FJ45 Battery and electrics confusion

LegoCruiser

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Aug 9, 2018
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So I have started poking around with my FJ45 and have so far replaced the alternator (picture 1) in the hope it solved my battery problems. That isn't really clear yet and I think the dual battery set up is not quite right. The vehicle has two batteries - one was dead when I went to view the vehicle and so I asked the seller to replace it which he did. But as I found out on the drive home the batteries weren't charging and so the vehicle died 20km from home - hence the new alternator.

The batteries are shown below (picture 2), the black one at the top is a "starter" battery and can hold charge at 12.5V (though I haven't been brave enough to drive the vehicle around yet so don't know if the alternator is charging it properly).

The other grey one below is a "leisure" battery and was the new one that the seller replaced. It is now totally dead and won't accept a charge at all. I had thought that this second battery was used for the winch, but those cables were connected directly to the starter battery (I have now disconnected them to keep things as simple as possible). The grey battery has a bunch of yellow and red wires connected to it and it could be that they connect to a now disabled alarm system (which activates when lifting the bonnet) but I haven't been able to trace them everywhere so don't really know. This second battery seems to be routed via a round thing mounted on the inside of the wing near the staring coil, but I haven't been able to work out what it is (second picture). I disconnected both connections from it but you can hopefully see the thick black cables from positive and negative terminals connect directly to this part, which can be seen on Picture 2. It has another smaller red cable attached to it which connects to the starting coil. I have looked at the wiring diagrams in the Haynes manual but can't seem to work out what this could be - maybe as I am not entirely sure which diagram to use (it's a 1982 LC but the diagrams are for various years in the 1970's but not later).

I wonder if:
1. I can simply remove the second grey battery completely, perhaps reconnecting all the cables that were attached to it to the black starter battery?
2. What is the thing that the second battery is connected to mounted on the inside of the wing?

Many thanks for any help
 

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StarCruiser

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Hi, not sure on question No1, but in answer to Q2, the round thing is a Durite (make) or similar solenoid (big relay) that links the two batteries or should when the vehicle is running in order to charge the second battery. A bit crude tbh but depends what is controlling it.

12.1v is low but if you do mean 200rpm, A) that’s an amazingly low idle speed, and B) it’ll need revving a bit to kick in. If you mean 2000 rpm then the alternator is not charging. It should be putting out 14.4v. Some of these trucks have external regulators and some have been altered to use a standard alternator with an internal regulator. Sounds like it all needs going through and stuff removing that’s not used. Plus all those small cables coming from the battery are a fire waiting to happen without fuses close to the battery. You’d be wise to disconnect them, both for the above reason and to enable you to trace them (‘what just died when I disconnected that?’)
 
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LegoCruiser

Active Member
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I am in sweden
Aug 9, 2018
55
12
8
Hi, not sure on question No1, but in answer to Q2, the round thing is a Durite (make) or similar solenoid (big relay) that links the two batteries or should when the vehicle is running in order to charge the second battery. A bit crude tbh but depends what is controlling it.

12.1v is low but if you do mean 200rpm, A) that’s an amazingly low idle speed, and B) it’ll need revving a bit to kick in. If you mean 2000 rpm then the alternator is not charging. It should be putting out 14.4v. Some of these trucks have external regulators and some have been altered to use a standard alternator with an internal regulator. Sounds like it all needs going through and stuff removing that’s not used. Plus all those small cables coming from the battery are a fire waiting to happen without fuses close to the battery. You’d be wise to disconnect them, both for the above reason and to enable you to trace them (‘what just died when I disconnected that?’)
Yes I meant 2000 rpm. Many thanks for the advice - I have started tracing back some of the wires, none of it seems to be essential as since the grey battery is dead they get no voltage even when running. I suspect there is cabling for the bonnet alarm and maybe the LPG system (also in operable), and other things like stereo, rear heater (also removed). So I may not end up with anything to connect later. The solenoid was in a poor state when I removed it, taped on lid and crusty inside so that would explain the lack of charging in the secondary battery.
Cheers!
 

Rodger

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Being originally an Australian FJ and I think you have the Haynes manual number 92055(313) use the '78 wiring diagram and not the US one for 82. If you don't have that manual let me know.
The second battery is irrelevant as that FJ is 12volt. I think the 2nd battery was added later - sorry only when I saw the mounting position did it start to ring bells as they were not mounted next to each other.

Hope that helps

Regards,

Rodger
 

LegoCruiser

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I am in sweden
Aug 9, 2018
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Being originally an Australian FJ and I think you have the Haynes manual number 92055(313) use the '78 wiring diagram and not the US one for 82. If you don't have that manual let me know.
The second battery is irrelevant as that FJ is 12volt. I think the 2nd battery was added later - sorry only when I saw the mounting position did it start to ring bells as they were not mounted next to each other.

Hope that helps

Regards,

Rodger
So I have the 92055-7B8 manual with a purple cover. I couldn't find a '78 wiring diagram - but there is a FJ45 1975 onwards. The colours of the wires don't seem to match up so well but given the crazy mess of things that's been added maybe that's to be expected. I removed around 20 metres of the stuff that led from the second battery (now removed) to a 12V power outlet in the passenger part, the stereo and the alarm system. So if it were a 24V system would the batteries have been mounted either side of the engine? The battery tray does accommodate two batteries so maybe that is not original either.

I found a couple of 5A fuses broken that were in the cable from the fusible link into to the cab - maybe to the Ammeter? I replaced them but the ammeter still makes no movement and the voltage from the running alternator is still no better. I also removed and cleaned up the terminal connections, and an earth lead from the -ve to the engine block. There is a second earth from the same terminal to the chassis but I left that one. II'd like to eliminate the battery as an issue - it's definitely old and doesn't hold charge well anyway. I'm thinking a Bosch S4026 might be a good investment rather than a super cheap one. But presumably that isn't the main issue as the voltage from the alternator should still be higher than 12.4V even if the battery is not fully charged (that's the whole point of the alternator isn't it?). So my last idea is that somehow the external regulator is the issue. I have an Ingram 831231 temperature compensated adjustable one (See pic). Not sure how to test it's functionality but it seems again it isn't original so any advice on how to test it or what to replace it with if needed would of course be very welcome.
 

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Rodger

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FJ45 wiring disgram 1982 below.
Unfortunately it is US model but I'll keep looking for a non-US spec one. It maybe worth your exploring some of the Oz 40 series forums as there are some very knowledgeable guys out there.

fj45 82 wiring dia.jpg


fj45 82 wiring dia p2.jpg


Hopefully this is some help

regards,

Rodger
 

LegoCruiser

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Aug 9, 2018
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Thanks Rodger - it seems I did have that one in the version of Haynes I have. It set me off in the right direction and with the help of another forum at ih8mud I found my solution!
77 FJ40 Alternator/Wiring Question - [Leaving Land Cruiser Club]

I found that voltage in the cable running up to the alternator from the regulator was not high enough and do I took a look at the regulator more closely. I opened it up and it did not look very nice and clean inside plus it contained a 3A fuse that had blown. I replaced it and refitted and bingo - higher at the battery and higher at the alternator B post! The only issue was then the belt started screeching when I increased the revs. My guess is that with the alternator now needing to charge it was harder to spin round and the belt was too loose. I adjusted it and now it all seems fine. Big relief. I thought I’d be chasing old wiring which I did for a bit. I’ve ordered a new regulator anyway as I don’t like the look of the existing one.CAD1865B-4A82-4830-B605-9931FCA7576F.jpeg79EEEC1D-D53C-44E6-85F5-B3E3A8E8CBD2.jpeg
 
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