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Charging Problem?


Well-Known Member
Mar 10, 2010
Country Flag
Hey Chaps, I need some advice.

Driving home from work this evening (22 mile drive) after a couple of miles I washed the screen & noticed the wipers were a bit slow, looking at the voltage indicator the needle was bang on the half way mark. I was running the aircon & the radio, so turned them off & continued driving.

I got within about 1/2 a mile from home & the needle on the voltmeter started dropping rapidly, then the charging warning light came on accompanied by a selection of other dash lights. By the time I got home nothing electrical was working at all, even with the engine running.

Both batteries have discharged to about 1.7 volts.

Does this sound like the alternator has failed or something else?

The alternator wasn't making any noise, belts are fairly new & tight. Fuse & fusible links are ok.

I'm now trying to recharge the batteries, hopefully this hasn't killed them?

Thanks in advance.
The plug on the back of the alternator has a nasty habit of working loose and over time the terminals burn and corrode, I would look there first, also check both belts again as well, I have seen mismatched belts put on and one was tight and the other loose, this caused the alternator to have a reduced output when it was need most i.e.AC/wipers/lights ect, no noise just a reduced output and off course the light stayed out inside.


Hi Dave,

Thanks for your reply, will check the terminal. The belts I replaced last year with Genuine Toyota belts which come as a matched pair. I retensioned them about 3 months ago & they're still ok.
Charged the first battery overnight & it was fully charged this morning. I'll do the second one tonight.

Has anyone got any ideas on what I should be checking once I've got the batteries back in?
OK IMHO this is how a battery should be checked.

Does the battery have checkable cells i.e. can you top them up?

If yes then get a specific gravity meter instructions come with it.

If that checks out OK then 'load' test the battery whilst watching the cells, any that bubble like mad are toast, scrap the battery and these batteries should be replaced in matched pairs.

If it is not checkable then the load method is the best guide.

Once fitted and running your charger voltage to each battery should be as near as dammit 13.8 volts and a maximum of 14.4v, of course there may be slight variations in meter accuracy but that is your best guide. These figures should be taken with all electrics switched off and a fast idle speed no more than 2000 rpm. Then switch on things one at a time and note if the reading stays pretty much around the 13.8 mark, if it does your ready to go, if not get back to the guys here on the forum.


Dave, Batteries are Toyota supplied 100% Maintenance free so no checkable cells unless I can prise the top cover off?

I've also posted on Lcool forum & a suggestion from there is that the relay controlling the inlet heater (No glow plugs on the 24 valve) may be toast. If these go wrong they can make the heater permanently on & this draws a load of 100 amps! :shock:

Obviously anr 80 amp alternator hasn't a hope in hell of keeping up with this current draw.

Only problem is I can't locate the damn relay. When I put the batteries back on tonight I'm going to disconnect the feed to the inlet heater first as a precaution, then test the charging voltage as you've suggested.
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I do not know much at all about the later versions of the 80, I understand the system though as I have seen it on many commercials and you are right it does give the battery a caning. See how you get on and report back because there are some clever people about on this forum.


I now know where to look for the relay, allegedly it lives under the offside battery tray.

I'm going to pop into the main dealers at lunchtime & see if they have any history on this being changed on my truck as apparently it was a Toyota recall due to fire risk.
Brett said:
I now know where to look for the relay, allegedly it lives under the offside battery tray.

I'm going to pop into the main dealers at lunchtime & see if they have any history on this being changed on my truck as apparently it was a Toyota recall due to fire risk.

If it's anything like the problem Toyota are having at the moment with electrics they may well blame the carpet being stuck on the throttle pedal :mrgreen:


It wasn't even as good as that Dave, just the standard Toyota response, "There is no outstanding recall on your vehicle sir" :roll:
I hate it when they do that!! :evil:

Where did you hear about the recall?, keep us informed on the battery front anyway.


Dave 2000 said:
Where did you hear about the recall

On the Lcool forum, the guy in the Toyota Garage did remember there being a recall but my truck wasn't identified as requiring it allegedly.
Holy Sh*t :shock:

I think I've had a close escape, the heater relay had totally burnt out, the wiring was burnt as well.

I've stripped the burnt wiring out of the loom & disconnected at the heater & the battery terminal, insulated it & tied back.

I've put everything back in & I'm up & running again, although I had a bit of a scare, it wouldn't start at first & I suspected more wiring had been damaged. It was actually the imobiliser had kicked in when the batteries were disconnected

I'm going to have to re-instate a relay of some description for the winter though I think:?:





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:shock: Bloody hell, that's not nice at all
I would recommend anyone with a 1HD-FT (24 Valve HDJ80) to keep a very close eye on this, apparently it is quite a common failure & potentially you could lose the whole truck due to fire.

Luckily mine failed about 1 minute from home :shock:

Don't know if the mods want to edit this post & make it a sticky as a warning?
Hi Brett. In case you had not got that repaired one of the fellas o n tlocuk did repair his with a relay from a motorbike pretty low cost too compared to yota part i recall.

Good luck in any case
Hi Adrian, Mine was all sorted under warranty by Toyota. I just had to pay a percentage of the labour. It should have been recalled but the previous owner ignored the recall letters from Toyota.

Luckily they were good enough to honour the recall.