NP 229 Transfer Case

[per1277]

I have a foreign made SUV that uses the Jeep Transfer Case NP 229. The vacuum motor is probably not working. Can anyone advise me how I can tell if my transfer case is working? Can I remove the vacuum motor assembly and try to engage the transfer case by pulling or pushing on the lever?? I don't really want to spend $ 250.00 on a new vacuum assembly if my transfer case is INOP. Thank and Regards.

[tgreese]

No personal experience with the 229.

The service manual for 1989 is here: https://oljeep.com/edge_parts_man.html Suggest you download it and read it on your desktop. The NP229 is covered at page 2-281.

Looking at the book, there is a manual shifter for low range, and a vacuum shifter between 2WD and 4WD. Looks like you can remove the vacuum motor and move the shift rod between 2WD and 4WD.

Looking at the Owner's Manual (also on that site), it appears that, in high range, you can select between 2WD or full-time 4WD. In low range, only locked 4WD is provided.

There is an indicator light for 4WD that should indicate the 2WD-4WD shifter action. I would start there, and see if the switch on the transfer case is being activated. I would also expect to see the actuator rod move. The best test would be to put the transfer case in 4WD low range, with the wheels off the ground, and test that the front and rear driveshafts are locked together.

[per1277]

Thank for your input, although some is above my pay grade.

[tgreese]

Which part?

[devildog80]

Nothing is above our pay grade when we own these trucks, just need to process the expert information we are given, then put it into practice. Admittedly some info took me awhile to roll around in my head to understand, but I eventually got it so hang in there, as your promotion will come soon too.

As I pointed out in another of your post, I think on another site, check all the little vac lines as they age badly and become very brittle, breaking easily when we get fussing with other things around them.
I started with the vacuum ball under the hood, finding my pretty color coded 4x4 vac lines are shot, near turning to dust in my hands. But the NP229 works from constant vac from the vac ball on the firewall to the dash selector. When you select 4x4 mode, it should activate the front axle vac solenoid first, then that allows vac back to transfer case vac solenoid. If you have no vacuum to the transfer case, the 4x4 low shift lever next to drivers seat will NOT allow you to move it.
So check all the tiny lines, replace what needs replaced, then check the vac solenoids on front axle and transmission, to be sure they are working freely. There are several write ups on this to Google and expand your pay grade.

I searched Google using this, and popped up with a bunch of threads in about 2 seconds -
shifting the NP 229 Transfer Case

[per1277]

Thanks, first I want to see if the transfer case works, then I'll see how to get the vacuum setup working. Any idea on getting a vacuum motor for less than $ 250.00?
Thanks

[tgreese]

Thanks, first I want to see if the transfer case works, then I'll see how to get the vacuum setup working. ...

You don't see some problem with this statement? Maybe you should realize that the shifter has to work to test 4WD? I described how to go about testing for 4WD. This vehicle is not a Jeep, but the transfer case should have a place for the 4WD indicator light switch. Suggest you start there. Then try to move the shifter by hand.

Likely there is a mechanic out there that can test this transfer case for you, if you can't or won't test it yourself. You either do the work needed, or pay someone to help you. Where are you located? Exactly what kind of vehicle is this? Do you have the manufacturer's service book?

[per1277]

The vehicle is called a Laforza. The service manual says to supply vacuum to the vacuum motor while rotating the rear drive shaft to see if the 4 wheel drive engages. However, the lever does not move regardless of vacuum, most likely because the vacuum linkage itself is not allowing the lever to pull out ( I assume the lever is pulled toward the vacuum pod). This leads me to believe that either the Transfer Case lever is stuck or the vacuum motor is not working. Is my thinking correct?

[devildog80]

X2 what tgreese pointed out.

The front axle vacuum pod must activate first, THEN it will send vacuum back to the transfer case, which will allow the shift lever next to drivers seat to move, and you can engage to 4 low. That shift lever WILL NOT MOVE, until the transfer case vacuum pod has vacuum.
Test it in sequence - make sure your vacuum lines are good, front axle vacuum pod works, then transfer case vacuum pod. Do some google search and you will find other articles/threads across other 4x4 forums explaining this. Get your TSM, read through the section related to this, so you understand exactly how your truck works. The working order above is how my '84 Jeep Grand Wagoneer w/NP229 works, so advising you to verify if that is the same with your Laforza, using the same transfer case. My guess is it is the same.

[letank]

The vehicle is called a Laforza. The service manual says to supply vacuum to the vacuum motor while rotating the rear drive shaft to see if the 4 wheel drive engages. However, the lever does not move regardless of vacuum, most likely because the vacuum linkage itself is not allowing the lever to pull out ( I assume the lever is pulled toward the vacuum pod). This leads me to believe that either the Transfer Case lever is stuck or the vacuum motor is not working. Is my thinking correct?

If the 4WD or low range has not been used in a while, dirt, road dust and leaking fluids can make the system reluctant to be engaged. The lever inside the cab is an diverter for the vacuum, so you need to take a peek in the engine bay.

Under the hood , in the middle of the firewall , the connectors are visible green and yellow lines fed from the main round ball , connect a vacuum pump to supply vacuum, bypassing the round ball. Sometimes the connectors can get brittle, but at least with a constant vacuum being applied you could listen to a hissing sound.

Where are you located, may a brave soul can take a look!

What about of picture of your 2WD/4WD switch... and the low range lever

[dodgerammit]

You can actually unhook the vacuum actuator from the shift linkage, then try to move the linkage by hand. The 2wd-4wd movement will be small. Like maybe an inch. This will allow you to verify the case is good before diving into the vacuum system itself.

When I was troubleshooting my vacuum system (which stopped working suddenly), I applied vacuum to the actuator manually to see if it would move. At that time, that's when I seen the linkage travel the short distance.

We also have an AMC Eagle wagon with the NP129 (single speed version of the same case). The vacuum actuator seized. I ended up removing it and manually engaging the case by moving the shifter lever out and using some tie wire to lock it in 4x4.

Once you can verify the case will shift in/out of 4wd, you can troubleshoot the vacuum. I dunno how Laforza SUVs make the setup work, but I'd imagine it can't be much different than the system in a FSJ.

https://oljeep.com/gw/vac/GW_vacuum.html

Go to this page. Go down to the 83-84 vacuum 4x4 system. they have a few different schematics and diagrams that show the front axle disconnect version of the system. If yours is doesn't have a disconnect setup, it will be even simpler. Vacuum will go to the 4x4 selector switch, then get split into 2 lines going to the vacuum actuator at the case. Vacuum on one side or the other side will allow the shift from 2wd/4wd.

[rocklaurence]

We spoke on the phone this week and mentioned that my shifter would likely work. It may require lengthening the rods but easy enough to do. For others future reference, my kit can be seen here: https://rocklaurencevintageautoparts.co ... k-or-wagon

[per1277]

Thanks to dodgerammit and everyone for your kind support. As recommended, I disconnected the vacuum linkage and moved it manually toward the pod, and it worked. I actually had to clean the contacts on the 4x4 switch and the 4x4 engaged switch to everything working. Doesn't snow very much in Denver anymore, nevertheless, nice to have it working. You are all very nice indeed. Regards.

[dodgerammit]

Thanks to dodgerammit and everyone for your kind support. As recommended, I disconnected the vacuum linkage and moved it manually toward the pod, and it worked. I actually had to clean the contacts on the 4x4 switch and the 4x4 engaged switch to everything working. Doesn't snow very much in Denver anymore, nevertheless, nice to have it working. You are all very nice indeed. Regards.

Awesome news!

Sounds like it is an electric solenoid style vacuum engagement. The 229 is a full time case, meaning it has a differential in the case allowing wheel speed variances. About once a month, switch it into 4wd in any kind of inclimate weather (aka Rain) and drive it a bit. It won't hurt the case as it's not locked F/R like a part time as long as you keep it in high range.

[per1277]

Yes, the shifting into 4x4 is controlled by a vacuum solenoid. Some of the rest of what you said I didn't really understand. What is F/R?

[dodgerammit]

Yes, the shifting into 4x4 is controlled by a vacuum solenoid. Some of the rest of what you said I didn't really understand. What is F/R?

Okay, so most transfer cases are part time, meaning you can't use them on dry pavement or daily because they are locked Front to rear (F/R) when engaged. If you grab the rear driveshaft and turn it, the front will turn at the same rate. Now imagine that when making a tight turn in a parking lot that is paved. The front wheels will try to tun at the same speed as the rear. this causes the vehicle to lurch violently. That is a condition called crow hopping.

A full time 4wd system (some call it awd) uses a differential in the transfer case. Some differentials are open (NP128, NP228, NP242 cases). Some are limited slip (NP129, NP229, NP249). Either way, they allow the front and rear (F/R) wheels to spin at different rates. Kinda like a differential in a rear axle does when going around turns. The outside wheel will travel farther than the inside wheel. If the wheels are locked together (Locker or spool), this can cause unruly behavior on the street.

So, in short, you can engage 4wd high on yours and drive it on dry pavement without issue or fear of damaging anything.

[per1277]

I guess I'm more confused. Laforza's are not full-time 4X4, like say a Subaru. I always thought that on a part-time 4X4 vehicle, you should not operate on dry services?

[tgreese]

I guess I'm more confused. Laforza's are not full-time 4X4, like say a Subaru. I always thought that on a part-time 4X4 vehicle, you should not operate on dry services?

Yes, a full-time transfer case, like a Subaru, can operate in four wheel drive 4WD on pavement.

The NP229 is a full time transfer case. It operates in either two wheel drive 2WD powering only the rear wheels, or full-time 4WD, powering all four wheels. The vacuum motor switches between these modes.

You are posing a contradiction. Either the Laforza can run as full time on pavement, or it's not equipped with an NP229. There is also an NP209, which is a part-time case like you are imagining. However, the NP209 has a shifter only - no vacuum control.

[dodgerammit]

I guess I'm more confused. Laforza's are not full-time 4X4, like say a Subaru. I always thought that on a part-time 4X4 vehicle, you should not operate on dry services?

https://www.awdwiki.com/en/laforza/

[dodgerammit]

Wanna get even more confused? The case in my Jeep now is the NP242. It is a part time AND full time case, offering 2wd, Locked 4wd HI, full time 4wd (open center differential), and Locked 4wd Low.

In the case of the 229, the (limited slip) center differential allows full time use in high range. Drive with 4wd high engaged on any surface, any time. Not gonna hurt it.

As stated before, our AMC Eagle has the 129 case (single speed version of the 229, just no low range). It is permanently engaged due to a failed vacuum actuator. I drive it whenever, wherever. It doesn't care. It's not gonna damage it. It has a center differential.