also but I wanted to deal with the 4X4 1st because the hesitation was there before. The 4wd was used very little when ever I would drive it I would always find a nice loose cinder road and use all of the 4X4 settings just because living in SC there really in very little use for 4x4 unless your off roading, which this thing has never seen mud.

Thank you again for everyone's input!!

 

Can the relays be checked without replacement?
Where are they located?
How expensive are the parts everyone is talking about?
4wd relays and 4wd shift motor?

 

pdqford
Thanks for all of the input but your starting to get alittle to tech for me to 100% understand, I said I would never say this but how would you explain it to your wife? No WISE CRACKS

 

Well then to be honest, you might be in over your head in trying to tackle this issue with just yourself and this forum.

 

Can someone tell me where the main fuse block is? Is there one in the cab?

 

Around here we have chipmunks and red squirrels that just love to get up under vehicles and dine on the wiring.

 

Check both places.