4WD Not Working...

Best way to test it? Right now I have absolutely nothin happening with my 4WD. No noises, lights, movement. But I have tested each actuator with a separate power source and they both work. I also only see two position sensors but the drawing shows 4 I think.

 

Have you searched?
This thread has Alot of info:
https://www.tacomaworld.com/threads/transfer-case-transfer-cases-in-first-and-2nd-gen-trucks.345652/

The actuator's need feed from the sensors to achieve voltage by way of the 4wd ecu.

With an automatic transmission you should have three sensors on the transfer case. A manual equipped truck has two.

Unfortunately. The most reliable source, the Fsm, is inaccurate in the TC actuator connector testing procedure.
The rear actuator has the same connector as the front actuator. The rear has five wires, and I believe the front has six.

But I'll link it anyway, it may be of use.

 

Yea man I've been searching on this topic for many many weeks trying to figure it out. I found a copy if the family you linked too, but like you said the connectors on my truck don't match the book so that's been throwing me off. Also I've read some places where they say my truck didn't have a separate 4wd ecu, obviously I know now that it does. A few other things that I've come across that haven't been factual. Lots if misinformation out there. I appreciate your help though. I've got one postion switch left to find. I've only found 2 I think. Then start testing the ecu. I'll report back this weekend.

 

Please report back. Alot of people have had this issue and disappear without describing a resolution. I've read of at least one person throw most parts of this system at the problem ($$$$) and it didn't even fix it.
I'd be inclined to say that whole ADD 2-4 actuatored system is the only mystery left in these trucks.

 

So I just relooked at the links I posted. The testing procedure in the fsm may be correct. The picture of the connector may be wrong. But the number of pins in the 2-4 diagnoses lists five pins, which is the amount of wires on the TC connector. Maybe you can look at the wire colors & pin numbers in the EWD and see if you can diagnose it and figure it out. Here's the correct TC actuator connector:


PIN1---- Light Blue

PIN2----White

PIN3---Yellow/Red line

PIN4---White/Black line

PIN5---No wire

PIN6---Pink

Also it wouldn't surprise me if the 2nd gens and possible 3rd gens use the exact same system. And there may be far more info in other sections then just the 1st gen forum.

Edit: This is interesting. Not that it applies to your problem. But there's some interesting info in it: https://www.tacomaworld.com/threads/4wd-actuator-problems-feedback.559051/

 

That is the correct connector for me. I picked up an extra shift with my EMS job so I’m gonna try to get to this tomorrow

 

Alright, I gave it a shot but all the wiring diagrams I could find and plug connectors, 4wd ecu pinouts, nothing matched my truck. So I just took it to a local mechanic to figure it out. I'll report back once I hear from him.

 

JaceF8, any news from your mechanic on this issue?

I'm having a similar issue and this thread has some good information for troubleshooting, just curious where this ended up...

 

Any news???? I would love to know what happened. I am in a similar situation now. Dammed ADD

 

this is for a MY 2003. 4WD starts plate 20 ish depending on motor/trans.

 

Sorry for reviving this thread… but I exhausted all my options and I’ll admit- I NEED HELP.

2004 tacoma 4wd, crawl box, everything done to it.

4wd hasn’t worked for a while. I have it up on stands right now. 4wd light on dash is blinking. I took actuator off of transfer case. Reset it, put it back in, and light was off. Then pushed 4wd button, I can hear it engage. Still blinking. I have the ADD actuator off now, and tested it with a spare battery and it moves the fork left and right just fine. When I go to plug it back in, it does nothing. When I try to Unclick the 4wd button it does nothing. I can only manually disengage it.
On the 1st gens I saw that the tubeon the actuators is not a vacuum line. Is that correct?

both actuators have been tested and I got both to work by connecting leads to different plug terminals.
One thing left to test tomorrow… I checked the 20 amp fuse, it is good, I just gotta check the voltage at the fuse.

 

Is there anything I can check at the 4wd ECU? I found it in the dash below the stereo deck

 

The actuators need feedback from the ecu, 4wd ecu(push button) & up to three TC sensors. Have you continuity tested the TC sensors? Continuity tested the connector? Inspected the wiring? If yes, then throw parts at it.
Hate to recommend that.

 

I actually did not test the transfer case sensors. I have not seen a write up on it. How would I test those sensors? Pretty sure my truck only has 1. Pretty sure there should be a second one somewhere I’ll look tomorrow

 

You'll see them on the TC, 24 or 27mm bolt head. Near the top, two wires, gray connector. They're normally open switches, so when they're activated it closes the switch. Up to three according to my ewd.

 

so this is what I found- one sensor near the 6 prong connector, and 2 wires leading to the top of the T-case. I guess I’ll start testing to see when/if they get power in different modes

 

I am getting almost 9v out of this plug

 

Tested it. No continuity when No depressed. Good continuity once it is compressed

 

At the fuse I’m Getting 12.5 v

 

Download the 2003 fsm manual( good for 2004 ) that's been listed on here. It's probably your best option. Good luck.