4×4 not engaging Chevy Blazer 2001

[fcobob78]

Decided to drive my car into the mountains and got decent snow there.

Topic

[EricTheCarGuy]

The first thing to do is check the owners manual as you may not be operating it properly, you may need to put the truck in reverse or neutral before engaging the 4wd so be sure to check and see if you are operating it correctly first by checking the owners manual, it may also give an explanation as to why the light blinks when you try to engage it. Once you do that check back and we’ll see if we can help you if you still have an issue.

[fcobob78]

Hi Eric,

I double checked the Owner’s Manual and was operating it properly. In order to shift to 4LO cars need to be in Neutral at stop or moving at less than 3mph, which is what I was doing. For 4HI, it doesn’t matter, car can be running at any speed. Today I had a buddy watching my wheels, while driving over a small hill on ice and he said the front wheels were not spinning at all. I even switched the 4×4 to neutral hoping to reset things and nothing happened.

Strange thing is, when I switch to 4HI or 4LO I can hear something engaging, but obviously not working. Owner’s manual doesn’t mention what the blinking light means. But I know lit on is normal. There is a Service 4WD light that is NOT coming on, which makes me wonder if it is some sort of cable that might be lose?

Where should I start looking? Also, I brief explanation of 4×4 system operation/components would be appreciated.

Thanks!

[college man]

I take it that by pushing the button you are engaging the 4wd.its not the old linkage type. The light blinking may mean that the the vehicle
is not seeing transfer case engagement. there has to be a motor or something to engage the transfer case. do a visual inspection under the truck
to see if anything is torn or hanging.maybe in your inspection you could put the tuck on jack stands and have someone engage the 4 wd
and you can see what sounds like its trying to engage. good luck and keep us posted. C8-) found this link. it explains a few things

http://www.fixya.com/cars/t639984-2001_ … heel_drive

[dreamer2355]

Great post College Man.

Also, this video may give you a better understanding of a common issue with these vehicles –

http://www.youtube.com/watch?v=stooGR4B … MuyQOLDmqo

[fcobob78]

Thanks for the video. I will check the actuator and cables to make sure everything looks OK there. On another note, see picture attached with red arrows. This hose hanging by itself has me intrigued what is for. Goes underneath the radiator to what it looks like small blower. Pardon my ignorance, but I would like to know what is the function of this hose and if needs to be connected to something. Looks like is some sort of purge line?

[college man]

good question. from the picture I honestly don’t know. you will need to follow the hose up and to where it goes and post back. C8-)

(Thanks dreamer)

[dreamer2355]

That hose may be the drain for the issue (at a guess) but like posted above, just follow the hose to its destination C8-)

[EricTheCarGuy]

It may be a vent hose, I don’t think it has anything to do with the 4WD however. I believe that system uses an electronic servo to engage the front differential and it may also have one on the transfer case, I think the next step would be to get all 4 wheels up off of the ground and activate the 4WD if the driveshaft going to the front diff doesn’t’ engage then I would suspect an issue in the transfer case, if it does then I would narrow my diagnosis to the front differential.

[fcobob78]

Hi Eric. I got my car up on 4 jack stands, but had to shot some videos from underneath with my phone, because I did not have a buddy to switch the 4×4 while looking under. It appears to me from my video that the front drive shaft rotates, but doesn’t engage with the transfer case. However, I’m not sure that I know how to tell this. I just saw the drive shaft rotating normally as it should, but not transferring any torque to the front differential. Front wheels will not rotate at all.

I read some forums online for similar issues and it seems to be that the problem might be the vacuum solenoid. I will try bypassing the solenoid by connecting the vacuum lines and see if this engages the front axle. Will post any updates. In the meanwhile suggestions are welcome.

[fcobob78]

Hello, here is an update. I found the problem. I checked the solenoid valve and sure enough there was a vacuum hose that broke and was disconnected. The vacuum hose was coming from an actuator located underneath the battery. Reconnected and now works like a charm!. However I do need to go back and probably replace the hoses sometime. By visual inspection they show lots of cracks.

Thanks to all you guys that helped me out. You are awesome.

[dreamer2355]

Quoted From fcobob78:

Hello, here is an update. I found the problem. I checked the solenoid valve and sure enough there was a vacuum hose that broke and was disconnected. The vacuum hose was coming from an actuator located underneath the battery. Reconnected and now works like a charm!. However I do need to go back and probably replace the hoses sometime. By visual inspection they show lots of cracks.

Thanks to all you guys that helped me out. You are awesome.

Im really glad you found the issue! Nice job!

And thanks for the update and using the ETCG forums!

[Author]

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