A couple of weeks ago, after 8 inches of sleet/snow/ice fell, I needed to engage the rear locker on the 99 to back out of the driveway. The front locker too, FWIW. The locker engaged normally, everything worked until I go to the street. Tried to unlock it, no change at all. Locked light remained on. I tried locking/unlocking several times, no change at all. Had to go to work, so I just drove in with it locked.

A couple of days later the temps improved slightly, to maybe 20 or so, so I did some basic multimeter testing at the locker ECU plug. Everything seemed fairly reasonable given that the locker was engaged, and I have the 'gray wire' mod *locker ECU always thinks it's in 4LO). Dash switch is working, both fuses that are involved (4WD and GAUGE) were good. It just didn't do anything when the button was put in either position. Pulled up the carpet under the left rear seat and checked there, again, everything seemed reasonable for the locker being locked.

So I manually jumpered 12V/GND to the M1 and M2 terminals there, and the locker engaged and disengaged normally. Curious. I left it unlocked, plugged everything in, and tried the dash switch. It locked again, but sounded weak? Wouldn't even attempt to unlock. I manually unlocked it a second time, and tried that again. This time it sounded even weaker and didn't fully lock, just sort of stopped in between locked and unlocked.

So I started jumping to conclusions. We replaced the harness between the body and axle/actuator only 2 years ago. So I assumed that was OK, because it was locking and unlocking normally jumpering it at the rear seat. The actuator was good, because it was locking and unlocking normally. So I decided the locker ECU was bad, and ordered one on eBay for $26 shipped. After 4 or 5 days, it came in. I took mine out and took out the board and looked at it carefully, expecting to see some bad solder joints. Fairly common on decades old electronics. But everything looked great on it. Plugged the new locker ECU in and..... no change at all. Exact same situation. It would weakly lock when manually jumpered, then wouldn't do anything else until manually unlocked again.

At this point I jumped to another conclusion. Despite being wrong and firing the parts cannon prematurely on the locker ECU, now I surmised that the actuator itself was bad. The limit switches inside the actuator motor didn't seem to be working correctly. So I ordered a new actuator. Yeah, I should know better, but I thought I'd narrowed it down. Not the ecu (both work the same). Not the harness (it's only 22 months old!). Must be the actuator?

Anyhow, that came in yesterday. And finally, the driveway isn't full of melting slush and ice, so it's a little nicer to crawl around underneath (it doesn't fit in the garage where it's dry, even if I kicked one of the garage queens in there out into the cold). Wen t underneath, unbolted the harness support bracket on the actuator, unplugged both harness plugs (which is a blind/awkward PITA), intending to plug the new actuator in and try it a few times before replacing it. But surprise, the harness was damaged near the actuator plug. Most of the wires had damaged insulation, a couple were completely severed. One was severed in 2 places, with 1/4" missing. The M1/M2 wires, though damaged, were still mostly connected. Well... I think I finally belatedly found the real issue. The unlock limit switch wire was broken, so the ECU wouldn't try to unlock it because it assumed it was already unlocked. The dash switch that lights up is run from an entirely different switch on the fork, the ECU doesn't see that, only the internal lock and unlock limit switches.

No clue what damaged the wires. It looks pinched, certainly doesn't look like rodent damage. There's nothing around above the axle that could have hit it, just the parking brake cable, and that moves up and down with the axle. I've seen cold temps crack wiring insulation, which then flexes and breaks the metal strands when flexed (like in door jams), but these looked crunched/snipped, not frayed. Really not sure, best guess would be a rock got clipped up on top of the diff, bounced around a little, then went on its way.

Anyhow, ordered another locker harness (the cut/damage is really close to the plug, hard to butt splice). Feeling a bit dumb for firing the parts cannon with wild abandon before firmly arriving at a diagnosis. In my (faint) defense, it was nasty weather and lousy conditions to be crawling around under the car, and it was a quirky failure where it sort of worked. Plus assuming the harness I'd just replaced was still good.

 

Good job. As the kids say "pics or it didn't happen". would be interesting to see how mangled it is.

 

Here's a pic:

 

Plugged the new harness in, and everything is working normally again.

Lousy diagnostication on my part. But there were some confusing aspects. The weak engagement from the dash switch, vs. unlocking and locking when jumpered from the rear seat and a spare battery. I didn't really considered a partially severed wire that would 'sort of' actuate the actuator. And I missed the main failure that I could have detected - the lack of an unlock signal. I could have tested that while manually locking and unlocking the actuator at the rear seat connector.

In retrospect the manual locking/unlocking (jumpering from the rear seat area) was also a bit weak, I just didn't notice it because I was mostly seeing it actually locking and unlocking, and I don't normally hear how quickly this process takes.

All's well that ends well.

 

Don’t feel bad, I once spent 4 hours troubleshooting my STI’s windshield wipers not working only to find out I brain farted so hard that I was twisting the rear wiper and forgot moving the stalk up and down was for the front wipers……

Glad you got it sorted

 

We all have those moments, don't we?
He is still having an issue, looks like the e-locker is not entirely behaving the way it's supposed to. We can hear the actuator move back and forth, but the actual locking part isn't happening.
I'm alllmost curious enough to pull the 99's e-locker today while he's working since it's a snow day for me...but for the, you know, snow.

(brain farted so hard... )

 

Yeah, it sounded so healthy cycling back and forth with the wheels on the ground that I yet again jumped to a conclusion it was working, didn't test it. The next morning, driving to work, I tried engaging it in a parking lot. Not engaging. It just stays flashing as I turn in S curves back and forth. Doesn't seem like it's cycling long enough to actually engage it.

*SIGH*

 

OK, after removing the actuator (which was still audibly moving when locked and unlocked), and then testing them off the vehicle, I think the conclusion is that manually jumpering the M1/M2 motor wires to reposition the actuator is very risky. The actuator limit switches normally limit the movement to a much smaller range. Manually jumpering it can move it outside this range until it hits mechanical limits - there are some cast raised areas inside the gear housing of the actuator itself. But at that point, I think it's possible to be outside of the expected positions, so when the locker ECU runs, it sees a limit switch change state and stops trying, well before it's in position. And before figuring this out, testing it on the bench (err, kitchen table) revealed that it can power through the mechanical limits, the (well used) locker from my diff was continuing to turn, with the gear hopping up and down some as it pushed past the mechanical stops.

Took it apart, discovered what it had been doing, repositioned it, and now knowing how sensitive it can be to 'over positioning', I tested it by manually jumpering it again, and it worked.

And it turns less than I thought it would as well. The mechanical limits are just under 1/2 turn. And the 'logical' limits, as defined by the limit switches, are only about 1/3 of a turn.

Fun fact - I tried manually repositioning the brand new actuator (before finding out that they're sensitive to hitting the mechanical limits) and it just plain stuck. Didn't keep going like my worn one did, it just sort of jammed and couldn't be backed (by jumpering the opposite voltage to M1/M2). I had to take it apart and manually reset the position.

So to sort of sum up -
1) Initial problem - the wiring harness was damaged at some point, possibly by some sort of trail or road debris, breaking the unlock limit switch wire. Preventing the OEM locker ECU from attempting to unlock, because it was seeing an unlocked signal already.
2) Second problem - while testing out the issue, I manually jumpered the rear locker back and forth, and left it unlocked so I could drive it. This was probably at a mechanical limit, possibly slightly beyond (being installed, it probably was limited by the locker fork from moving too far). But it was probably too far for the limit switches to make sense to the locker ECU
3) Relaced the harness, and tested it via the dash switch. And it actuated and moved, as expected. But my theory is that due to it being so far out of position, it was only moving a tiny fraction of what it should. From over-unlocked to properly unlocked.
4) Manually repositioned it, cycled it a few times uninstalled (so it positions per the limit switches, only turns 1/3rd of a turn), back in business.

Installed it all back int he diff, and it's locking and unlocking properly again, verified with a wheel off the ground.

So yeah, be aware that jumpering it and moving the actuator that way is very risky and can leave it in an inoperable state that requires removal and partial disassembly to reset and reposition.

 

96 4Runner 334,475 miles

I had a small package coming so when UPS showed up I went out to get it and save the guy some walking.
The only problem was he kept getting stuff out of the truck !!
(???)
Too much stuff! Too much stuff!

Turns out when your husband asks you what you want for your birthday and you have no clue he might say something about getting you some wagon wheels
which immediately makes you think of actual Conestoga wagons and you know that's not right and that he's messing with you

but then...

Ohhhh....


A much nicer refurbished set of two tone land cruiser 16x8s (camera didn't pick up the subtly different greys) to wear my next set of tires when the current BFGs are done.
Was not expecting that!

And, as said husband reported, we, mostly he- (I was there for moral support and to be cold)- worked out the e-locker problem on the 99. Turned out getting the Aisin was not a waste, the 99's locker has difficulties.

I do have another spare junkyard locker I pulled some time ago that he could have used, am glad to still have it for Justin Cases.
I plan to pull the 99's former locker all the way apart to see what's what, you know how I love to do that sort of thing.
If it's salvageable we will, if it's not we'll hang onto it for parts.

 

Yeah, the actuator off the 99 was sounding a little noisier than the new one or the spare one. Just a little more rattly and geary sounding? Still working, still actuating properly (once repositioned), but I put the new one on.

And yeah, the 96 needed some nicer shoes!

 

96 4Runner 334,475 miles

New Red Top start battery. Finally got around to swapping the weak 9/15 Optima battery.
It did rally and was doing most of the starting on its own, but it's going to be super cold next week so it was time.
Having an Optima dual battery box limits what I can put in there, but I've got no problem with how long the red top lasted.

I stayed with the redtop over a yellowtop for the start battery because it's lighter than the yellow and is the one that hangs off the inner fender.
The new Optimas are still made in Mexico, but are now a Clarios brand. There's no date sticker or date of manufacture that I can find anywhere on the new battery, that's disappointing.
If I need it warrantied they'll use the sell date on the receipt (1/7/25 in my case) for the age. I registered it easy enough on the optimabatteries.com website and will tuck the receipt away somewhere 'safe'.

 

96 4Runner 334,xxx miles

Nothing too exciting. My left low beam headlight burned out a bit ago, a few days later the right one followed. I had to use my high beams to get to work for a couple of days, luckily this past week was spring break.
Interestingly (to me), I have not once been flashed for my high beams including the stint of very dark section of road that leads to my job. That's got me thinking about how not-bright they actually are.
The bulbs were last replaced in 2018, that's prolly part of it.
More on that later this week.

I spent this week removing the left headlight and marker light because with the dual battery box and ACR that's the only way to change the bulb. 2 screws, 2 bolts, 2 nuts, what would normally be 2 plugs but are 3 for the bulbs. The hardest part is removing the marker light post from the headlight assembly, it's a straight forward from the truck pull, I can see why the plastic arm where the post fits into the headlight assembly often breaks.
Some re-repair was done to the grille where the upper supports were cracked and glued back together and have separated again.
I realized my high-beam indicator is not working, then noticed the ABS bulb was also out. Replaced those bulbs.

 

96 4Runner 334,xxx miles

I was chatting via email with Daniel Stern about headlight bulbs for the 99 in December. He said that while the bulbs were going to be better than what was in there the best change I could make for brighter headlights was to replace the reflectors.
The 99 got bulbs but I didn't forget what Daniel'd written.

Fast forward to the 96's nearly 8 year old low beams going out and having to use the brights, but nobody noticing the brights were on while on my dark drive to work.
Huh.
Then a week or so ago Serra Toyota has to go and send me a very nice extra discount...

It was a difficult decision to spend money on something I already have that I thought were pretty okay, but after a lot of debate I went for it.

For fun, the 96's original headlight- it's been years since these were changed for a set off a newer junkyard truck

The newer style headlights from said junkyard truck that've been on the 96 a very long time- this is the best of the two

The new headlight-





Okay, this is not the worst update ever.


The headlights come bare so I'll move both backs to the new glass. I'm also upgrading the wiring harness while I'm in there.
More to come.

 

Nothing like some nice shiny clear new headlights!!! Congrats

 

I didn't realize how fuzzy my reflectors were, agreed!

It wasn't hard to move the headlight backs to the new headlights. A spring, a post, 2 adjusters. The post moves most easily at the backing side where there are 2 small catches. I marked the adjusters, unscrewed them enough to access the headlight side where there are more small catches to release them (empty squares in pic). One of the adjusters was too rust-frozen to use, but I had a spare.






The dual battery box is making things a bit tight, but the ceramic plug on the new harness fits. Barely. I did wrap it in electrical tape after massaging the wires to make a hard turn, give it a little protection for any rubs. The rest of the harness isn't a problem, there's enough room between the headlight assembly to run it through from where the relays are going to be installed on the front support by the evaporator.


Now It. Keeps. Raining.
Got a chance to pull the 99 up to the garage door, then used sidewalk chalk to mark its position in the driveway and to mark the position of the low and high beams on the garage door.
I used those references to aim the 96's headlights, so that's done.
Working on aiming the low here, high is up and to the left...

 

96 4Runner 334,xxx miles

It's still raining so I did an inside thing today. The Nalgene bottle I'd modded for my washer reservoir in 2018 got brittle over time and cracked so it needs replacement. I was spending too much time on the interwebs this morning when I came across a video from PhoRunner that inspired a trip to O'Reilly's this morning where I bought an MCR-3 A/CPro Coolant Return system for a little over $9.

I did the same thing I'd done to the nalgene, drilled a couple of approx 3/4" holes to barely fit the bushings for the Toyota washer pumps, used some rtv to help seal any juice from escaping. If it does leak I'll have to get new bushings, almost 30 years old and one with a hole...we'll see. Toyota 90099-32089 is the bushing part number.
I staggered the pumps to make room for the washer lines. The direction they faced needed to be considered.


The bottle comes with a bracket I'll modify to bolt to the truck. It's upside down drying now.


There are nipples for other lines on the bottle, but they are sealed so not a problem.

 

96 4Runner

The new washer reservoir is sitting in front of the air box where the old one was. It's a little wider front to back, but also not as tall as the nalgene was so the pumps fit better. I still have access to the headlight too. I cut the bracket that the reservoir came with to fit and zip-tied it to the front support where there was a convenient hole. I put water in to make sure the old bushings I didn't replace can do the job before putting actual washer juice in.


Also the new headlights are in. Looking outwards they're much brighter than the old ones with more light further out, and there's no blobs of light when you look directly at them (low beam). I don't have the equipment to gauge the actual lumens, all I've got is pleased with the results.
I'll have to do a comparison of the 99 with its better bulbs but older reflectors vs the 96's pretty good bulbs and new reflectors.



I wanted to stick to halogen bulbs and came across this thread for a newer Tacoma with lots of good information, thank you crashnburn80:
ultimate headlight upgrade h4 not led or hid

Of the 3 things I did,
the reflector-Headlamp Unit Assembly Left Hand #81170-35300 and Headlamp Unit Assembly Right Hand #81130-35320 (re-use the backings)
and the bulbs 9003 H4 HB2: Osram Night Breaker 220 (would have loved to score the discontinued Osrams in the tacoma thread, am now set up for something like that in the future)
were the most important part of the equation.
The Headlight Services 1995-2002 Toyota 4Runner Premium-Plus Headlamp Wiring Harness, Ground-Switched- is very well made. It has larger gauge wires going straight to the start battery (fused with relays and ceramic plugs) with one of the original headlight connectors as the trigger.
There's enough room between the headlights and the support that I was able to mount the harness to the front support on the left side next to the condenser using the small holes that were already there and run the wires through the holes for the both the headlights and the battery.


I am justifying the cost of all this as being negated by my having no intention of adding a light bar (and that potential cost) to the truck so having better headlights is important.

 

99 with Daniel Stern +250 bulb on the left, 96 with the Osram +220 on the right. The Daniel Stern bulbs are a nicer color temp, a little warmer.
The 99s headlights are in pretty good shape with not too much fuzz, the 96s are more crisp with the newer reflector though not quite as bright. Close though.
Both have good cut-offs.

 

96 4Runner 334,738 miles

Still chasing the P0171. Haven't found any vacuum line issues, maf is clean,
have been noticing the idle being randomly higher than it ought to be when warm. A quick tap on the gas and it settles back down. This has been happening more and more often.

Today I pulled the throttle body to see that there's a bit more play in the butterfly shaft than there should be, allowing the butterfly to be far enough over to keep it from fully closing. I'd decided to do the washer mod to better center the butterfly and keep it from migrating too far over.
Looking for something else I found another TB on my parts shelf that looked good with little play and a well-centered butterfly so changed plans to using that one instead.

It was plenty dirty so I figured the IAC could use a little love


luckily I was already planning on cleaning the other IAC sometime this spring so I already had a gasket on hand.
the air control gadget (right side 'eye'- that shiny thing is static, the other part you can't really see is right next to it) was gummed up, now it moves freely.


And I removed the accelerator controls from the butterfly


And preemptively added a very thin and a sort-of thin washer (top of the stack in the pic).


After making sure all the spring ends were in the appropriate places as well as the stops I carefully tightened the nut that holds all that on. Pretty sure that'd be an in-lb thing, did not want to strip the threads.

Ran the truck until it warmed up, there was none of the notorious high idle that sometimes has been reported after an IAC cleaning.
Now I've just gotta drive it and see how it goes. Next area of attack will be checking the exhaust for loose bolts or leaks ahead of the cat.

 

The 99- 262,355 miles- got a new heater control valve today. The old original (!!) one was turning brownish and though it wasn't leaking (yet) it seemed like a good plan to go ahead and replace it.

All it took to make a good plan turn into a spectacular one was Jomoka beginning the job by simply loosening the hose clamps, both pipes crumbled like so:


He was able to fish the broken bits out of the hoses. There was also some sort of white plasticky bit inside the control valve that had worked itself most of the way loose.