shaft

I have no power transfered to the front axle when I put the truck in 4 hi or 4 lo. I can feel the gears in the transfer case engage but no power to the front axle. No 4x4 light in the dash either.

Is this an electrical issue? What should I check for? Pls advice. thanks.

ericg

it most likely is the acuator. It's on backside of the pass side axle tube on. It's a vacumn can that throws a fork inside the tube to engage the axle. I got mine on e-bay just search front axle actuator,cost about $80 but saw them in LMC for $107. Took about 45min to change not too technical

Purplezr2

I would remove the actuator and see if it moves my hand, it should move freely. If it does then I would make sure you have vacuum, there is a connector on the top of the T case, make sure its seated properly. Easy way to see if you have vacuum is to climb under the truck with it running(in park and Pbrake on) and you will see a red and black line coming off the Tcase they go to a pair of metal lines. You can remove them and see if they will make the actuator move. if they don't I would say you have an issue with the vacuum switch at the T case or no vacuum to the T case.

Tallguy67

When I got my truck a few months ago there was not 4x4 or light. Checked and the transfer case was working fine. That meant it was the CAD on the passenger side of the front axle. After the same recommendation from many people here, I ditched the vacuum actuated CAD and got a manual one from Posi-Lok. The vacuum actuated CAD is a really weak design on these trucks. Have you seen the vacuum lines - they are capillary tubes andthey are down under the truck where they can get physical abuse as well as rust/corrode really easily. The Posi-Lok cost about $200 and took about 2 hrs to install. Everything worked and fit perfectly straight out of the box. Now when I need 4x4, I pull the cable, the light comes on, engage the transfer case and voila, 4x4. No questions, no weak CAD or vacuum lines waiting to fail. Yes, this is a pretty big endorsement for the Posi-Lok actuator - it went in easy and just works.

torquefan

First thing you should do is check the vacuum to the front axle disconnect. Idling in 2WD, you should have good vacuum (over 15") on one line, then when you shift it to 4WD the vacuum should switch to the other line.

Busboy

I agree, check the vacuum first. Lines often become disconnected or leak.

Luckyrogue

I agree as well with the vaccuum check. A couple years back my axle wasn't engaging so I crawled under the truck and pulled the lines off at the actuator and had my wife shift it into 4x4, no vaccum on one line. I followed it back and right on the skid plate where they ran there was a joint, pulled the lines there and I had vaccuum to both lines. I then just ran a new rubber line along side of the old one and have had 4x4 ever since. The new rubber line only cost a few dollars as well, cheap fix. Good luck

shaft

Thank you for all for great response. This is great.

Pardon my ignorance but how do you check for the vacuum? What tool do i need for that? Thx.

rebal

with the engine running pull the line at the cad then put your finger on it you should feel a light sucking on the lines

Busboy

First look up high on the firewall drivers side just below the hood seal you will see some vacuum lines, ensure these are connected as it's easy to disconnect them at this spot when rummaging around under the hood. Ok then next check the CAD (axle disconnect) ensure that the vacuum lines are still connected. If these are good then I would start it up and disconect the vacuum line at the spot on the firewall, you can tell if you have vacuum by placing your finger over the end of the line and you should feel it sucking, if the engine wasn't so noisy you could also hear it. If there is no vacuum there then the other bad spot is below the driver side battery, the acid rots the rubber and they can leak there. You can just cut out the bad spot and splice it back together if you don't want to replace the whole thing. If you have no vacuum you will have no cruise or heater mode controls.

shaft

I have not had the time to go under the truck and check things out. However I drove the truck this morning and I have cruise and heater mode controls. So I have some vacuum. Is this the same vacuum system that controls the
4X4 ? Can we rule out the vacuum issue at this point? I will still check for leaks and the other suggestions regardless.

Busboy

You can "almost" rule out vacuum. You should get under and look at the CAD (Axel disconnect) and ensure that the vacuum fitting is installed correctly. hopefully it's not and that is your problem. Failing that you will need to go to the Xfr case vacuum control sw to check for vacuum. WAIT! you did look at the firewall vacuum fittings didn't you?? This is the first point of checking as it's the most common place for vacuum disconnection. You could possibly still have enough vacuum for the other functions. The CAD uses quite a large volume of vacuum compared to the heater modes. The cruise uses quite a bit too but is closer up line from the CAD.

shaft

Finally had the chance to crawl under the truck and the checked for vacuum and the connectionns. Vacuum is good -- I had the wife shift the truck to 4 wheel drive and I have good vacuum on both lines. I did this on the axle and the t-case. Also check the rest of the connections and everything is good.

Now is it safe to say that the actuator needs to be replaced? I did not have time to remove the actuator to see if it moves freely. I think I will do that first before I order a new actuator just to confirm. Once removed, how do I know that it's bad if it moves freely? What should I check for?

The cheapest actuator I can find is in eBay for $68 with free shipping. Is that a good price?

ericg

yep thats a good price the original part was made by dorman,so if the replacement is also a dorman your in good shape. When you pull the housing off your gonna lose a little gear oil so have a pan ready. Also your gonna need to take the actuator fork off the old one and put it on the new one,just pay attention to the way it's oriented,as is is curved. All in all pretty straight foward install. Think it took me less than an hour.

shaft

Thank you all for the great help. I was able to replace the actuator with a new one from ebay ($68 free shipping). Intallation was very easy. Took about 45 mins. The old actuator was stuck -- probably the original one. I'm ready for the snow again.