Trouble shooting 4wd

[LoneStarr]

So I figure I will let yall see my troubleshooting process for my 4wd problem. Truck is a 1998 T4R with j shift

I have no indicator light coming on. It does not come on before I start the vehicle. Not sure if that is normal.

Checked fuse, swapped with working wiper fuse. Still no luck.

Swapped vacuum lines on VSV (not 100% sure I'm switching the right lines). No change.
I did just notice that it seems like it is missing a cap on one of them. In service manual one picture has a cap on each and another does not. I have included pictures.

Waiting on buddy to bring vacuum gauge over and test light. Will get the vehicle jacked up and check switch at TC and actuator with vacuum gauge.

I have read multiple thread and they are leaving me a bit confused so if yall have any advice I would love to hear it.

Thanks in advance

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[mesooohoppy]

edit: please disregard, im an idiot.

 

[LoneStarr]

98s never came with a j shift xfer case from the factory. it started with 99 limiteds. did you swap out the x fer case at some point in time?

I didn't. I just got the vehicle.

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[brillo_76]

98s never came with a j shift xfer case from the factory. it started with 99 limiteds. did you swap out the x fer case at some point in time?

Hmm. If they never did. I in trouble as 2 of my 1998 are J shifter transfer cases. Only the limited didn't have ths J shifter. The non limited do.




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[brillo_76]

My 98 4wd switch is sticking. 98% of the time I put it in 4 it will not light be 4wd is functioning.

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[phattyduck]

98s never came with a j shift xfer case from the factory. it started with 99 limiteds. did you swap out the x fer case at some point in time?

J-shift refers to the fully manually shifted standard transfer case found in all base and SR5 models from '96-'00. He has the normal setup. Limiteds either have an electronically shifted 4WD case ('96-'98) or a multimode case ('99-'02 Limited, '01-'02 SR5).

-Charlie

 

[LoneStarr]

My 98 4wd switch is sticking. 98% of the time I put it in 4 it will not light be 4wd is functioning.

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I checked to see if it was functioning by getting partially stuck and seeing what wheels were spinning. Only the rear was

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[phattyduck]

So I figure I will let yall see my troubleshooting process for my 4wd problem. Truck is a 1998 T4R with j shift

I have no indicator light coming on. It does not come on before I start the vehicle. Not sure if that is normal.

Checked fuse, swapped with working wiper fuse. Still no luck.

Swapped vacuum lines on VSV (not 100% sure I'm switching the right lines). No change.
I did just notice that it seems like it is missing a cap on one of them. In service manual one picture has a cap on each and another does not. I have included pictures.

Waiting on buddy to bring vacuum gauge over and test light. Will get the vehicle jacked up and check switch at TC and actuator with vacuum gauge.

I have read multiple thread and they are leaving me a bit confused so if yall have any advice I would love to hear it.

Ok.... your 4WD system is pretty simple.

The missing cap is just a filter for the VSV (vacuum switching valve) and shouldn't cause an issue short term. A small amount of air gets sucked in that open port when the VSV releases vacuum. Likely this is not your issue, though you may want to get replacement VSVs in the future.

Do you get a click in the passenger kick panel when you shift from 2WD to 4WD? (key ON)

If you don't, you have a problem with the 4WD indicator switch on the transfer case. That switch activates the ADD relay in the passenger kick panel (click!) that then swaps power between the two VSVs you have in your picture. This swaps vacuum on the ADD actuator on the front diff. When the actuator moves, it activates the ADD indicator switch on the front diff, which then turns on the 4WD light on the dash.

If you do get the click, check that 12V power changes from one relay to the other at those two plugs.

It is also possible that the ADD indicator switch at the front diff isn't working, but you actually are in 4WD. Does the drivetrain bind when you have the shift lever in 4WD?

-Charlie

 

[LoneStarr]

Ok.... your 4WD system is pretty simple.



The missing cap is just a filter for the VSV (vacuum switching valve) and shouldn't cause an issue short term. A small amount of air gets sucked in that open port when the VSV releases vacuum. Likely this is not your issue, though you may want to get replacement VSVs in the future.



Do you get a click in the passenger kick panel when you shift from 2WD to 4WD? (key ON)



If you don't, you have a problem with the 4WD indicator switch on the transfer case. That switch activates the ADD relay in the passenger kick panel (click!) that then swaps power between the two VSVs you have in your picture. This swaps vacuum on the ADD actuator on the front diff. When the actuator moves, it activates the ADD indicator switch on the front diff, which then turns on the 4WD light on the dash.



If you do get the click, check that 12V power changes from one relay to the other at those two plugs.



It is also possible that the ADD indicator switch at the front diff isn't working, but you actually are in 4WD. Does the drivetrain bind when you have the shift lever in 4WD?



-Charlie

Thanks for the reply.

I am not getting any click and it does not feel any different when I switch to 4wd. I got partially stuck to see if it was working and only the rear wheel was spinning.

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[phattyduck]

Thanks for the reply.

I am not getting any click and it does not feel any different when I switch to 4wd. I got partially stuck to see if it was working and only the rear wheel was spinning.

Start with that 4WD indicator switch.

Use the google advance search like this: Alternate Search for T4R - 3rd Gen Section and get to researching!

-Charlie

 

[thennen]

Some of the best fun I have on this forum is this stuff - watching people help each other troubleshoot. I learn quite a bit myself. This forum is great for this!

 

[mesooohoppy]

I didn't. I just got the vehicle.

im an idiot, please disregard. i will see myself out now.

J-shift refers to the fully manually shifted standard transfer case found in all base and SR5 models from '96-'00. He has the normal setup. Limiteds either have an electronically shifted 4WD case ('96-'98) or a multimode case ('99-'02 Limited, '01-'02 SR5).

-Charlie

thank you. see above.

 

[LoneStarr]

Start with that 4WD indicator switch.



Use the google advance search like this: Alternate Search for T4R - 3rd Gen Section and get to researching!



-Charlie

Should both VSV's being getting power? At all times?


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[LoneStarr]

So I figured out if I unplug one of the VSV it will go into 4wd. The indicator light works also. I did get myself stuck in my yard testing it though (still waiting on new tires) haha.

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[brillo_76]

edit: please disregard, im an idiot.

We all make mistakes mesooohappy. Don't be too hard on yourself no biggie..

 

[brillo_76]

So I figured out if I unplug one of the VSV it will go into 4wd. The indicator light works also. I did get myself stuck in my yard testing it though (still waiting on new tires) haha.

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Oh great Progress. Your light and switch are working. Which one did you unplug?

 

[LoneStarr]

Oh great Progress. Your light and switch are working. Which one did you unplug?

The VSV2 I believe

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[phattyduck]

Should both VSV's being getting power? At all times?

No, only one VSV will have power at a time. Based on my '97 diagrams (should match your '98, hopefully!), the green wire at the VSVs should have power in 2WD and the Purple-Green wire should have 12V in 4WD. White-Black is ground (and almost always is with Toyota).

Since the ADD relay isn't clicking, it is still likely the switch on the transfer case.

You can also test at the ADD relay with a multimeter (leave ADD relay plugged in, truck on):

Black-Yellow (2 wires): 12V power to relay and relay coil
Green: Power to "2WD" VSV (12V 2WD, low voltage 4WD)
Purple-Green: Power to "4WD" VSV (12V 4WD, low voltage 2WD)
Green-Red: from 4WD indicator switch on transfer case, ~12V in 2WD, ground in 4WD.

With the truck off, you should also be able to use the 'continuity' mode of the multimeter to see if the Green-Red wire at the ADD relay shorts to ground with the shifter in the 4WD position.

Wire colors did change year-to-year so hopefully TheDurk can check my info...

-Charlie

 

[TheDurk]

Should both VSV's being getting power? At all times?


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Only one VSV gets power. It switches from one to the other as you go into and out of 4x4.

Looks like no changes between Charlie's '97 and your '98. '98 attached:

 

[LoneStarr]

No, only one VSV will have power at a time. Based on my '97 diagrams (should match your '98, hopefully!), the green wire at the VSVs should have power in 2WD and the Purple-Green wire should have 12V in 4WD. White-Black is ground (and almost always is with Toyota).



Since the ADD relay isn't clicking, it is still likely the switch on the transfer case.



You can also test at the ADD relay with a multimeter (leave ADD relay plugged in, truck on):

Black-Yellow (2 wires): 12V power to relay and relay coil

Green: Power to "2WD" VSV (12V 2WD, low voltage 4WD)

Purple-Green: Power to "4WD" VSV (12V 4WD, low voltage 2WD)

Green-Red: from 4WD indicator switch on transfer case, ~12V in 2WD, ground in 4WD.



With the truck off, you should also be able to use the 'continuity' mode of the multimeter to see if the Green-Red wire at the ADD relay shorts to ground with the shifter in the 4WD position.



Wire colors did change year-to-year so hopefully TheDurk can check my info...



-Charlie

I really appreciate you taking the time to help me with this.

So I am getting power at both VSV at all times. I found if I unplug one I can get it into 4wd. I will be doing some more troubleshooting when I get some time.

Thanks again

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