4wd System Operation & Help Thread

The only other connector is EC1, I believe it's above the front axle toward the right side.

 

How did I miss that ec1 on the diagram? It’s a short stretch that connects the wires from the ADD actuator to the harness. The wires on the back of ec1 are toast - bare and green corrosion. I’ll hunt for the ADD to ec1 stretch (it’s maybe a foot long in total) and just replace it. Considering the issue solved. Dm93 you’re a legend. My hat is off to you.

 

Glad you found it, you may be able to find that sub harness in a salvage yard. Worst case you could just delete that connector and solder the wires together.

 

Okey doke, this Molykote 33 arrived. It is definitely a "light grease." Consistency is very close to say, cosmetic "cold cream" like Pond's™. Compared to Molykote YM-102 (aka "Toyota Body Grease," which has the consistency of hard butter at room temp,) this grease is probably too light for many applications. But inside the electric 4WD actuators (transfer/front diff/rear e-locker) I think it might be acceptable. Certainly the temp. range is adequate, and it is spec'ed as "resistant to water washout" as well as "oxidation."

Interestingly, for a grease, it has absolutely zero detectable odor. Not even a trace of odor upon close & multiple sniffs. " Even stuff like Vaseline, olive oil, vegetable oil, etc. usually has some trace of characteristic odor, but there's nothing here to smell in MolyKote 33 "Light." Incidentally, the box says "this product is not hazardous."

I tried smearing a thick dab on a heated stainless sauce pan -- hot enough to cause water droplets to sizzle, so >212ºF; I don't have a temp gun. No sign of melting or breakdown. It's listed as rated for -100 to 400ºF. There's no chance it would break down or liquefy inside any of the electric 4WD actuators under any operating conditions.

Photos attached. I think I might try ordering some other Molykote greases in the same general class but somewhat heavier in body. Must find a substitute that doesn't have the ridiculous price gouging & low availability of "genuine Toyota body grease."
-----

Edit: I just realized that "Molykote 33" comes in a "Medium" weight, as well as this "Light" style. Not sure if it also comes in a "Heavy" weight.

 

Figured I’d reach out to y’all on one more related. Update on 4h is great - driving tests all successful and goes in and out like butter. Performs great. 4L less successful. No light, buzzer, nothing.

After pin testing, I’m getting 9v on the speed sensor with the vehicle stationary (SPD/A9). I’m assuming that’s why it’s not even trying (although seems I would be getting some beeping?). Any initial thoughts or advice on resistance testing the selector switch? Could it be related to the switch, meaning does the speed sensor route through the switch?

checking continuity in each switch position on the three wires in the back there is no change in continuity combinations between 4h and 4L which is suspect to me.

 

No, to test the switch.
Turn it to 4L and then check voltage on pin A15 of the 4WD ECU.
You should read about 0v

If it stays at 12v. The switch or wiring is bad.

 

Also, did you check all the wiring?

 

If it doesn't even beep or flash the low light I'd be suspecting the switch.

Check the voltages on the 2 switch terminals at the 4wd ECU (2-4 (A8 Grey) and LO (A15 Blue)) and see if they match.

The SPD signal is a PWM signal when the truck is moving, it will be at a steady voltage (5-12v or 0v) when the vehicle is stopped.

This is what the speed signal looks like 0-5-0 mph, if your not getting a P0500 code in the PCM there is almost certainly nothing wrong on that circuit.

 

Thanks TnShooter. I did back pin all. It checks out except several in 4L, but the ones that don’t check are the limits AFTER a shift. In this case it’s not even trying to shift. I think you are onto something with A15. I checked A8 also. 4L selector does nothing to either. Here is each pin voltage in each selector mode (2h > 4h > 4L):


A8: 0 > 0.675v > 0.675v
A15: 12v > 0v > 0v

this makes me think the switch is not sending the 4L signal at all. Do you agree?

Dm93 - this also seems to match with what you are saying also.

 

Did you check it with the switch in 4L?
The 2-4 circuit should be 12v in low and the LO circuit should be 0v.

 

Sorry the post above was a typo - I tested in each position (2h > 4h > 4L):


A8: 0 > 0.675v > 0.675v
A15: 12v > 0v > 0v

no change with either between 4h > 4L. I THINK this is enough to justify a new switch cost. Agree?

 

In that case yea looks like a bad switch, verify the voltages are the same at the switch. If they are then the switch is bad.

 

so I’ve got my add back off and am trying to diagnose it on the bench. I can run 12v directly to the connections on the motor and run it but when I wire it to the contacts on the add side it does not spin. Also I do not have continuity between the ground and and dl1 or dl2 inside the case. I guess this means this thing is pretty much junked as there no way to break it down more or am I looking past something? I don’t need to be plugged in to test continuity correct?

 

You won’t have continuity between those unless the wipers on the big gear are in the correct position. The add needs be together to test this. Or the big gear with wipers need to set in place in the correct spot if testing off the truck.

 

Ok with it back together then it looks like a do have continuity but I’m not sure which pin corresponds with what inside the ADD. I was not able to find an explanation of this in the thread

 

Got it thank u sir guess I overlooked that. So I have continuity between 6-5 and 6-4 sitting on the bench but not between six and anything else so I guess that means this thing is unlocked and electric is moving proper ???

 

Well I guess I fixed the add problem. I now have no flashing lights in 2wd and the front is unlocked. But now I cannot get it into 4wd. It seems like The transfer case does not want to shift…gonna try and hot wire it I guess or pull the motor and inspect brushes again

 

It’s would be much easier if you tested at the 4WD ECU. It’s much easier to diagnose this way.

 

I did run test and it all checked out. System thinks it’s in 2H. Just won’t change from there for some reason I guess