SOLVED - Help troubleshooting 4WD issue for '00 with j-shifter

cl4Rk

cl4Rk

Member
UPDATE: see post #11 (reply #10) below: https://www.toyota-4runner.org/3688745-post11.html

2000 SR-5 auto with J-shifter 4WD. My 4WD HI and LO worked normally (correctly) before the frame swap.

Current Situation:
- My front wheels are not getting power when I shift into 4WD (HI and LO) (no binding or wheel chirp on pavement).
- I do hear the actuator click
- I do see the 4WD dash light illuminate at the appropriate time.
- I do shift into the low gears (slow moving, high revving) when in 4LO.

Things I've already checked:
- The front propellor shaft spins freely while in 2WD.
- The front propellor shaft locks up and does not spin freely while in 4HI and 4LO.
- The frontmost VSV hose has vacuum while in 2WD.
- The rearmost VSV hose has vacuum while in 4HI and 4LO.
- Switching the VSV hoses prevents the 4WD light from illuminating at all (and does not send power to the front wheels), suggesting the hoses are currently in the correct places.

Question:
What's my next step in troubleshooting this?

New cv axles go in soon, the truck will be up on a lift. Thanks!!
 
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Sounds like your tcase is doing what it needs to do but maybe not the ADD system. The fact that the front driveshaft is locking up when in 4HI or 4LO suggests this. Since you have an open diff if the ADD doesn't kick on then it will just send the power to the disconnected stub shaft.
 
Since the front driveshaft is locking/unlocking then your transfer case is operating as designed.
Your VSV and relay are working correctly since vacuum is switching.
I would check the vacuum lines from the VSV to the ADD actuator. Some people have had disconnected/broken/damaged vacuum lines causing the ADD actuator to not move/engage. If you have a hand vacuum pump (Amazon.com: Mityvac MV8000 Professional Single Person Manual Brake and Clutch Bleeding Tune-up Kit : Automotive) you can also actuate the ADD system yourself to make sure the actuator is functioning properly.
 
If the dash light is illuminating then the actuator in the front diff is working. How are you determining you are not getting power in the front? Sounds like something mechanical in the front diff if it is indeed not working.
 
JustTroItIn said:
If the dash light is illuminating then the actuator in the front diff is working. How are you determining you are not getting power in the front? Sounds like something mechanical in the front diff if it is indeed not working.
Click to expand...
Unless the wires are shorted - which can happen from mechanical damage during engine/frame/body installs. The front indicator switch is on its own little harness that can be missed and/or damaged.

-Charlie
 
JZiggy said:
Sounds like your tcase is doing what it needs to do but maybe not the ADD system. The fact that the front driveshaft is locking up when in 4HI or 4LO suggests this. Since you have an open diff if the ADD doesn't kick on then it will just send the power to the disconnected stub shaft.
Click to expand...

Bad Luck said:
Since the front driveshaft is locking/unlocking then your transfer case is operating as designed.
Your VSV and relay are working correctly since vacuum is switching.
I would check the vacuum lines from the VSV to the ADD actuator. Some people have had disconnected/broken/damaged vacuum lines causing the ADD actuator to not move/engage. If you have a hand vacuum pump (Amazon.com: Mityvac MV8000 Professional Single Person Manual Brake and Clutch Bleeding Tune-up Kit : Automotive) you can also actuate the ADD system yourself to make sure the actuator is functioning properly.
Click to expand...

Looks like my 4WD (blue) ADD solenoid is bad.

Toyota still sells PN 8544035040 which is the whole assembly. Pretty pricey.
Some sources show this part is no longer in production (but dealers seem to still have stock).
Neither NAPA nor RockAuto have anything for this PN.

EDIT: I found Toyota PN 8544035040 used for a decent price. Used OEM with a one-year warranty. I'll update this thread to confirm fix.
 
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Has anyone rebuilt one of these ADD solenoids? (I've watch [MENTION=120071]mtbtim[/MENTION] 's video on rebuilding the starter solenoid.)

The ability to rebuild these would be pretty useful since according to some sources they are no longer in production. Based on my searches, they really don't seem to fail that often, but still.

(Toyota dealers still have these in stock, but I didn't see any new OEM PN 8544035040 for less than about $530).

I know you can also bypass the ADD system: Toyota Tech: Defeating the ADD System
 
cl4Rk said:
Has anyone rebuilt one of these ADD solenoids? (I've watch [MENTION=120071]mtbtim[/MENTION] 's video on rebuilding the starter solenoid.)

The ability to rebuild these would be pretty useful since according to some sources they are no longer in production. Based on my searches, they really don't seem to fail that often, but still.

(Toyota dealers still have these in stock, but I didn't see any new OEM PN 8544035040 for less than about $530).

I know you can also bypass the ADD system: Toyota Tech: Defeating the ADD System
Click to expand...

When/If my ADD dies, I'm going to defeat it, and just bite the bullet on the Tacoma Manual Hub conversion.
 
JZiggy said:
Sounds like your tcase is doing what it needs to do but maybe not the ADD system. The fact that the front driveshaft is locking up when in 4HI or 4LO suggests this. Since you have an open diff if the ADD doesn't kick on then it will just send the power to the disconnected stub shaft.
Click to expand...

This is my thoughts as well
 
SOLVED

Just updating this thread to confirm that replacing the “Solenoid Assembly, Four Wheel Drive Control” (Toyota PN 8544035040) fixed my issue. Even though it was only the 4WD-specific (blue) ADD solenoid that failed, I replaced the whole assembly with a used one that was pulled from a '99 Tacoma.

I kept my old assembly so I can attempt to rebuild the bad solenoid and keep it as a spare.

FYI the official Toyota Parts website and a few other sources say that Toyota PN 8544035040 is no longer in production. About a month ago a few dealers had some in stock for $550-$750, but that new-old-stock now seems to be gone. I paid Japanese Truck Dismantling about $134 for my used Tacoma assembly (which they had cleaned and tested and shipped with a one-year warranty). I also saw a couple assemblies and a couple solenoid-only listings on eBay at various condition levels and price points. What I'm saying is that Toyota PN 8544035040 will only get more difficult to find as the years go by.

If I can successfully rebuild my old unit, I'll document the process in a new thread.

Thank you everyone for all the help!
 
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glad you fixed your issue.
about 2 years back I pulled all the solenoids and everything related including the actuator on the axle... at a pick and pull....now sitting on my shelf if needed.
so guys as cl4Rk pointed out these are getting expensive new if you can find them. so if your in a pick and pull and find them you might want to grab and store it for the future.
 
JustTroItIn said:
I'm a bit confused how you were hearing the actuator and how your dash light was illuminating if your VSV was bad.
Click to expand...

I am too, honestly.

I thought the actuator would only click if it was getting the correct vacuum.

And I thought that the 4WD dash indicator light would only turn on if the front differential was reporting back that everything was engaged properly. Given my situation, I'd expect to get no light, or maybe a flashing light. IDK.

Maybe someone here can elaborate?
 
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cl4Rk said:
I am too, honestly.

I thought the actuator would only click if it was getting the correct vacuum.

And I thought that the 4WD dash indicator light would only turn on if the front differential was reporting back that everything was engaged properly. Given my situation, I'd expect to get no light, or maybe a flashing light. IDK.

Maybe someone here can elaborate?
Click to expand...
According to my 2000 EWD the 4wd light needs the ADD position switch and 4wd position switch to be closed in order to complete the ground circuit. Is it possible you have a faulty add position switch?

Here's the diagram: Dropbox - 2000 4Runner Electrical Wiring Diagram (EWD383U) - Printable - Simplify your life
 
Bad Luck said:
According to my 2000 EWD the 4wd light needs the ADD position switch and 4wd position switch to be closed in order to complete the ground circuit. Is it possible you have a faulty add position switch?

Here's the diagram: Dropbox - 2000 4Runner Electrical Wiring Diagram (EWD383U) - Printable - Simplify your life
Click to expand...

Thanks for sharing that EWD!

Maybe the ADD Position Switch is faulty, I haven't tested it (yet).

Genuine question, if the ADD Position Switch was faulty, why would the 4WD indicator light behave exactly as it's supposed to from an end-user standpoint? Light off when j-shifter is in H2 position, and light on when j-shifter is in H4 and L4 positions? Or maybe I'm misunderstanding what the switch does.

EDIT: I think I understand. A faulty ADD Position Switch might have been giving me a false positive on the indicator light. If the ADD Position Switch is erroneously closed all the time, then the indicator light will turn on as soon as the 4WD Position Switch is closed. So, it's not that a faulty ADD Position Switch was causing my 4WD not to engage, but rather a faulty ADD Position Switch might cause a reporting error (indicator light on) which served as a red-herring during troubleshooting. If I leave everything in its current state, then everything works from a driver's perspective: 4WD sends power to front wheels, indicator light is on/off at appropriate times. However, the indicator light is actually only reporting on j-shifter position, instead of both j-shifter position and ADD position. Am I on the right track?
 
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cl4Rk said:
Thanks for sharing that EWD!

Maybe the ADD Position Switch is faulty, I haven't tested it (yet).

Genuine question, if the ADD Position Switch was faulty, why would the 4WD indicator light behave exactly as it's supposed to from an end-user standpoint? Light off when j-shifter is in H2 position, and light on when j-shifter is in H4 and L4 positions? Or maybe I'm misunderstanding what the switch does.

EDIT: I think I understand. A faulty ADD Position Switch might have been giving me a false positive on the indicator light. If the ADD Position Switch is erroneously closed all the time, then the indicator light will turn on as soon as the 4WD Position Switch is closed. So, it's not that a faulty ADD Position Switch was causing my 4WD not to engage, but rather a faulty ADD Position Switch might cause a reporting error (indicator light on) which served as a red-herring during troubleshooting. If I leave everything in its current state, then everything works from a driver's perspective: 4WD sends power to front wheels, indicator light is on/off at appropriate times. However, the indicator light is actually only reporting on j-shifter position, instead of both j-shifter position and ADD position. Am I on the right track?
Click to expand...
As far as I understand it you have it correct in your edit. If the ADD switch has faulted into a closed position then once the transfer case position switch closes in 4HI then the circuit for the 4wd light will be complete.
 
Bad Luck said:
As far as I understand it you have it correct in your edit. If the ADD switch has faulted into a closed position then once the transfer case position switch closes in 4HI then the circuit for the 4wd light will be complete.
Click to expand...

Excellent, thank you!

[MENTION=643492]JustTroItIn[/MENTION] so a faulty ADD Position Sensor would explain why I was seeing the indicator light, and the click sound I was hearing was not the actuator but rather a relay, I guess?
 
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So, if I do decide to replace the faulty ADD Position Switch, I think I’d need Toyota PN 8422235110

Can anyone confirm the part number and also which switch it is on the photo below? (I'm assuming the ADD Position Switch in on the transfer case, correct me if I'm wrong. If the body was still off the frame, I'd be able to just following the wires...)

485037635007179e9d4de875fee2de38.jpg
 
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