2005 LX470 Main Junction Block Replacement (2 Viewers)

[vcheng]

So I finally bit the bullet and replaced the main engine room junction block to cure the intermittent AC operation. For this year, the AC relay cannot be replaced separately as it is built into the junction block itself.

The replacement part number is Toyota 82720-60081 with a list price of $800 and available online for around $570.

 

[vcheng]

Disconnect and remove the battery:

Disconnect the clips holding various harnesses to the block assembly:

 

[vcheng]

Remove the top cover:

Remove the four bolts holding the assembly to the engine bay, including this one hiding beneath the AC lines:

Remove the undertray by unclipping it from the main assembly and slide out:

 

[vcheng]

Lift up the junction block and remove the two bolts holding the two big connectors:

Disconnect this small yellow connector:

 

[vcheng]

The big wiring bundle is held by a large black U-clip that is released from the top. Once that is removed, the entire wiring harness is free from the junction block. The relay block can now be removed by unbolting the two small allen bolts (3 mm):

 

[vcheng]

The old and new parts side by side:

The revised part now has an 80 amp starter fuse.

 

[vcheng]

My favorite quote: assembly is the reverse of disassembly.

All done.

 

[jerryb]

how did you know you needed this? Did toyota tell you it's the magnetic clutch relay?

 

[vcheng]

how did you know you needed this? Did toyota tell you it's the magnetic clutch relay?

The AC portion of the service manual has a troubleshooting section for the "Check AC" message popping up on the display screen. It says to check the magnetic clutch for operation, and if it is okay, to check the AC relay. If the AC relay is acting up, it says "Replace engine room junction block assembly" since the relay is buried inside it and is not replaceable separately.

 

[jerryb]

I think it's great you got pics of all that. I've seen all the toyota stuff about the relay online but it's all in easy replaceable areas, except for us. I'm glad you got pics.
Thanks you

 

[vcheng]

I think it's great you got pics of all that. I've seen all the toyota stuff about the relay online but it's all in easy replaceable areas, except for us. I'm glad you got pics.
Thanks you

I am sure someone smarter than me can figure out a way to bypass the junction block and tap a few wires to put in a replacement relay for the AC magnetic clutch outside the main junction block. Why no one has done so thus far beats me.

 

[Spike555]

How is the relay not replaceable? The junction block splits, I would think it could be replaced with a generic relay of the same type if a "official" one can't be had.
Did you split the junction block? Or just R&R?

 

[jerryb]

do you know where it is in the pics?

 

[vcheng]

How is the relay not replaceable? The junction block splits, I would think it could be replaced with a generic relay of the same type if a "official" one can't be had.
Did you split the junction block? Or just R&R?

It states clearly in the FSM that none of the relays in the Main JB are replaceable, and to replace it as one unit. One could trace the wires triggering the MG CLT relay and intercept them to put in a separate relay, but that would be a project in itself. I could not find any information that indicates that the Main JB can be split further than what I have shown above to be able to replace any relays inside it, but I am willing to be edumacated.

 

[Spike555]

It states clearly in the FSM that none of the relays in the Main JB are replaceable, and to replace it as one unit. One could trace the wires triggering the MG CLT relay and intercept them to put in a separate relay, but that would be a project in itself. I could not find any information that indicates that the Main JB can be split further than what I have shown above to be able to replace any relays inside it, but I am willing to be edumacated.

Well I ask because I replaced relays in my main junction block last fall trying to figure out my electrical gremlins, I had my block split in two, cleaned with electrical contact cleaner, and I replaced several relays.
I was looking at replacing the whole block but figured I had nothing to loose by trying that first.
I do not have pictures.
I'm glad you got yours all sorted, I was just curious. Whenever someone tells me I can't do something I try to prove them wrong, especially the factory manual. Lol

 

[vcheng]

Well I ask because I replaced relays in my main junction block last fall trying to figure out my electrical gremlins, I had my block split in two, cleaned with electrical contact cleaner, and I replaced several relays.
I was looking at replacing the whole block but figured I had nothing to loose by trying that first.
I do not have pictures.
I'm glad you got yours all sorted, I was just curious. Whenever someone tells me I can't do something I try to prove them wrong, especially the factory manual. Lol

There is a Relay Block (RB) within the Main JB, where you can easily replace relays (clearly shown in photo above). There are several more inside (including the AC MG CLT relay) the Main JB itself that, according to Mr T, are impossible to replace individually.

Thus far, the AC is working great without cutting out, so I am hoping that the problem is fixed. Time will tell.




Edit: According to the FSM, the signal to fire the MG CLT relay comes in to the Main JB via a blue wire, and energizes the black/yellow wire to the AC clutch. It should be possible to use these two wires to put in an external relay powered directly from the battery, I suppose.

 

[Spike555]

You pop those clips holding the top half onto the bottom half, it then splits. Easy.

I am glad your a/c is working, I am not knocking your work.

 

[vcheng]

You pop those clips holding the top half onto the bottom half, it then splits. Easy.

I am glad your a/c is working, I am not knocking your work.

I still have the old JB, I will take a look. But why would Toyota make you dig out the JB and tell you not to replace the relays held under a few clips? Can those clips be popped out with the JB in place? Did you remove the JB or not?

 

[Spike555]

I still have the old JB, I will take a look. But why would Toyota make you dig out the JB and tell you not to replace the relays held under a few clips? Can those clips be popped out with the JB in place? Did you remove the JB or not?

I removed mine 98% of the way, there was one last connection from the bottom that I could not get undone. So the bottom stayed in and the top was off.

Why would they do that? Have you seen the price of the replacement?
My guess would be R&R time, it is probably quicker to change out the whole unit than it is to seperate it and in the "get them in get them out" game it is all about time. They do not care about saving you time or money, all they care about is making money. How do you make money? Quick turn around, volume. Make money off of quantity and having a tech tied up for 2hrs to replace a couple of $20 relays is expensive compared to having a tech tied up for two hours to replace a whole unit. That is a huge waste of a resource to replace relays. Profit on a $20 relay is going to be like $2. Yes you're still paying the labor rate, but that only covers their cost, they can't upcharge you on labor but they sure as hell upcharge on parts. 200% is a average upcharge on parts and fluids. But labor is a flat rate.
That's one of the reasons cars are modular now days, it is easier and more profitable to replace a hub assembly than it is to break down a hub, repack the wheel bearings and put it all back together.
They do not want you doing your own work, they want you taking it to the dealer, thats why they scare you with stickers that say "only use XYZ branded whatever it is" so you take it to the dealer and not to Uncle Bob's Crab Shack and Auto Repair.
They hate DIYer's. There is no money to be made off of us.

 

[bigjay850]

I still have the old JB, I will take a look. But why would Toyota make you dig out the JB and tell you not to replace the relays held under a few clips? Can those clips be popped out with the JB in place? Did you remove the JB or not?

Any luck getting it open? It would benice and helpful to all the community some info with pics. Thanks!