@MuhannaGhanem Although the relays are "non-replaceable" there are other circuits that feed into the relay to trigger it, and if the relay is triggered, there are circuits that will be energized. You should be able to trace where those circuits are and monitor for voltage or absence of voltage.
2005 LX470 Main Junction Block Replacement (2 Viewers)
- Thread starter vcheng
- Start date
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[how to do this broo ??? I have no idea
@nckwltn how to do this i dont have any idea ???
Very much the same symptoms as many of you here. Discovered 3 points of leakage in the rear AC tubing and replaced 90% of the rear line with Dorman splice tubing/connectors. After that, the system was able to hold vacuum for over an hour so I started injection of refrigerant. After about 1/3 of a bottle, the vehicle wouldn't take any more and the clutch wasn't engaging. Using a electrical probe tester, I fed power to the clutch and saw it activates just fine. Onwards to my attempt at a fix.
Thanks @vcheng for the writeup. It made taking this thing apart so much easier.
I used some pliers to pinch and gently crack the relay plastic shell. Here's the innards of the relay in question:
Again, using the probe tester and applying 12v, the relay works. But the contact area for pin 30 and 87 inside the relay and the surrounding area looks burnt. I didn't have a second tester or multimeter so I was convinced the contacts were dirty and should probably replace instead of clean- especially with the relay cover broken off at this point.
Plan is to carefully cut off the relay without stressing the board/contacts under it.
It's off.
Tough little guy. Cutting the pins from inside the relay hoping to free it from the board.
More struggling... seems like post limit is 5 pics. Hopefully I can make consecutive posts without issues.
Thanks @vcheng for the writeup. It made taking this thing apart so much easier.
I used some pliers to pinch and gently crack the relay plastic shell. Here's the innards of the relay in question:
Again, using the probe tester and applying 12v, the relay works. But the contact area for pin 30 and 87 inside the relay and the surrounding area looks burnt. I didn't have a second tester or multimeter so I was convinced the contacts were dirty and should probably replace instead of clean- especially with the relay cover broken off at this point.
Plan is to carefully cut off the relay without stressing the board/contacts under it.
It's off.
Tough little guy. Cutting the pins from inside the relay hoping to free it from the board.
More struggling... seems like post limit is 5 pics. Hopefully I can make consecutive posts without issues.
It's out.
RIP old relay. Had an old Toyota relay box with a socket that fits the MG CLT relay from a pre 03. Filed down the sides.
Decided I'm going to sacrifice these spare holders and mount the relay here.
And... couldn't find an attachment narrow enough to make clean cuts. Resorted to heating a small knife and melting out a hole.
Adding some flux and solder to the contacts on the board.
Soldering the pigtail wires from the relay holder, matching each pin to the relay's orientation. Cleaned up the flux after with alcohol and an old toothbrush. Not the best soldering skills. Having a weak soldering iron didn't help.
More hot knife welding...ugly but it'll have to do.
Routing wires through here.
And careful not to pinch anything when reattaching the top cover.
Soldering the pigtail wires from the relay holder, matching each pin to the relay's orientation. Cleaned up the flux after with alcohol and an old toothbrush. Not the best soldering skills. Having a weak soldering iron didn't help.
More hot knife welding...ugly but it'll have to do.
Routing wires through here.
And careful not to pinch anything when reattaching the top cover.
Almost forgot these 4 screws under... screwdriver is pointing to one.
Screwdriver pointing to the U-clip. This one got me stuck for a bit...it's release from the top side. I did it by wiggling a precision flathead between the U-clip leg and the tab holding it place...while pulling the clip from the bottom.
Here's the artwork:
Fully assembled. Fuse box lid closes without any clearance issues.
Screwdriver pointing to the U-clip. This one got me stuck for a bit...it's release from the top side. I did it by wiggling a precision flathead between the U-clip leg and the tab holding it place...while pulling the clip from the bottom.
Here's the artwork:
Fully assembled. Fuse box lid closes without any clearance issues.
And...it didn't fix my issue. I tested the leads and I'm getting 12v from 2 pins and ground from 1 pin. I realized the relay switches the ground and not the 12v to trigger the compressor. Going back to read the AC codes from the dash of 21 and 23...I decide to check what might have caused the car to think there's a pressure issue.
Research leads me to the trinary switch being bad. I locate the switch/sensor...which is right at the front behind the bumper. And...it isn't even connected. I popped it back in and compressor kicks on. After filling whats left of the 3 original bottles of refrigerant I got, AC is blowing strong and cold. I didn't even need to mess with the relay...but I guess I have it accessible now just in case.
Important Note: About wires not being pinched and possibly shorting something/causing further damage, the wires from the relay holder was routed through this hole and not directly down... 2 metal rails under there so I had to be extra careful.
Research leads me to the trinary switch being bad. I locate the switch/sensor...which is right at the front behind the bumper. And...it isn't even connected. I popped it back in and compressor kicks on. After filling whats left of the 3 original bottles of refrigerant I got, AC is blowing strong and cold. I didn't even need to mess with the relay...but I guess I have it accessible now just in case.
Important Note: About wires not being pinched and possibly shorting something/causing further damage, the wires from the relay holder was routed through this hole and not directly down... 2 metal rails under there so I had to be extra careful.
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What a twist to the story!
My issue wasn't the ac relay, but one related to the alternator, good to know that if my contact sanding job gives out. There is an "easy" fix!
My issue wasn't the ac relay, but one related to the alternator, good to know that if my contact sanding job gives out. There is an "easy" fix!
- Thread starter
- #70
Note to self: Check pressure switch before going all ballistic on the relay.
Having said that, I am glad that we now have a workable solution to replacing relays on the supposedly non-serviceable junction box. Many thanks!
cruiserbrett
GOLD Star
I believe I identified the relay and found a suitable solder in replacement. (Made in Japan, but not Denso)
Anyone have a spare fuse box sitting around after replacing? Would like to figure out if the relays I sourced will work. Happy to pay for fuse box/shipping.
Anyone have a spare fuse box sitting around after replacing? Would like to figure out if the relays I sourced will work. Happy to pay for fuse box/shipping.
cruiserbrett
GOLD Star
I’ll let you know when they arrive. I’ll send some your way to check.
cruiserbrett
GOLD Star
Here they are:
I am really grateful to the OP and others for this post. I was having the same problem with my AC. The main fuse block today (September 2023) has inflated to over $700 plus shipping. I was loathed to spend that money, and not know for sure if it was fixed until after the part was installed. I ended up cutting out the offending relay with a Dremal tool and soldering in a pig tail to accept a cheap universal automotive relay... Success, my AC is working great again!
