Wanderlust4
New member
Ok, so I’m having 4WD issues on my 99 Limited with the Multi-Mode 4WD system and an E-Locker. Long post ahead, so I apologize in advance.
Problem: Every so often, the 4WD light on the dash will start blinking on its own with no input. I usually leave it in 2WD. As I’m driving around in 2WD, sometimes, the light on the dash will randomly start blinking. Once the light starts blinking, none of the AWD button or the J gate shifter will work/I can’t get it to actually engage AWD/4WD until the light stops blinking. There isn’t a set amount of time that the light blinks for, it can blink for anywhere from 30 seconds to 30 minutes, and anywhere in between. Eventually, with enough driving, the blinking goes away and I can engage 4WD again. This can happen in any weather, dry, wet, cold, hot.
The blinking isn’t limited to once per week or per day or per drive or anything like that. Sometimes, it won’t blink for several days straight (I commute in the 4Runner most every day), sometimes, it’ll blink once per drive, but I’ve also done road trips where it will blink for a bit, stop, then an hour or two later, start blinking on its own again.
I have also been in H4L on the trail, and it was working fine until the light started blinking at me with no input as well. I left it in H4 and the light eventually stopped blinking on its own.
Sometimes, when I press the button to activate AWD, the light will blink as expected, but it won’t go into AWD. Unpressing and repressing the button won’t get it to go. I’ve tried both situations where I left it in AWD and it eventually shifts into AWD and stops blinking as well as putting it back in 2WD and sometimes the light will stop blinking while other times, it will continue until it decides to stop on its own.
The headache is that it is intermittent, with no way to consistently replicate the issue. When the issue is happening, 4WD doesn’t work, but otherwise, it works and locks and shifts from 2WD to 4WD just fine.
My thought is that, effectively, the computer thinks that at least one of the inputs that allow it to determine the state of the 4WD system doesn’t match what it expects. I’ve read through a lot of 4WD issue threads, including the entire 20-some odd pages of the 4WD thread over at Yotatech and haven't really found anything with all the same symptoms. I've done a bit of diagnosis and testing and here's what I found.
Tests done when the issue is happening:
My buddy and I backprobed the ECU to test voltage at the pins associated with the 4WD system. The following table is the results in 2H, AWD, H4L, N and L4L when each state is working as intended:
When the lights are blinking and the system won’t shift in or out of 4WD, we found the following (yellow are the abnormal results):
We also tried testing the VSV under the hood, though I don't know if we followed all the correct procedures. Results:
The shop also tested the VSV. I don’t quite remember what they did because I didn’t write it down then (and that’s my bad). The shop said that the VSV system and front differential are working as intended.
I didn’t test the E-Locker system as I assume that is separate from the transfer case and front differential. It locks fine when in 4L.
The shop went down Toyota’s VF3AM inspection procedure. The 2-4 selector switch continuity passed inspection. The actuator limit switch continuity passed the test. After further tracing, the shop said that the actuator resistance test failed. When measuring the resistance between terminals 2 and 3 and body ground, it apparently is showing 0 ohms. The inspection procedure states that “if resistance value is not specified, replace the actuator assembly”.
So this is where I’m at. I found a few posts and allusions of people pulling apart the actuators and cleaning them, but I haven't found any good DIYs but plenty of warnings on springs popping out and gears needing retiming. Before I go get another transfer case (cheaper than buying a new actuator), are there any other things I should test or possibilities that I might have missed? Do you 4WD gurus here have any other thoughts or suggestions?
Problem: Every so often, the 4WD light on the dash will start blinking on its own with no input. I usually leave it in 2WD. As I’m driving around in 2WD, sometimes, the light on the dash will randomly start blinking. Once the light starts blinking, none of the AWD button or the J gate shifter will work/I can’t get it to actually engage AWD/4WD until the light stops blinking. There isn’t a set amount of time that the light blinks for, it can blink for anywhere from 30 seconds to 30 minutes, and anywhere in between. Eventually, with enough driving, the blinking goes away and I can engage 4WD again. This can happen in any weather, dry, wet, cold, hot.
The blinking isn’t limited to once per week or per day or per drive or anything like that. Sometimes, it won’t blink for several days straight (I commute in the 4Runner most every day), sometimes, it’ll blink once per drive, but I’ve also done road trips where it will blink for a bit, stop, then an hour or two later, start blinking on its own again.
I have also been in H4L on the trail, and it was working fine until the light started blinking at me with no input as well. I left it in H4 and the light eventually stopped blinking on its own.
Sometimes, when I press the button to activate AWD, the light will blink as expected, but it won’t go into AWD. Unpressing and repressing the button won’t get it to go. I’ve tried both situations where I left it in AWD and it eventually shifts into AWD and stops blinking as well as putting it back in 2WD and sometimes the light will stop blinking while other times, it will continue until it decides to stop on its own.
The headache is that it is intermittent, with no way to consistently replicate the issue. When the issue is happening, 4WD doesn’t work, but otherwise, it works and locks and shifts from 2WD to 4WD just fine.
My thought is that, effectively, the computer thinks that at least one of the inputs that allow it to determine the state of the 4WD system doesn’t match what it expects. I’ve read through a lot of 4WD issue threads, including the entire 20-some odd pages of the 4WD thread over at Yotatech and haven't really found anything with all the same symptoms. I've done a bit of diagnosis and testing and here's what I found.
Tests done when the issue is happening:
- All the standard, start, stop drive forwards, backwards, rock it, turn, put in neutral. Doesn’t stop the blinking and doesn’t allow the 4WD to engage when problem is occurring.
- Tried pressing the AWD button and moving the 4WD lever through 4H, N, 4L and back to 2L. Issue persists.
- Turned the car on and off. Issue persists after car restart. Exception is that sometimes, when I turn the car off when the light is blinking and let the car sit overnight, the next morning, the light will stop blinking. This doesn’t always happen though.
- Tried unplugging the 4WD computer under the driver kick panel. Light stops blinking. Replugging the computer back in, the light starts blinking again.
- All differential and transfer case fluids have been replaced.
- Front switch and the center differential switches have been replaced.
- The 4WD computer has been replaced with a used unit.
- The shop has manually applied a voltage to the diff and it locks and unlocks.
My buddy and I backprobed the ECU to test voltage at the pins associated with the 4WD system. The following table is the results in 2H, AWD, H4L, N and L4L when each state is working as intended:
When the lights are blinking and the system won’t shift in or out of 4WD, we found the following (yellow are the abnormal results):
We also tried testing the VSV under the hood, though I don't know if we followed all the correct procedures. Results:
- Verified continuity from 4WD ECU to VSVs
- VSVs click when voltage is applied
- Sometimes, only when unplugged, stray voltage was visible on the brown VSV control wire when the blue VSV was engaged
- The VSV outputs did not always switch when the 4WD lever was moved
- Plugging in one VSV at a time did not cause the blinking to stop in any 4WD mode
The shop also tested the VSV. I don’t quite remember what they did because I didn’t write it down then (and that’s my bad). The shop said that the VSV system and front differential are working as intended.
I didn’t test the E-Locker system as I assume that is separate from the transfer case and front differential. It locks fine when in 4L.
The shop went down Toyota’s VF3AM inspection procedure. The 2-4 selector switch continuity passed inspection. The actuator limit switch continuity passed the test. After further tracing, the shop said that the actuator resistance test failed. When measuring the resistance between terminals 2 and 3 and body ground, it apparently is showing 0 ohms. The inspection procedure states that “if resistance value is not specified, replace the actuator assembly”.
So this is where I’m at. I found a few posts and allusions of people pulling apart the actuators and cleaning them, but I haven't found any good DIYs but plenty of warnings on springs popping out and gears needing retiming. Before I go get another transfer case (cheaper than buying a new actuator), are there any other things I should test or possibilities that I might have missed? Do you 4WD gurus here have any other thoughts or suggestions?
Attachments
Last edited:
