4wd actuator not actuating

I have a 2002 with the automatic transmission and push button 4x4, and a few weeks ago, my 4x4 light came on for a minute while driving to work. This was unprompted and nothing happened, so I didn't think anything of it. Two days ago, I got to a trail, pressed the button, and nothing, no blinking or solid light. Could that light randomly coming on have been a code of some kind?
I don't know much about the wiring for these systems, but I assume the light flashes while the transfer case actuator is engaging and solid when the ADD engages, correct me if I'm wrong. My assumption is that because the light is not even blinking there is something wrong at the transfer case actuator, so I took it apart at the campsite and cleaned up those electronic contacts as best I could. There was some corrosion residue in the plastic housing, but didn't look to affect the contacts.
I've been frantically searching forums for this situation, but have yet to come across anything. If anyone has any suggestions on what to do next that would be greatly appreciated. And yes I have checked the fuse.

 

First thing to check is if the transfer case actuator is engaging. Depress the 4wd button and have someone crawl forward slowly in drive while you carefully peak underneath and determine if your front driveshaft is spinning. If its spinning, your problem isn't the transfer case actuator.

Start there and report back

 

When I press the button, the motor doesn't make a sound, and the driveshaft remains free. That's why I think the issue is at or before(?) the electric motor thing. I may just order a new one just to swap the motor onto to test. Lmk if there's a better route to take.
Thanks

 

In that case you may want to check the 4wd button itself. When depressed I believe you should see 12 volts at the connector to the transfer case actuator. If you don't have power to the motor, then your motor may not be the problem. I believe there's a 4wd relay behind the kick panel in the passenger floorboard area. That relay could be bad too.

I'd do more research and diagnostic testing before throwing new parts at it

 

Thanks for the suggestion. After some googling it sounds like the push button system doesn’t have that relay just a 4wd ecu, which I’m praying doesn’t need replacing.

 

Also does anybody know exactly where that control module is? I read it’s on the driver side under dashboard but I cannot locate it

 

The great thing about the actuator is it's literally just two wires. You can jump them to your battery in a pinch. Flip the polarity to lock/unlock

 

Does the rear differential lock run through the control module? I got the diff lock to work in 2 low

 

Typically the diff lock will only engage in 4low, but maybe its only looking for the "low" part of that vs. the "4WD" being engaged.

 

That’s what I’m thinking, but curious if the control module is recognizing low range and doing its job or if the module is a separate entity and could still be broken

 

I have the FSM at home (paper copy). I'll upload some pics of the 4WD system section this evening and see if helps parse this all out.

 

Sweet thank you. I’m bad with electrical stuff so I’m hoping it’s very surface level. Are there replaceable bits within that 4wd module if that is where the problem lies?

 

I didnt know there was a push button 4wd system on first gens. I thought it was a manual 4wd lever

 

The last few years of the first gen got a push button and the actuator system is very similar to later models

 

There was both J-shift transfer cases (manual 4WD lever), and push button 4WD systems (still a button on the side of a 4WD lever that selects high range, neutral and low range - the button only engages 4Hi).

Both options existed throughout 1995.5-2004, but typically you'll see manual transmission trucks with the J-shift, and automatic transmission trucks with the push button transfer case.

 

Thank you for these diagrams. Although I'm not entirely sure how to use this to troubleshoot, I'll break out the multimeter and give it a try. As for the dash light, I see that it is looped into this diagram but I don't really see where in the system. I'm trying to reason why mine doesn't blink at all, when most ADD issues I read about result in a continuous blink.

 

Have you checked the transfer position switch on the transfer case yet? That switch tells the 4WD ecu that the tcase has engaged the front drive shaft, then the signal is sent to the A.D.D. actuator to engage the front diff. Also, the 4WD light won't flash if that transfer position switch isn't working. It should be located somewhere up high on the transfer case, near the actuator.

Let me see if I can dig up the test procedure. It's a real easy test.

 

Hey thanks for the position switch diagram. I finally got around to testing it and I am getting continuity when the switch is depressed. I was hoping it would be that simple but so it goes. I’m going to mess with the wiring at the motor tomorrow and report back.