4wd not engaging

T

TheUltimateBohab

New member
hi guys! so the other day i was hill climbing on the edge of some corn fields and went to hit my 4WD and nothing hum... that's odd i thought..... so i tried 4lo and also nothing it went into low range in the trans but no front wheel power luckily my rear diff lock was working fine and got me through the mud and back to the road. I've gone through a few troubleshooting steps its NOT the vacuum i have vacuum at the VSV and it made no difference when i switched the hoses over. i don't how ever have power to both plugs the redish brown has voltage but doesn't send power to the blueish green. i checked the position switch on the transfer case and it had power when pushed. oh and BTW i got a 97 LIMITED with the multi-mode 4WD with the push button 4hi. one thing i did notice is there is NOT two switches on the TC the FSM says there is and others on here said there was but i only got one,but that must not matter tho because before my 4x4 broke i used it every single day without problems for the past two years i've owned my runner... the next step that i plan on doing here shortly is the relay if i do need one does anybody know the part number or where to buy? oh and one thing i thought i should mention is that the runners with the J shift and not the push 4WD DO NOT have a ADD relay, but i think that the push button 4HI style does according to the FSM its on the passenger side it has 6 connectors if i remember correctly... any help would be greatly appreciated!!
 
Register to hide this ad
^^^Seriously, edit that post and break it up. I am sure someone or even myself could help you but I got nothing out of you post. What is it not doing, and what have you tried so far and we can start from there
 
here ill break it up

not engaging 4WD in 4hi or 4 low (transmission does go into low range)

vacuum is working nothing changed when i switched the hoses

theres two plugs on the VSV power to the redish brown none to the greenish blue

checked the transfer case position sensor it has continuity when pushed (if i checked the rite one.)

so in other words my 4WDs not working why? and is there a relay i could check? the FSM says there is on the push button style multi-mode 4WD
 
Last edited:
The reason I asked is because I also had a 97 before and same scenario happened to my runner. I took it to several different shop and replaced many electrical parts then to find out that my actuator was bad.
 
What do you mean it made no difference when you switched the hoses (engine running)? That should have actuated the front diff and locked the front shaft to the wheels even if there was no drive power coming from the TC. If the shaft locks, your diff actuator is good. If it free wheels regardless of which hose has vacuum, it's bad.

I agree the problem is electrical, but I'm a 5-speed guy and I don't know how to troubleshoot the push-buttons. But I believe you also have an electric actuator on the TC and that COULD be your problem.
 
Last edited:
TheDurk said:
What do you mean it made no difference when you switched the hoses (engine running)? That should have actuated the front diff and locked the front shaft to the wheels even if there was no drive power coming from the TC. If the shaft locks, your diff actuator is good. If it free wheels regardless of which hose has vacuum, it's bad.

I agree the problem is electrical, but I'm a 5-speed guy and I don't know how to troubleshoot the push-buttons. But I believe you also have an electric actuator on the TC and that COULD be your problem.
Click to expand...

sorry its been so long kinda been working a lot.
(of course with the engine running) when i switched the hoses it still didn't fully engage into 4WD, but i tried what you said and with the vacuum lines switched the front tires and 4WD shaft where locked in. so the actuators good.

how would i test the TC actuator? on one of the older threads somebody mentioned " 4WD won't engage. The tech's notation was, "Tested 4WD circuit, replaced bad position switch. and than later "4X4 won't engage." The tech's notation said, "Tested 4WD electrical system, found bad transfer engagement switch, replaced switch." are those the same part? maybe that's my problem... i thought i tested that but may have missed something.

could i just install a jumper to bypass the position switches just to test for a bad without doing any damage?
 
TheUltimateBohab said:
sorry its been so long kinda been working a lot.
(of course with the engine running) when i switched the hoses it still didn't fully engage into 4WD, but i tried what you said and with the vacuum lines switched the front tires and 4WD shaft where locked in. so the actuators good.

how would i test the TC actuator? on one of the older threads somebody mentioned " 4WD won't engage. The tech's notation was, "Tested 4WD circuit, replaced bad position switch. and than later "4X4 won't engage." The tech's notation said, "Tested 4WD electrical system, found bad transfer engagement switch, replaced switch." are those the same part? maybe that's my problem... i thought i tested that but may have missed something.

could i just install a jumper to bypass the position switches just to test for a bad without doing any damage?
Click to expand...

I believe you have the system diagrammed here. Everything is controlled by the 4WD ECU.

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/ewdtmc2/ewdtmpdf/ewdsourc/2002/024runne/systemci/0394wd.pdf

As I have zero knowledge of this system, (I'm a 5-speed guy) I would suggest following the FSM procedure here:

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/trvf3am/ot24ssy/insp.pdf

There are a number of position switches on that set-up; they are shown here:

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/trvf3am/traass/comp.pdf
 
Last edited:
I couldn't tell from your post, but are you saying that your vehicle IS going into the lower output of the transfer case gearing, but the front axle is NOT being powered by the vehicle?

This sounds like it could be an ADD issue, but I can't exactly tell from your post...
 
BlackWorksInc said:
I couldn't tell from your post, but are you saying that your vehicle IS going into the lower output of the transfer case gearing, but the front axle is NOT being powered by the vehicle?

This sounds like it could be an ADD issue, but I can't exactly tell from your post...
Click to expand...

yeah i have low range gearing but the front wheels are not getting drive power in 4hi or 4lo. i checked my actuator earlier today using the method the derk mentioned and it locked in meaning its good but no drive power still.
I think I've boiled down it to something electrical been thinkin maybe its one of the position switches. so for my next step i'll just start checking them one by one and see if i can find the culprit. but i must know if i can just unplug them and install a jumper wire without doing damage?

also the reddish brown VSV plug isn't sending power to the green plug the other side could that be my problem? just the electrical part of the VSV needs to be replaced? that wouldn't be a bad deal if so cuz that's not super expensive and its really easy to get to...

i may have mentioned this already but it didn't build up to this it worked great the previous day and the next morning it just stopped working out of the blue i dont know if that helps...
 
Which actuator are you referring to?

The ADD is located on the front axle and engages a shift fork to combine the left and right halfshafts and allow power to be transfered to the front wheels via the Transfer Case. The actuator on the transfercase itself engages the 4Hi, 4Lo shift forks and actually creates the split between front and rear axles.

If I am understanding you correctly, you're saying you've tested the front ADD actuator and it engages, but the driveshaft between the transfercase and front axle does NOT spin?
 
BlackWorksInc said:
Which actuator are you referring to?

The ADD is located on the front axle and engages a shift fork to combine the left and right halfshafts and allow power to be transfered to the front wheels via the Transfer Case. The actuator on the transfercase itself engages the 4Hi, 4Lo shift forks and actually creates the split between front and rear axles.

If I am understanding you correctly, you're saying you've tested the front ADD actuator and it engages, but the driveshaft between the transfercase and front axle does NOT spin?
Click to expand...

when not engaged the drive shaft spins freely when i flipped the vacuum hoses around to test the front actuator the drive shaft didn't spin freely in other words it was locked in put the vacuum hoses back to normal and spun free again.
how do i test the actuator on the transfer case?
 
This is a section on troubleshooting the 4WD system for the AT 4Runner with the push button 4WD system from TIS;

View attachment INSP.pdf

This is also the EWD (Electrical Wiring Diagram) from TIS for a '97 4Runner with the electronically actuated 4WD system;

View attachment TR14wdws97.pdf

I would try to follow the FSM testing procedure at this point and see where it takes you; the actuator is a pain to replace and I believe is internally pinned to the transfercase much like the 4th Gens. If you do need to replace it, I would not short-cut the procedure as a couple of people who have done it to their 4th Gens ended up having to replace the entire transfercase later as a result.
 

Attachments

Did you ever figure out why you were not getting 12v to the blue green VSV?? Im having the same issue on a 97 limited truck with the push button 4wd on the shifter stick.. I can trick the truck into 4wd by swapping the vac lines so all the wheels pull, but the VSV to ENGAGE isnt getting 12v..
 
spooled91t said:
Did you ever figure out why you were not getting 12v to the blue green VSV?? Im having the same issue on a 97 limited truck with the push button 4wd on the shifter stick.. I can trick the truck into 4wd by swapping the vac lines so all the wheels pull, but the VSV to ENGAGE isnt getting 12v..
Click to expand...

I had the same problem a while back on my 5-speed. No power to blue VSV. It turns out the transfer case switch wasn't working. The switch is normally open and when closed, signals the cpu, which in turn switches power from brown to blue VSV. I think it is similar on the push button system, but not sure. The answer is out there, just gotta search, but hopefully, this puts you on the right track.
 
Ha.. been searching all day and this is by far the most closely related scenario to what im seeing on this truck.. all the other threads usually blame the actuator but since i can trick the actuator into working and 4wd works, i know its electrical.. ill have to check that TC switch in the morning.. Guess i need to read up on how to find and fix it.. Thanks man!
 
Rehashing an old thread but I can't find an answer anywhere...

My 2001 SR5 just replaced tcase and 4wd hi won't engage unless I throw car into reverse. Lights blink in park and while driving. Any idea how to get normal 4wd engagement?
 
You must log in or register to reply here.

Members online

Total: 288 (members: 1, guests: 287)

Forum statistics

Threads
278,309
Messages
3,554,068
Members
248,016
Latest member
Advally Service

Share this page

Trending content

Back
Top