4x4 engaging question.

[thrashin]

im new to the site but this is my second tahoe. i have the famous blinking four wheel drive issue. last truck was only a bad fuse. this one no such luck. fuse good. when in 2hi i can spin front shaft by hand. in four hi the shaft locks but no power to front wheels. what should i check next? thx in advance. 96 tahoe 2dr.

 

[SunlitComet]

in 4wd modes the front drive shaft should turn equally to the rear drive shaft. assuming all four wheels are off the ground or you can very carefully see them moving while on the ground. there is no differential between the two drive shafts them selves. does this help?

 

[WalterMitty]

Front actuator?

 

[thrashin]

i have yet to lift it off the ground to check. when i push the 4hi switch i hear the click on the tcasr. i can move the shaft freely until i hit the switch then the front shaft can no longer turn freely. with the shaft locked i still have no power to the front wheels and the switch only blinks. fuse is good. haynes manual is no help on tcase.

 

[SunlitComet]

it sound like then the front shaft is locking to the rest of the drive-train then. unscrew the front actuator, and maybe catch some lube too. with the ignition on and parking brake on put it in 4hi. ensure the front shaft locks and looks at actuator has it extended or is it still retracted and check the voltage for it in both positions.

 

[thrashin]

it sound like then the front shaft is locking to the rest of the drive-train then. unscrew the front actuator, and maybe catch some lube too. with the ignition on and parking brake on put it in 4hi. ensure the front shaft locks and looks at actuator has it extended or is it still retracted and check the voltage for it in both positions.

what should the voltage be since it isnt in the manual and where exactly is it located?

 

[SunlitComet]

i should also add that if it does extend then shut down screw it back in and plug it back in. try the sequence again. if the light still blinks then disconnect other connector for feed back switch and short together. if light stays steady you may have a broken feedback switch or something wrong internally in the front axle.

---------- Post added at 06:01 PM ---------- Previous post was at 05:54 PM ----------

systems volts. what ever your batt is putting out when truck is not running. front axle. left side iirc. looks like this.

---------- Post added at 06:02 PM ---------- Previous post was at 06:01 PM ----------

there are only four wires going to the axle. 2 for actuator and two four feedback switch.

 

[WalterMitty]

Page 8A-38-2 of electrical diagnosis service manual indicates system volts on light blue wire (see expert comment above) and ground on black wire.

Location "RH Rear side of Front Drive Axle" pg 201-23 fig 35.

 

[thrashin]

ok appreciate all the info. ill let you know what i figure out.

 

[SunlitComet]

yeah i went back to look at the drawing and it shows it on the right side but in front. at any rate here is a reference to it to make it easier.

 

[SunlitComet]

ignore the remove/install section on the left.

 

[thrashin]

I do have 12 volts +/- going to the actuator on the front diff. Thats a plus I guess. I need to work on pulling it out and seeing if it moves in and out as stated before. How much should it move?

-- On a side note i have tools and knowledge but also am still recovering from neck surgery (disc fusion) so I move slow sometimes.

---------- Post added at 02:11 PM ---------- Previous post was at 01:58 PM ----------

Front actuator?

it sound like then the front shaft is locking to the rest of the drive-train then. unscrew the front actuator, and maybe catch some lube too. with the ignition on and parking brake on put it in 4hi. ensure the front shaft locks and looks at actuator has it extended or is it still retracted and check the voltage for it in both positions.

When you say check the voltage- is it that the polarity should reverse as in a motor going one direction or the other?

---------- Post added at 02:44 PM ---------- Previous post was at 02:11 PM ----------

Pulled the acuator and had the kid hit the buttons from 2hi to 4 hi. I hear it clicking in the tcase only. I had the one from the diff hanging in the air while hitting the switches and it doesnt budge. I do have power going to it on the connection (checked with meter). Guess I know what I am buying.

 

[SunlitComet]

if you mean the actuator did not extend and you had voltage to it then yes replace it.

 

[thrashin]

if you mean the actuator did not extend and you had voltage to it then yes replace it.

72 dollars later it seems to be fixed thank you very much for the information and pointing me in thr right direction.