04' GMC Sierra quadrasteer, trec fuse 30a blows when trying to engage 4wd. I replace fuse, start truck and 4wd auto is lit up but if I press 2h, 4h, or 4 low it blows. What should I do or look for?

I assume 2WD and 4WD selection work just no indicators are lit?

Check power from TREC fuse, 30A engine compartment fuse block.

Check LED power voltage at the switch assembly PPL/WHT wires. Power is provided by the LED dimming control.

Does interior dimming work?

freezed

My 2005 Sierra 4x4 did the same thing while running down the interstate on vacation. Scared me to death, thought it was going to shift into 4 wheel drive @ 80 MPR. Had to take to shop and they found a censor bad and they replaced it. Don't know cost, because truck was still under warranty.

Possible actuator motor issue have it tested.

1. • 1 Start your Dodge truck's engine.
     
   • 2 Turn the electronic transfer case from "2WD" to "4WD Lock" to engage the high range 4WD, if the dodge truck is equipped with an electronic transfer case; otherwise, shift the transfer case lever from "2H" to "4H." The electronic transfer case is located on the instrument panel and is marked with "2WD," "4WD Lock" and 4WD Low." The lever-equipped transfer case is located to the right of your leg and is marked with "2H," "4H" and "4L."
     
   • 3 Shift the transmission into "Neutral" while the vehicle is either stopped or rolling at 2 to 3 mph to begin engaging in the low range 4WD. Turn the electronic transfer case to "4WD Low," if the Dodge truck is equipped with an electronic transfer case; otherwise, shift the transfer case lever from "2H" or "4H" to "4L."
     
   Tips & Warnings
   • Indicator lights will come on and alert you that your vehicle is in either the high or low range of 4WD.
     
   • Do not engage in the low range of 4WD drive if the transmission is in gear; you must shift to "Neutral" first.
     
   • Many Dodge trucks allow you to shift from 2-wheel drive to the high range of 4WD at up to 55 mph--consult your truck's manual to ensure that this is possible. Do not exceed 55 mph while engaged in the high range of 4WD. Do not exceed 25 mph while engaged in the low range of 4WD.
     
   • Do not engage in 4WD unless you are on slipper or rocky roads.
     

4L only to be used in extreme condtions
N
4H for off road/snow/ice
2H - normal driving

when switching to 4H vehicle must be stationary, as when changing from 4H to 4L
but it is possible to change from 4H back to 2H while in motion.
when 4wd is engaged a lamp will illuminate on dials telling that the hubs are free wheeling, when changing back to 2H you must press corresponding switch to dis-engage this function

Check/change transfer case fluid and check the wire connection to it.

There is a TSB on this problem: TSB #03-04-21-001C

Subject:4WD Switch Indicator Lights Flashing, 4WD Inoperative, DTCs C0327, P0500, P0836, P1875 Set (Replace Encoder Motor Sensor, Reprogram TCCM, Inspect Front Drive Axle Engagement Sleeve for Damage/Repair) #03-04-21-001D - (12/04/2003)



Models:2003 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2003 GMC Sierra, Yukon, Yukon XL
with 4WD and Electric Shift or Active Transfer Case (RPO NP1 or NP8)
You can also try removing the TREC fuse (engine fuse box) and reinstall after 30 seconds. Look up the TSB number I gave you and you'll find alot more information.

Check the super select solenoids. I had the same problem with my pajero/montero io, when I released 4WD from 4H to 2H the two front wheels lights started flashing. They stopped flashing and was solid on when I re-engaged the 4WD (2H to 4H).

My problem was a failure in the 2H solenoid, it was not producing enough vacuum. The problem was intermitent at the begining and then was permanent.

I checked the solenoids in this way:
1) The solenoid that receives the vacuum in the botton is for 2H
2) The solenoid that receives the vacuum in the top is for 4H
3) Both solenoids operate in the same way, they only change in the way they transfering vacuum from top/botton to the exit pipe (2H or 4H). The difference is that one has the vacuum input on the top and the another one in the botton.
4) The default position when you disconnect the electronics is 4WD
5) Try disconnecting the electronics and switching the output pipe between the solenoids. This will put the solenoids on 4WD position and you changed the pipes, so the 4WD should disengage.

4WD should disengage if your 4H solenoid is OK, the ligths should now flash when you change from 2H to 4H because 4WD cannot engage because the pipes are switched. You can also check the vacuum of each solenoid with your finger on each one.

If this doesn't work, try to bypass the solenoids and connect the input vacuum hose to the 2H output pipe. If the lights doesn't turn off in 2H mode it's posible that you have different problem.

Also check this address: http://4wd.blogeasy.com/article.view.run?articleID=318776

Good luck.