4x4 issue

Goran · 07-14-2008, 11:39 AM

went to put it in 4x4 - 4 hi on the weekend and the light would only blink, it wouldn't stay lit up...

wouldn't switch back to 2hi, but it would just keep blinking at 4hi?? not sure if it engaged or not, but i didn't want to get stuck and find out...

once i pressed the 2hi button, it would switch back to 2 hi, and light would remain lit... but when i pressed 4hi, it would only keep blinking???

any ideas?

dillon_b12 · 07-14-2008, 01:14 PM

Vacuum lines, vacuum actuator, or encoder motor.

These are a few of the common causes of the symptoms you are talking about.

Vacuum actuator is a rubber diaphragm located under the battery.
Encoder motor is the little motor that attaches to the transfer case.

benjamin86 · 07-14-2008, 01:21 PM

I actually have had that problem twice and I just unhooked my battery overnight and it solved the problem. Dont ask me how but it worked.

benjamin86 · 07-14-2008, 01:21 PM

Not saying that will fix it for sure, but its cheap and easy!

dillon_b12 · 07-14-2008, 01:23 PM

Quote: Originally Posted by benjamin86

I actually have had that problem twice and I just unhooked my battery overnight and it solved the problem. Dont ask me how but it worked.

This is a solution for when the encoder motor screws up. I found that it is very easy to confuse the encoder motor if you get to hitting buttons too fast. Resetting the computer clears everything out but you do have to leave it unhooked for several minutes.

If it still doesn't work after you do this, the encoder motor is not your problem.

MikeInCtown · 07-14-2008, 05:13 PM

Aside from the battery, a new 4x4 switch is the next cheapest to replace and is easy to test. Not usre if you have a 3 button or 4 button but they are cheap on eBay. (paid $.99 plus a few bucks shipping for my 4 button)

ZR2nut · 07-20-2008, 08:25 PM

Check the vacuum lines right around/behind the brake booster.You should see them pretty easy.There is a t-fitting.The small vacuum line on mine was dry rotted and had split so there was no vacuum in the system to activate the 4 wheel drive.Also check the actuator under the battery.Sometimes they go bad or the vacuum line to it may be rotted and split.Hope this helps.

MoTruck · 07-20-2008, 11:03 PM

I would start with the vacuum lines. They are the easiest to check. I just went through this on my 99 Jimmy. They were very dry rotted at the T connectors that were mentioned above. I replaced all of these lines and now it works very quickly. I hope this helps.

XtremeBowtie · 07-29-2008, 11:47 PM

My 00 Blazer did the same thing. I just hit 4Hi and put it in reverse and it locked. Then I tried 2HI-4LO... everything works great.

96SSS10 · 08-25-2008, 02:18 AM

Ok, I replaced the actuator, and all the vacuum lines, and the switch on the case. I really wanted to drive it so I took off the encoder motor, put the truck in neutral, then switched it into 2wheel drive with a wrench.

Must the the motor right???

Is there a good way to test the thing before I go and spend a leg on a new one?

Goran · 10-20-2008, 05:33 PM

What size are the vacume lines?

07-14-2008, 11:39 AM	#1
Goran Registered User Join Date: Apr 2006 Posts: 191 Location: Ontario User is: OffLine	4x4 issue went to put it in 4x4 - 4 hi on the weekend and the light would only blink, it wouldn't stay lit up... wouldn't switch back to 2hi, but it would just keep blinking at 4hi?? not sure if it engaged or not, but i didn't want to get stuck and find out... once i pressed the 2hi button, it would switch back to 2 hi, and light would remain lit... but when i pressed 4hi, it would only keep blinking??? any ideas?
	[Reply w/Quote]

07-14-2008, 01:14 PM	#2
dillon_b12 Registered User Age: 23 Join Date: Oct 2002 Posts: 4,254 Location: Kentucky User is: OffLine	Re: 4x4 issue Vacuum lines, vacuum actuator, or encoder motor. These are a few of the common causes of the symptoms you are talking about. Vacuum actuator is a rubber diaphragm located under the battery. Encoder motor is the little motor that attaches to the transfer case.
	[Reply w/Quote]

07-14-2008, 01:21 PM	#3
benjamin86 Registered User Age: 23 Join Date: Nov 2007 Posts: 73 Location: Fort Wayne, IN User is: OffLine	Re: 4x4 issue I actually have had that problem twice and I just unhooked my battery overnight and it solved the problem. Dont ask me how but it worked.
	[Reply w/Quote]

07-14-2008, 01:21 PM	#4
benjamin86 Registered User Age: 23 Join Date: Nov 2007 Posts: 73 Location: Fort Wayne, IN User is: OffLine	Re: 4x4 issue Not saying that will fix it for sure, but its cheap and easy!
	[Reply w/Quote]

07-14-2008, 01:23 PM	#5
dillon_b12 Registered User Age: 23 Join Date: Oct 2002 Posts: 4,254 Location: Kentucky User is: OffLine	Re: 4x4 issue Quote: Originally Posted by benjamin86 I actually have had that problem twice and I just unhooked my battery overnight and it solved the problem. Dont ask me how but it worked. This is a solution for when the encoder motor screws up. I found that it is very easy to confuse the encoder motor if you get to hitting buttons too fast. Resetting the computer clears everything out but you do have to leave it unhooked for several minutes. If it still doesn't work after you do this, the encoder motor is not your problem.
	[Reply w/Quote]

07-14-2008, 05:13 PM	#6
MikeInCtown Registered User Age: 35 Join Date: Feb 2008 Posts: 927 Location: User is: OffLine	Re: 4x4 issue Aside from the battery, a new 4x4 switch is the next cheapest to replace and is easy to test. Not usre if you have a 3 button or 4 button but they are cheap on eBay. (paid $.99 plus a few bucks shipping for my 4 button)
	[Reply w/Quote]

07-20-2008, 08:25 PM	#7
ZR2nut Registered User Age: 43 Join Date: Jul 2008 Posts: 21 Location: Miamisburg,Ohio User is: OffLine	Re: 4x4 issue Check the vacuum lines right around/behind the brake booster.You should see them pretty easy.There is a t-fitting.The small vacuum line on mine was dry rotted and had split so there was no vacuum in the system to activate the 4 wheel drive.Also check the actuator under the battery.Sometimes they go bad or the vacuum line to it may be rotted and split.Hope this helps.
	[Reply w/Quote]

07-20-2008, 11:03 PM	#8
MoTruck Registered User Join Date: Mar 2008 Posts: 3 Location: User is: OffLine	Re: 4x4 issue I would start with the vacuum lines. They are the easiest to check. I just went through this on my 99 Jimmy. They were very dry rotted at the T connectors that were mentioned above. I replaced all of these lines and now it works very quickly. I hope this helps.
	[Reply w/Quote]

07-29-2008, 11:47 PM	#9
XtremeBowtie The Bowtie Brigade Age: 25 Join Date: Sep 2005 Posts: 467 Location: User is: OffLine	Re: 4x4 issue My 00 Blazer did the same thing. I just hit 4Hi and put it in reverse and it locked. Then I tried 2HI-4LO... everything works great.
	[Reply w/Quote]

08-25-2008, 02:18 AM	#10
96SSS10 Winter Projects.... Age: 23 Join Date: Oct 2005 Posts: 139 Location: Youngstown, Oh User is: OffLine	Re: 4x4 issue Ok, I replaced the actuator, and all the vacuum lines, and the switch on the case. I really wanted to drive it so I took off the encoder motor, put the truck in neutral, then switched it into 2wheel drive with a wrench. Must the the motor right??? Is there a good way to test the thing before I go and spend a leg on a new one? Last edited by 96SSS10 : 08-25-2008 at 02:19 AM.
	[Reply w/Quote]

10-20-2008, 05:33 PM	#11
Goran Registered User Join Date: Apr 2006 Posts: 191 Location: Ontario User is: OffLine	Re: 4x4 issue What size are the vacume lines?
	[Reply w/Quote]