4WD HI Blinking Light

Since buying my 2001, I've sold the toolbox and did a full timing belt service (belts, idlers, water pump, fan mount, etc.) Now I need to get the 4WD working before any serious snow (we've got 3"-5" coming Tuesday, not going to happen before then).

My truck won't go into 4WD low, best I can tell. I've read a bunch of threads and think I have a path to fix it, but wanted to run it by folks here for confirmation.

Pushing the 4WD Hi button I hear the transfer case actuator run, but get no sound from the front diff actuator (the ADD, right?). A few seconds after the transfer case actuator stops, the 4Hi button starts blinking. I have not tried to see if it's actually in 4WD or not, I've assumed not. Push the button again, transfer case actuator runs and the light goes out.

Getting under the truck, I did find some exposed / dangling wiring to the ADD:



Front of the truck is to the left. The exposed wires on the left go up into the harness, the wrapped wires on the right go to the actuator connector. Am I right in thinking this white connector isn't factory? Certainly these wires shouldn't be dangling under the diff. Any idea where they should be tucked away?

I think my problem is that the ADD isn't working. Either it's bad or this patched wiring is the issue.

Any ideas on how to confirm the wiring? I can spell multimeter (and I own one), but I'm not terribly well versed in using one. Any help with a step by step in checking this wiring would be helpful.

If the wiring checks out, I think I'll need an ADD actuator. Any tips on good after market brands or the best place to buy an OEM would be appreciated too.

 

Lots of questions here... I’ll try to answer what I can.
first off, you must shift into 4LO in neutral, and if it won’t go into 4HI, just drive forward a few feet. I’m sure you know this already, but I’m just eliminating the obvious.
The wiring appears to be factory, but it should be above the diff and not hanging below. I’m guessing that someone was in there trying to diagnose the problem and gave up.
If you hear the transfer case actuator, then yes, it’s the ADD actuator. 4HI flashing tells you it did not engage. It’s not terrible to remove. I would pull it and take the plastic cover off and see what the condition of the contacts are. You may be dealing with corrosion inside the actuator motor. Be prepared to loose some gear oil when you remove the actuator.
I bought a new one when I did mine. After trying to fix the original, I finally gave up and bought new. I looked for a used one, but a new Toyota unit wasn’t that much more. I bought mine through partsouq.com
It was the cheapest retailer I found.
You should be able to find the wiring diagram on line, so you can test the voltages going into the actuator. More than likely, you’ll need a replacement actuator.

 

Test:

1) With engine ON put truck into ‘D’ and start driving.

2) Whilst driving (rolling wheels) in ‘D’ push ‘4HI’ button and wait for engagement (light clunk/click).

3) You should be in 4HI.

4) Come to stop. Now put truck in ‘N’ in stopped position. In stopped position (you are still in 4HI), push the ‘4LO’ button and you will hear another slightly louder ‘clunk’.

5) You are now in 4LO. To drive in 4LO, now put truck into ‘D’ to move forward.

***You can reverse these steps to get back out of each mode. Wheels need to be rolling to go in and out of 4HI (without blinkings). Wheels need to be stopped and truck engaged in 4HI and in N to engage into 4LO.


Those wires? I have no idea. My truck has the wires up over all axles/diffs etc.

 

OK, so far I've only been testing at rest. I need to get it moving and try again. It'll be pretty funny (and fortunate) if my only problem is driver ignorance. I'll give that a try tomorrow.

This is the first 4WD vehicle I've owned, so no advice is too basic, LOL.

 

Only drive straight when in 4WD. No turns on pavement. Turns bind up the gearing. Turns are ok on soft dirt/sand/snow.

 

The axle disengage is likely not working. Shift it to 2HI go under the truck and try to spin driveshaft by hand. If it spins, the t-case is disconnecting and it’s the axle actuator not disengaging.

 

Snagged this from the FGT FB group

 

He hasn’t performed actual driving and engaging of the 4WD. He has only pushed the buttons in park.

 

Well, today was busier than expected. I did get to drive the truck today and I tried 4hi while moving on my long gravel driveway. Still just a blinking light. I did not get to get under the truck and check anything or determine if it is actually going into 4hi or not.

Probably not going to get into it until next weekend at the earliest. Still would like to know what to look for as far as voltages.

 

So, 3 years later and I finally installed the new actuator when I did my steering rack, and still no 4WD. Hit the 4hi button, same result, blinking light.

The new actuator works, it was delivered in the 4WD activated position so I had to energize it to put it in 2WD mode. For some reason it's not getting power.

Looking at the service manual, there's a relay on the passenger side dash or under-hood in the circuit. I'm thinking either that or the sensor in the transfer case that tells the system that the transfer case is in 4WD are bad. Or I've got a wiring problem. Or, I suppose, maybe it's not fully engaging 4WD at the transfer case even though I hear the actuator running.

 

If you have a voltmeter and a jumper wire you should be able to troubleshoot the relay and wires.

 

I'm having the exact same issue. I replaced the 4WD computer with the hopes that it was the culprit. Nope! I actually couldn't find that replay on the passenger side, this is what it looks like behind the interior panels on the passenger side:


A quick and easy step towards a diagnosis is to turn the 4WD on and see if you can spin the front driveshaft. If so, one of the actuators is working. If you can't spin the front driveshaft, then jack up the front wheels and see if the driveshaft spins when you rotate them. If it does spin, that means the ADD is working but the transfer case actuator is not. If it doesn't spin, that means the transfer case actuator is working but the ADD is not.