2001 Tacoma 4wd / ADD issue

Correct

 

Any idea where that switch is, I was crawling around under the truck and I saw something on the transfer case on the passenger side that had three wires going to it, and then something on the rear transfer case actuator with two wires going to it. Forgive my ignorance, I'm new to wrenching.

 

There should be one somewhere on or near the ADD actuator on the front diff, as well as one (or perhaps more) on the transfer case. They'll look like this one here (which it sounds like you noticed on the rear of your transfer case).



I say perhaps more than one on the transfer case because I feel like I remember reading there were 2-3 of them on the transfer case.

Here's the testing procedure to determine if the switch is still good or not (credit to @Strictlytoyz for the graphic from another past thread).

 

It should be on top of the tcase actuator. It's a 2 wire switch that tends to get stuck when not used for a while. It's a simple ball and spring design.

 

OP, are you able get the truck up on jack stands and verify wether or not the transfer case is engaging the front driveshaft when you put it into 4hi? This will tell us if it's an A.D.D issue or tcase issue.

 

You can actually just drive it forward and backwards after pressing your 4WD selector in and have a friend watch for the front driveshaft to spin (without getting run over of course), to determine if the transfer case is indeed engaging or not.

 

It is definetly an ADD issue from what I understand. I had the truck jacked up the other day and the front driveshaft was engaging, no light on dash though. I'll try out the 4wd position switch tomorrow.

 

Okay, yeah if the front drive shaft turns sounds like the 4wd switch is the next culprit in line. You can either jumper it while in 4wd and see if it wakes up the A.D.D. or ohm it out like @Red_03Taco posted above. Whatever you prefer.

 

Lets just say hypothetically I test this and it is the issue, Any idea where I could get that switch? It seems like a generic switch but when I type it in I'm not finding anything.

Still plan on testing this today when I get some free time.

 

Part # 84210-04010

It's labeled as a back up lamp switch but it will still work. The switches are all the same, just get the least expensive one.

 

No continuity when the switch is unpressed and no continuity when it is pressed either. I suspect I've got my culprit but I'm going to remain cautiously optimistic. Should have a new switch by tomorrow. I suppose if I have someone press the 4wd button in the truck while I use a jumper on the connector underneath I could verify it tonight. Thanks for everyone's help thus far!

 

Is this the switch on the ADD actuator or on the Tcase?

 

This is the switch on the tcase actuator, same one circled in red in your picture above.

 

You could remove the switch and probably lube it up and get the ball and spring in working order again, it might be frozen. Jumping the pins on the switch should in theory send power to the front A.D.D. actuator while the 4wd button is pressed. I believe if you also jumper it while in 2wd you should get blinky 4wd dash indication cause it'll think its in 4wd.

 

Yea I think you've likely found your culprit. If there's no signal from that switch then the 4wd ECU won't send power to your ADD actuator to engage the front diff. I would do what @Strictlytoyz said to confirm this is the case

 

Good news, the switch was the culprit! I'm glad to have consistently working 4wd when I need it (knock on wood). Any chance you guys know what size o-ring goes on the rear t-case actuator? The one on mine tore when I cracked it open the first time and I forgot to keep it to measure.

Also, Thank you guys for all your help!

 

Congratulations on the fix! Nice that it was something pretty simple.

Sorry I don't know the size of the O-ring for the rear Tcase actuator (might consider just carefully running a bead of FIPG around it for now). But here's the part number for the O-ring: 96711-19025, and it shows in stock for $2.76 at ToyotaPartsDeal.

 

Good job OP

 

Reviving this older thread because I’m currently chasing the same issue. It’s either the 4hi limit switch, or a bad Dorman front actuator.

New dorman ADD (4mo old), opened it up its perfect and motor connections were soldered from factory. Now that its -20c, I get the flashing 4x4 light and the system is locked there, no clicking. This time, by the time it warmed up in the garage it worked again with no troubleshooting. Cabling and connectors are perfect, tubing perfect, and rear tcase actuator opened and regreased, it looked new inside.

Limit switch on tcase did work well when bench tested, but had a bit of a big dead zone when testing continuity compared to the 4hi LS.

My question- Are the dorman ADD’s known to be flakey compared to the Aisin? Should I suspect it could be intermittent after 4mo and maybe two dozen 4x4 activates?