BJ40 wiring harness schematic (1 Viewer)

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RopeDope

RopeDope

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Jul 13, 2015
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I'm looking for a wiring harness schematic to help solve a few electrical gremlins on my 1979 European BJ40. Have resolved a few issues with the wiring diagram from the manuals obtained of here which have been a great help. What I want is the layout of the harness showing the plug connectors to help identify what should be connected to something and what is redundant. Lots of spare plugs on the harness itself with no idea if they should or shouldn't be connected. No horn relay - sort of hot wired the horn but it works.
Example - no connections to brake pressure sensors on bottom of master cylinder but can't see any wires, spare wire next to oil pressure indicator - what is it? I have replaced the fuse box with a modern blade type as this was rather melted.
Thought this may help first, rather than photos of random connectors asking what this is for. PO did a butcher job in places, even using household wire in places. Removed a carrier bag full of redundant cable so far where he had hacked into the original and bypassed. Slowly getting there, everything works that I think needs to work but just for peace of mind I want to see what's not needed.
Cheers.
 
Hope these pictures help? For brake sensors theres red/white wire comming from driver side wiring harness. I´m not sure if you mean that another sensor for the oilpressure sensor wiring?
IMG_20160216_103524-800x600.jpg
IMG_20160216_103608-600x800.jpg
 
Cheers Beejii
That's the ones I'm looking for to start with. Will have to look around the washer bottle for any stray wires, as this was the area where the PO had created a birds nest of wiring and relays. And see if I have a spare sensor in my block. What year is your BJ?
Just noticed diesel bubbling from the middle of one of my glow plugs this morning so off to sort that out first. Might catch the order with Megastore before they ship it today and have some new ones added.....
 
Mine is allso -79.
You should definately change that glow plug, they are pretty inexpensive.
 
Can't find any spare wires for the brake cylinder sensors. Will strip harness covering back and look for cut wires. As for the extra oil sensor. It's plugged off. Time to check the service manual to see what should be there.....
image.jpeg
 
Im not sure what is the purpose of that second oil sensor, i was wondering it myself when i replased my alternator. My oilpressure cauge seems to work so its all good so far.
 
Just found out from an old Lostmarbles post that it's the low pressure engine cut-off sending switch.
So anybody. Do I need it?

Also still after the wiring schematic for the odd plug connector if anybody has one I would appreciate it.
 
RopeDope said:
Just found out from an old Lostmarbles post that it's the low pressure engine cut-off sending switch.
So anybody. Do I need it?
Click to expand...

Since it is the low pressure engine cut-off switch it is not critical to the running of the motor. BUT, it is a system that can save the motor in the case of something happening to cause a sudden catastrophic oil pressure loss (broken external oil hose, or ?). I've never been in this situation, but have read of others who have and have had the motor saved due to this switch.

Don
 
Don't know if you NEED it or not but an engine cut-off for low oil pressure sounds like a good idea to me unless Toyota's implementation of it was problematic?

All FJ40's, especially gassers, should have that feature. It would be super easy to add it to any truck. Just need an oil pressure sending unit with a set of contacts that closes when X amount of oil pressure is present and opens when it's X PSI below that pressure. Would need a pretty wide hysteresis to compensate for low RPM and worn engines.

Due to the number of seized engines I have read about over the years due to not getting the dizzy installed correctly I'm surprised that some one has not already designed such a thing.
 
I have photocopy of factory manual for -81 and if i remember correct it has wiring schematic in there? Not sure if theres differences between -79 and -81 wiring, but if you want it let me know and i can scan it for you?
 
Handcannon and Coolerman. Guess it's better to cut out from low oil pressure than no oil at all, and terminal..... Will get one sourced and fitted.

Beejii - any help appreciated. The good thing with the schematic is it shows the plugs location roughly and colors so helps narrow it down a little.
 
Seems that my memory did a trick on me. There was a scematics in the manual, but they were about switch and relay locations and mostly for the 60 series cruiser that is covered in the same manual allso. There is normal wiring diagram though, not sure if it would help you but here it is anyway.
wiring01.jpg
Edit:
Oh damn, it got shrinked while posting. Dont know how to post it bigger?
 
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Oh Rudi the wiring guru......
That's just the thing I'm after. The PO did such a butcher job on the wiring, but several of your posts got me back on track. Lights, alternator, etc etc.... Still can't gat the ammeter working, passes all the tests but hey ho.....

Do you have that in better quality? If so PM me.
 
RopeDope said:
Still can't gat the ammeter working, passes all the tests but hey ho....
Click to expand...

Let me know when you're ready for this modification to get it working.

Rudi
 
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