Front Power Distribution Fuse Box
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From: Sunshine Coast QLD
Front Power Distribution Fuse Box
Does anyone have any pictures of the Front Power Distribution Fuse Box circuit board from an XJR
Im interested in Relay 12, which has failed
Relay 12 powers the heaters on the four O2 sensor's
I have conformed it is not the earth or the sensors
No power is present at Fuse 33 and 34
The result is generating codes P0037, P0057, P1646, P1647
Im looking at repairing Relay 12 rather than replacing the fuse box.
Im just looking for a pic of the pcb to get a head start before I pull the fuse box out.
Cheers
34by151
Im interested in Relay 12, which has failed
Relay 12 powers the heaters on the four O2 sensor's
I have conformed it is not the earth or the sensors
No power is present at Fuse 33 and 34
The result is generating codes P0037, P0057, P1646, P1647
Im looking at repairing Relay 12 rather than replacing the fuse box.
Im just looking for a pic of the pcb to get a head start before I pull the fuse box out.
Cheers
34by151
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Joined: Nov 2009
Posts: 3,145
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From: The beautiful Mornington Peninsula in OZ
Hi
I have a spare fuse box. Without checking I think it is a rear one and the Jag model is
unknown but it is for an x350.
Removing the pcb is easy it just clips in but there are two soldered together with pins
about 1 cm apart. There are many, many pins.
Personally I would not attempt to separate them to gain access to the non servicable relays
which is I assume what you want to repair. However if you have a nice modern soldering iron with a tiny anvil
(which I don't have) I guess it could be doable.
pics attached.
Good luck
I have a spare fuse box. Without checking I think it is a rear one and the Jag model is
unknown but it is for an x350.
Removing the pcb is easy it just clips in but there are two soldered together with pins
about 1 cm apart. There are many, many pins.
Personally I would not attempt to separate them to gain access to the non servicable relays
which is I assume what you want to repair. However if you have a nice modern soldering iron with a tiny anvil
(which I don't have) I guess it could be doable.
pics attached.
Good luck
Last edited by meirion1; Mar 21, 2017 at 05:26 PM.
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From: Sunshine Coast QLD
Thanks for that
From your pic they look easily repairable. Worth a go as a new one is not cheep
For now ive bypassed R12 using a standard automotive relay
Cheers
34by151
From your pic they look easily repairable. Worth a go as a new one is not cheep
For now ive bypassed R12 using a standard automotive relay
Cheers
34by151
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From: Sunshine Coast QLD
For now ive bypassed R12 using a standard automotive relay.
All working fine, no codes
This will do for a few weeks till I can pull the fuse box out and replace R12.
I dont see any need to purchase a new one as the relays are standard pcb mount ones and can be purchased and replaced easily.
Id also prefer not to use second hand fuse box as the relay in that will be well on its way to failing as well
Cheers
34by151
All working fine, no codes
This will do for a few weeks till I can pull the fuse box out and replace R12.
I dont see any need to purchase a new one as the relays are standard pcb mount ones and can be purchased and replaced easily.
Id also prefer not to use second hand fuse box as the relay in that will be well on its way to failing as well
Cheers
34by151
Junior Member
Joined: Mar 2018
Posts: 2
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From: Mesa, Az
I have seen your post regarding using a standard relay for the R12 unserviceable relay in the fuse panel. Was wondering how you accomplished that as I have no open relay slots in my fuse panel and am reluctant to use jumper wires for 33 and 34 because of their higher amperage (30 each)
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From: Sunshine Coast QLD
My solution was to strip down the fusebox and replace all the pcb mounted relays.
I know only R12 had failed but the pcb mounted relays are cheep and my thinking is if one has failed the rest cant be to far behind. So while its open do them all
As for the bypass this is how to do it as a temporary solution only
I used a standard automotive relay
The switched poles going to power and the fuses
The trigger poles to ground and F35
Relay pin 30 goes to the stud on F35 in the fusebox
Use a standard lug connector for this
Relay pin 87 goes to the socket for F33 and F34.
Use a pair of standard spade connectors for this
F33 and F34 are after relay 12 so one side of the fuse is directly wired to the o2 senor.
To work out which side check the resistance to ground. The side you want will have some resistance. The other will have none.
Relay pin 86 connects to ground.
Use a standard lug under the fusebox mounting bolt.
Relay pin 85 connects to the ign relay.
To do this remove F1 which supplies the ign power.
Put in a blade fuse tap like this one
https://www.jaycar.com.au/double-bla...e-tap/p/SF5115
The wire tap goes to the relay pin 85
Put F15 back in the tap
If your tap is like the one in the pic with 2 fuses put a any small fuse in the second position as it will be the fuse for the new relay
If you are thinking on more than a temporary fix you better add an pair inline 30A fuses to the cable running back to F33 and F34
You could also use some blade connectors on the fuse pins and and female ones to mount F15 but these taps are cheep and easy to get
Cheers
34by151
I know only R12 had failed but the pcb mounted relays are cheep and my thinking is if one has failed the rest cant be to far behind. So while its open do them all
As for the bypass this is how to do it as a temporary solution only
I used a standard automotive relay
The switched poles going to power and the fuses
The trigger poles to ground and F35
Relay pin 30 goes to the stud on F35 in the fusebox
Use a standard lug connector for this
Relay pin 87 goes to the socket for F33 and F34.
Use a pair of standard spade connectors for this
F33 and F34 are after relay 12 so one side of the fuse is directly wired to the o2 senor.
To work out which side check the resistance to ground. The side you want will have some resistance. The other will have none.
Relay pin 86 connects to ground.
Use a standard lug under the fusebox mounting bolt.
Relay pin 85 connects to the ign relay.
To do this remove F1 which supplies the ign power.
Put in a blade fuse tap like this one
https://www.jaycar.com.au/double-bla...e-tap/p/SF5115
The wire tap goes to the relay pin 85
Put F15 back in the tap
If your tap is like the one in the pic with 2 fuses put a any small fuse in the second position as it will be the fuse for the new relay
If you are thinking on more than a temporary fix you better add an pair inline 30A fuses to the cable running back to F33 and F34
You could also use some blade connectors on the fuse pins and and female ones to mount F15 but these taps are cheep and easy to get
Cheers
34by151
Last edited by 34by151; May 19, 2018 at 02:14 AM.
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From: Hazlet Township, NJ
My solution was to strip down the fusebox and replace all the pcb mounted relays.
I know only R12 had failed but the pcb mounted relays are cheep and my thinking is if one has failed the rest cant be to far behind. So while its open do them all
As for the bypass this is how to do it as a temporary solution only
I used a standard automotive relay
The switched poles going to power and the fuses
The trigger poles to ground and F35
Relay pin 30 goes to the stud on F35 in the fusebox
Use a standard lug connector for this
Relay pin 87 goes to the socket for F33 and F34.
Use a pair of standard spade connectors for this
F33 and F34 are after relay 12 so one side of the fuse is directly wired to the o2 senor.
To work out which side check the resistance to ground. The side you want will have some resistance. The other will have none.
Relay pin 86 connects to ground.
Use a standard lug under the fusebox mounting bolt.
Relay pin 85 connects to the ign relay.
To do this remove F15 which supplies the ign power.
Put in a blade fuse tap like this one
https://www.jaycar.com.au/double-bla...e-tap/p/SF5115
The wire tap goes to the relay pin 85
Put F15 back in the tap
If your tap is like the one in the pic with 2 fuses put a any small fuse in the second position as it will be the fuse for the new relay
If you are thinking on more than a temporary fix you better add an pair inline 30A fuses to the cable running back to F33 and F34
You could also use some blade connectors on the fuse pins and and female ones to mount F15 but these taps are cheep and easy to get
Cheers
34by151
I know only R12 had failed but the pcb mounted relays are cheep and my thinking is if one has failed the rest cant be to far behind. So while its open do them all
As for the bypass this is how to do it as a temporary solution only
I used a standard automotive relay
The switched poles going to power and the fuses
The trigger poles to ground and F35
Relay pin 30 goes to the stud on F35 in the fusebox
Use a standard lug connector for this
Relay pin 87 goes to the socket for F33 and F34.
Use a pair of standard spade connectors for this
F33 and F34 are after relay 12 so one side of the fuse is directly wired to the o2 senor.
To work out which side check the resistance to ground. The side you want will have some resistance. The other will have none.
Relay pin 86 connects to ground.
Use a standard lug under the fusebox mounting bolt.
Relay pin 85 connects to the ign relay.
To do this remove F15 which supplies the ign power.
Put in a blade fuse tap like this one
https://www.jaycar.com.au/double-bla...e-tap/p/SF5115
The wire tap goes to the relay pin 85
Put F15 back in the tap
If your tap is like the one in the pic with 2 fuses put a any small fuse in the second position as it will be the fuse for the new relay
If you are thinking on more than a temporary fix you better add an pair inline 30A fuses to the cable running back to F33 and F34
You could also use some blade connectors on the fuse pins and and female ones to mount F15 but these taps are cheep and easy to get
Cheers
34by151
Thread Starter
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Veteran Member
Joined: Jan 2012
Posts: 1,174
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From: Sunshine Coast QLD
Sorry no pics
As I said I did it as a temp fix. It was only in the car while I was getting ready to fix the fusebox.
If you check the electrical diagram all this is doing is replacing the on board relay
The locations I gave you are the same as R12 uses.
You are just tapping into where these are accessible from the top of the fusebox
When I did it I did not use a fuse for the power supply to the O2's as it was a temp fix while I got replacement pcb relays
There is no reason you cant leave this in place provided you use a pair of 30a fuses between the relay and the sockets for F33 and F34
To fix the fusebox itself this is what I did
1. Remove the fuse box from the car
2. Remove the relays and fuses
3. Remove the 2 plastic covers
4. You will now have the 2 circuit boards. Take a measurement of distance the boards are apart (you need this latter)
5. Cut the links on the outside of the boards and separate them
6. Desolder the cut links. (I will give you a few ways to do this at the end)
7. Solderer the relays
8. Solder in the replacement relays
9. Cut a bunch of solid wire aprox 50mm long.
From memory I used 4mm building wire
10. Solder the cut wires into the pins on the upper board
11. Put the 2 boards together. This will take some time and patience getting them all to line up.
12. Now you have the 2 boards to together get the boards at the correct spacing. Use the measurement from step 4. For now get the spacing close and get one corner perfect. Solder that corner
13. No get the spacing right on the next corner and solder that. Repeat for each corner
14. Double check the spacing and adjust if needed
15. Solder the rest of the pins
For Desoldering the best thing to use is a desoldering gun
Assuming you dont have one her are a few tips
Heat the boards with a heat gun and pull the remainder of the pins with needle nose pliers.
No use solder wick and a soldering iron to clean up the pads.
Once you have done that inset your solid wire and check the hole is clear
Cheers
34by151
As I said I did it as a temp fix. It was only in the car while I was getting ready to fix the fusebox.
If you check the electrical diagram all this is doing is replacing the on board relay
The locations I gave you are the same as R12 uses.
You are just tapping into where these are accessible from the top of the fusebox
When I did it I did not use a fuse for the power supply to the O2's as it was a temp fix while I got replacement pcb relays
There is no reason you cant leave this in place provided you use a pair of 30a fuses between the relay and the sockets for F33 and F34
To fix the fusebox itself this is what I did
1. Remove the fuse box from the car
2. Remove the relays and fuses
3. Remove the 2 plastic covers
4. You will now have the 2 circuit boards. Take a measurement of distance the boards are apart (you need this latter)
5. Cut the links on the outside of the boards and separate them
6. Desolder the cut links. (I will give you a few ways to do this at the end)
7. Solderer the relays
8. Solder in the replacement relays
9. Cut a bunch of solid wire aprox 50mm long.
From memory I used 4mm building wire
10. Solder the cut wires into the pins on the upper board
11. Put the 2 boards together. This will take some time and patience getting them all to line up.
12. Now you have the 2 boards to together get the boards at the correct spacing. Use the measurement from step 4. For now get the spacing close and get one corner perfect. Solder that corner
13. No get the spacing right on the next corner and solder that. Repeat for each corner
14. Double check the spacing and adjust if needed
15. Solder the rest of the pins
For Desoldering the best thing to use is a desoldering gun
Assuming you dont have one her are a few tips
Heat the boards with a heat gun and pull the remainder of the pins with needle nose pliers.
No use solder wick and a soldering iron to clean up the pads.
Once you have done that inset your solid wire and check the hole is clear
Cheers
34by151
Last edited by 34by151; May 19, 2018 at 02:14 AM.
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Posts: 753
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From: Hampshire, UK
My front fusebox in my 2004 Super V8 went wrong at Christmas and the car needed recovering. The dealer diagnosed the fusebox and I think a new one was around £550, I found a used one on ebay for £60 so they just fitted that one for me, I kept the old one purely for all the fuses and relays in it that may be useful in the future
