4wd System Operation & Help Thread

Clear as a Maine north woods cold water spring. All I have to add is: Thanks again, and:

Do not zone-out and shut off your Tacoma when you're in a hurry, AND while the 4WD system is in the middle of/still working on your H4 to H2 shift request. Ever

 

The Internet suggests that this 'body grease' is Molykote YM-102. Had a quick look and it is lithium based, but doesn't seem too easy to get.

 

Thanks again to everyone. My problem ended up being the 4wd switch on the transfer case. Although it bench tested ok, it did not work in place. Replaced it with Echlin part # ns6421.

Unfortunately I had already mistakenly replaced my stock front diff add with a Napa unit that was defective out of the box. It would actually make an audible beeping noise when trying to engage 4wd. I bought and installed the Aisin part #

$183 sat017 AISIN SAT-017 OEM differential lock actuator - compatible with select toyota 4runner, FJ cruiser, tacoma

sat017 from rock auto and all is well. (The aisin part is much nicer than the Napa unit with better fitment.)

My advice is to start with the back probing of the 4wd ecu. It seems overwhelming at first but really isnt that bad and will lead you to your problem component and save you from spending money where it isn’t needed.

 

Quite hard to find, & the price seems extraordinarily high. $50 for a 50 gram container. Meanwhile Molykote YM-103 can be had for $100 for 1 kilogram of the stuff.

I prefer to use OEM spec'ed lubes/greases if possible. If anyone finds a credible substitute (or a fairly-priced bulk source of YM-102) pls post. Thin, clear dielectric grease is better than nothing, but there must be a reason Toyota used this expensive stuff from the factory.

 

After some digging around, looks like there are probably several Molykote substitute types that would work. "Molykote 33 Light Low Temperature Silicone Bearing Grease" is plastic/rubber-compatible & wide temperature range, available for $30 per 150g tube on ebay, shipped. ( $0.20 / gram.) Possibly Molykote Plasti-slip PG54 would work. I just can't see my way to paying $1.00 per gram for Molykote YM-102.

I ordered Molykote 33 & will post pics of the substance itself, along w/ comparison notes to YM-102 (texture / thickness / spreadability etc.) sometime in 2nd half of January '23.

 

okie dokie got a new one for you legends.

bought a used 2010 DCSB

4x4 blinking

previous owner could not tell me the day of the week but was able to get it into 4 lo for me briefly so i assumed not a huge problem

got home and started digging.

started at the ADD. little corroded but nothing crazy. cleaned up soldered and re installed. no dice

went to the t case actuator tried the same thing, pulled the whole unit.

this one was even cleaner than the ADD. and both switches checked out for continuity.

everything is reassembled and nothing has changed. did take me two tries to line the gears back up on the transfer case actuator not too big of a deal for me just set the shaft all the way in and the limit switches to 2H position as there is a stopper there, made sure not to move anything as the drive gear went back in. seems to be all set but maybe im overlooking it.

t case does engage manually. when i put ADD back on i wasnt thinking the system was so particular and just lined the fork up with the wheel, it happend to be to the drivers side of the race, locked in as i understand.

so did some more digging and found this wonderful thread with wonderful group of very smart people.

here are my limit switch readings


2H 4H 4L
TL1 12v 12v 12v
TL2 12V 12v 12v
TL3 0v 0v 0v
4wd .13v .13v .13v
L4 .05V .05V .05V
DL1 0v 0v 0v
DL2 0v 0v 0v
ADD 0v 0v 0v
2-4 0V .68V 12V
LO 12V .68V 0V

Cant make much sense of it hoping someone can shed some light.

also EE ground looks fine, all 4 coming off are in good shape and the crimp and nut still nice and shiny.

will start chasing wires tomorrow, as laid out previously and report back. crazy wealth of knowledge in here hopefully i can add to it. if it is a ground ill trace wire and see where the trouble spot is.

 

Going by the voltages it appears the Transfer Case is in 4low but something is definitely going on at the ADD as they are all at 0v.
Unplug the ADD and verify DL1, DL2, and ADD go to 12v, if they do then you have a problem in the ADD if they don't then the one(s) that don't are likely shorted to ground somewhere.

 

t4 good buddy, but what do you make of 12v across tl1 tl2 and then nothing at three?

 

It suggests the Transfer Case is in 4 low (see the chart), whether or not it is timed correctly is hard to say but we need to fix the known issue on the ADD circuits first.

 

Ok as follows 1-6 on add Pinout in 2H
10.6
10.6
.13
10.6
.13
.13

Bad ground. Thank u nys salt miners. Gonna chase these wires up and see if I can find a crumble. Also gonna dig thru this thread on fuse panel figure out which pins should read what and deduce where the break must be in the line….North or south of my meter. I’m pretty sure it’s in this thread already but if not anyone know what pin out numbers are?

 

Pinout on t case actuator 1-6
9
9
.05
9
.05
.05

connector Pa
Pin #
19 =0v
18=0v
7 = 0v

guess it’s somewhere from connectors on actuators to glove box? This should be good. anyone have a source on those dammed plastic connectors. Gonna murder a few I’m thinking

 

Those voltages are with it unplugged but plugged in they are all 0v?

 

Correct that’s on the connector unplugged and the 0’s came off the ecu behind the glove box with everything plugged in

 

Sounds like the ADD has a problem if DL1, DL2, and ADD are all at 0v with it plugged in but all to 12v with it unplugged.

 

Ok u think it could be the detection switch? I soldered the motor but not that switch. Also I Bench tested the motor and it was good.

 

Something is going on with the limit switches internally, they should not all be at 0v at any time. The 4wd ECU sends out 12v and the switches pull it to ground when they close, they should never all be closed at the same time.

 

Wouldn’t a ground short on one of the three make them all 0v if it was in the correct orientation. Also ran ground check from battery negative to EE and got a bounce around as high as .08 once.

 

If the ground was open they would all be at 12v, if one or more of the limit switch wires was shorted to ground they wouldn't all go to 12v with it unplugged.

 

Got it got it. Ok yup I follow. Well guess I’ll pull it again and run some tests from the inside I suppose it could be the pins on the connector? It did have some crum inside so maybe it’s just corroded too far guess I’ll bite the bullet and order a new one.

 

Hi folks new member here 2006 Tacoma 4wd 6cyl 180k miles. Excellent thread - used it to rule a lot out. 4wh and 4wl lights blinking, no action on tcase actuator at all with switch. Confirmed truck is in 2h (front spins independent and front shaft spins). Can apply power to get tcase engaged and manually engage also. Pin ecu test with key on in 2h switch position mostly checks out except b24 and b13. I feel like likely suspect is b13 showing 12v when ADD clearly not locked. Any advice on confirming DL1 is faulty without pulling front actuator?