4wd switch on the fritz? (**Solved**)

[dualsport]

**Solved**
The electrical connectors in the 4WD dash switch were 'loose.'
I cleaned them with an eraser and then put a slight tweak/bend in all the male pins so that the connectors would have a more positive pressure inside the harness (I could really feel the difference when 'carefully' putting them back together).

So far, so good...

Thanks for all the help and ideas!





Occassionally my 4wd switch is not indicating what state it's in. I use 4wd all the time up here and i'd kinda like to know, ya know?!?!

Anybody know the ins and outs of how these switches operate? I'm pretty sure that mechanically they run on a vacuum system, b/c of my sister-in-law's s10 and a very exciting driveway 'incident' I became a part of but I'm more curious about why the LED's light up- or don't light in this case... I just keep mashing on 'em till it lights up at this point

electrical contacts? hmmm....

let's see who's had their dash apart recently, eh?

thanks guys...

[killian96ss]

I know my switch went bad once and was covered under warranty.
Instead of showing which gear I was in the lights would just flash at me.

Steve

[dualsport]

Wow. Lot's of good information on this site for this problem.

Good work guys! I appreciate your input...

-Blaine

[F9K9]

Keep us posted, Blaine.

[roadrunner]

It isn't necessary to take the dash apart to replace the button switch. It just pops out and the wires unplug from the rear of it.

[dualsport]

just checked with the local dealership. $45.26 and they have the new tc switch in stock. same price as gm direct (b/c of shipping) but w/o the wait. makes it a no brainer, right? i'm still having issues with the 4x4 engaging properly, but if i'm patient i'm always able to get up my driveway in 4wd... the snow is finally melting and we're looking at the first full week above freezing (daytime temps) so 4wd is less and less a necessity... then again... a guys still gotta have fun...

[dualsport]

Here's a weird detail:

The 4wd switch works just fine when it's colder out (less than 20 degrees), but by the time I either warm up the vehicle by driving to/from work, or the regular ambient temp is warmer, the 4wd switch starts having 'issues' again.

I'm at a bit of a loss on that detail. Oil expansion? Hmmm...

[HenryJ]

Did you try resetting the TC? Just curious if that would make any difference.

[dualsport]

yup. reset it last week after reading through some threads- i disconnected the tccm behind the kick panel for a good ten count. and i initially thought *maybe?!?!*... but it quickly began doin' it again.

just a few hours ago i disconnected the battery before lunch (after holding the terminals together for 15 seconds) and put it back together after a couple more hours. then i had to run down the road for a second and tried out the 4wd- nope. but i could almost hear 'something' under the hood? i'm thinking i've got a leak? i'll see if i can get the supervisor out there and stick an ear under the hood while i mash the buttons. or vise versa.

right now the 4lo works but it's tricky getting back into 2 or 4hi. kind of a back and forth deal.

and i ALMOST bought and installed the tc vacuum switch, but got snaggled with work. i just double checked and i really don't have much air coming through the vents while using the hvac, but will replace it anyhows as a preventative measure.

thanks guys. we'll get it just yet, eh?!

[dualsport]

just tried the 'trasfercase codes' quickfix by grounding pin #13 and turning the key to 'on.' didn't show any lights- supposed to mean a good thing, right? (good thing like... no error codes!?) but then again, when i pulled the paperclip from the #13 and turned the key to on, no lights come on that time either. isn't that a quick test of sort sort that's supposed to flass all three led's? i know i watched it flash a few hours ago after i hooked the battery back up and ran an errand. hmmm. i'm signing off. this thing's consuming me and this forum should have a surgeon general's warning. straight up addictive!

-b

[HenryJ]

Check those dry rotted vacuum lines around and behind the brake booster. Also make sure the line to the reservoir in the fender is attached.
You might be on the right track if other vacuum operated accessories are not working properly.

[okaussie]

I found that I had at least two of those lines behind the brake booster were dry and cracked. It caused my SES light to come on and I, too had 4WD problems. When I replaced all of those lines there, including the one to the resevoir (what a pain to get to), my SES light went out immediately and my 4WD works fine.

Mine has 140K miles on it so I am going to change out all the vaccuum lines one at a time til I get them all replaced. Due to the age and miles I think this is a good idea.

Just a thought

Bill

[dualsport]

just a thought on those vacuum lines- in the mornings when i take off for work the pickup is still in 4wd. if i had a leak, wouldn't it lose the pressure over night and revert back to 2hi (in theory). just got me thinking about that after i checked the t-intersection on the *dry & cracked* lines (mine too).

just checkin in and asking questions... thanks guys.

[roadrunner]

Electric-wise if you parked it in 4wd the night before it would still be in 4wd the next morning and vacuum would pick up on start-up. The vacuum drop-off overnight would release the front actuator but the vacuum pick up is quick enough on start-up you wouldn't know it had released overnight. Unless of course the lines are severely leaking. Then it might take a bit to pull back on. I think you'd be having trouble getting it to engage if they were that bad however. Additionally it would still be in 4wd at the transfer case as that requires the encoder motor to change it's position mechanically and loss of vacuum wouldn't affect that.

[dualsport]

Well, its been a long time in coming, but here's another update:

The snow's been on the ground for two weeks already and we're near single digits overnight up here in Fairbanks, so I'm back to using the 4wd to make it up the driveway. And... "Oh ya, my 4wd switch is still 'on the fritz'?!?!" My memory is amazing.

Jacked up the whole rig last night (looking at a different issue- front end play) and tinkered with the switch again. It appears that the wiring in the back of the switch is intermittently making contact and that I'll need to replace it. I can get the LEDs to light up by doing a calibrated wiggle to the wires in the back. Only when the LEDs are lit up can I make the switch operate.

Just thought I'd throw out an update for those who have been helping so far. Thanks guys...