rear diff locker will not engage (2 Viewers)

[RockDriver]

Well, an update from me. I got a bit frustrated with the situation, so I booked a diagnostics of this problem with the local Toyota dealer. This is what they found:

• The actuator (motor?) is dead and needs replacing.
• The actuator cable is damaged and needs repairing/replacing.
• The ECU itself is gone, apparently taken out by the previous owner.

So bad news is that there are actually 3 problems - essentially just about anything that could be broken is broken. But the most bizarre one is the absence of the ECU - why would anyone just remove it even if it was broken? Anyway, that totally explains why I wasn't even getting flashing diff lock indicator on the dash.

Repairing at the said dealer would cost a 4 figure amount, so naturally I opted out.

A couple of questions if anyone knows the answers:

Is the ECU (89533-60090) only responsible for the rear diff lock or also something else? Picture below:

How big of a job is to repair/replace the cable that goes from the actuator to the ECU?

Is the actuator itself repairable, motor replaceable? The dealer said they only replace entire actuator and it would cost a fortune (duh). Even used actuators are expensive.

Replacing actuator - does that mean the diff oil will have to be drained and replaced as well?

I could really use the part number, picture, anything related to that actuator cable/harness that goes all the way into the ECU behind the glove box.

 

[porschenut]

Well, an update from me. I got a bit frustrated with the situation, so I booked a diagnostics of this problem with the local Toyota dealer. This is what they found:

• The actuator (motor?) is dead and needs replacing.
• The actuator cable is damaged and needs repairing/replacing.
• The ECU itself is gone, apparently taken out by the previous owner.

So bad news is that there are actually 3 problems - essentially just about anything that could be broken is broken. But the most bizarre one is the absence of the ECU - why would anyone just remove it even if it was broken? Anyway, that totally explains why I wasn't even getting flashing diff lock indicator on the dash.

Repairing at the said dealer would cost a 4 figure amount, so naturally I opted out.

A couple of questions if anyone knows the answers:

Is the ECU (89533-60090) only responsible for the rear diff lock or also something else? Picture below:

View attachment 3837051

How big of a job is to repair/replace the cable that goes from the actuator to the ECU?

Is the actuator itself repairable, motor replaceable? The dealer said they only replace entire actuator and it would cost a fortune (duh). Even used actuators are expensive.

Replacing actuator - does that mean the diff oil will have to be drained and replaced as well?

I could really use the part number, picture, anything related to that actuator cable/harness that goes all the way into the ECU behind the glove box.

I read somewhere that the ECU controls both the centre diff actuator as well as the rear. Not certain at all about the centre actuator though. Caveat...I'm a total electrical newb so I can't be trusted. I pulled my 89533-60090 yesterday to track down my rear diff flashing light. It has a 10 pin connector and 5 wires travel to the rear diff (I confirmed by checking their continuity).

Those rear diff wires travel along the side of the interior along the door sill area. At some point somewhere near the cargo area I believe those wires pass down through a body plug but it's hard to tell where. From below, the diff wires go up from the axle and then above the frame where I couldn't see easily.

As for a new rear diff actuator, they are rebuildable with some elbow grease and gasket maker. Many Youtube vids showing the process for 3rd gen 4Runners, not so many for Land Cruisers but assume but from what I've seen, the process is pretty much the same. That being said, it looks like a re-build would take awhile and so I took a chance and bought this aftermarket one from Aliexpress: https://www.aliexpress.com/item/100...o.order_list.order_list_main.5.174f1802lkyBnD It was about 20-25% of what I could get an OEM for on eBay and it looks pretty good. I bench tested it with the 12V off my battery and it works. Unfortunately for me, it turns out that I have no power getting to the actuator itself so I probably bought it unnecessarily. With good continuity for all 5 wires from the ECU it seems that I've likely got an issue with the ECU (squeaky clean - no corrosion) or (duh) a possible fuse issue which I hadn't thought of until last night. There does seem to be a 20A diff fuse in the passenger side panel for "diff".

The Actuator ECU is actually super, super easy to get to. Just pull off the triangular passenger footwell interior panel first of course. A black plastic cap towards the front just yanks right off and then you pull the panel directly towards the back of the truck. Then you flip upside down in the foot well and will see 89533-60090 hiding in a void behind a beige coloured bracket (holding up a lot of wiring and other modules). The ECU location is right against the firewall and will pop right out of the metal bracket see in your example photo.

 

[porschenut]

FYI a correction to my last post. I found the 20A diff fuse in my driver’s footwell panel. Not in the passenger side as mentioned above. My fuse still worked so it’s still appearing that my diff ECU could be the problem. That or maybe something related to a transfer case sensor (another thread I found here indicated that possibility).

 

[RockDriver]

I read somewhere that the ECU controls both the centre diff actuator as well as the rear. Not certain at all about the centre actuator though. Caveat...I'm a total electrical newb so I can't be trusted. I pulled my 89533-60090 yesterday to track down my rear diff flashing light. It has a 10 pin connector and 5 wires travel to the rear diff (I confirmed by checking their continuity).

Those rear diff wires travel along the side of the interior along the door sill area. At some point somewhere near the cargo area I believe those wires pass down through a body plug but it's hard to tell where. From below, the diff wires go up from the axle and then above the frame where I couldn't see easily.

As for a new rear diff actuator, they are rebuildable with some elbow grease and gasket maker. Many Youtube vids showing the process for 3rd gen 4Runners, not so many for Land Cruisers but assume but from what I've seen, the process is pretty much the same. That being said, it looks like a re-build would take awhile and so I took a chance and bought this aftermarket one from Aliexpress: https://www.aliexpress.com/item/100...o.order_list.order_list_main.5.174f1802lkyBnD It was about 20-25% of what I could get an OEM for on eBay and it looks pretty good. I bench tested it with the 12V off my battery and it works. Unfortunately for me, it turns out that I have no power getting to the actuator itself so I probably bought it unnecessarily. With good continuity for all 5 wires from the ECU it seems that I've likely got an issue with the ECU (squeaky clean - no corrosion) or (duh) a possible fuse issue which I hadn't thought of until last night. There does seem to be a 20A diff fuse in the passenger side panel for "diff".

The Actuator ECU is actually super, super easy to get to. Just pull off the triangular passenger footwell interior panel first of course. A black plastic cap towards the front just yanks right off and then you pull the panel directly towards the back of the truck. Then you flip upside down in the foot well and will see 89533-60090 hiding in a void behind a beige coloured bracket (holding up a lot of wiring and other modules). The ECU location is right against the firewall and will pop right out of the metal bracket see in your example photo.

Well, I have fixed 2 out of 3 problems.

I bought a used ECU for like 30 euro and it seems to work, although I won't be sure until all 3 issues are fixed. At least I'm now getting a flashing diff lock indicator, whereas before it was completely dead. So if I were you, I'd look for a used ECU - they are cheap.

Local car electrician fixed the broken harness issue, so now there's continuity from the ECU to the actuator.

Tomorrow I'm driving to a guy who sells and installs actuators. It's gonna be a chinese one, because OEM is just outrageously expensive for what it is. Another shop suggested to install a pneumatic actuator instead, bu the total was close to the price of OEM actuator, so I passed on it.

But there's more. Last week I drove quite far to a so-called specialist who said they are gonna take a look at the existing actuator and if possible rebuild it. Unfortunately they said that the actuator was too far gone, so replacement was needed. I saw it myself, it looked like it was in a rough shape indeed. These guys took out the actuator and temporarily covered the hole with a metal plate. I found that suspicious, but they said it's all good, they did it all the time. Half way home the diff lock engaged by itself, apparently since there was no more actuator holding it in place, it just jumped to locked. I thought I was screwed, but I got lucky and found a mechanic nearby who manually disengaged the diff lock and put the old actuator back in.

So far I didn't expect there to be so much hassle for something supposedly so simple.

 

[SteveH]

@RockDriver - sounds like you're getting the full treatment here. The self-locking diff story ended well at least - now the sleeve is held in place so it won't happen again.

 

[RockDriver]

@RockDriver - sounds like you're getting the full treatment here. The self-locking diff story ended well at least - now the sleeve is held in place so it won't happen again.

Yeah. Today the actuator was finally replaced with a new chinese one. Hopefully it will hold a while. I don't expect to use it often, but I will exercise it a couple of times a month just to be on a safe side. Finally this 2 month long saga is over, or at least I hope so.

 

[porschenut]

A little update about my blinking rear differential light situation. I got as far as I could with it. Actuator seemed fine, wiring continuity was good, fuse in drivers side footwell was good. All indicators pointing to 89533-60090 ECU but I couldn’t be sure. I took it to a great shop and they confirmed my findings but also checked for a required signal coming from the centre diff lock and that was good. Final confirmation is that my 89533-60090 ECU has indeed gone bad.