Voltage, alternator, dash warning

[localshop]

It's an 07 yaris zinc mmt [Please don't - I inherited it ]

Driving along and all sorts of warning lights come on starting with 'battery charging' which soon disappears. I get almost home before almost everything stops. Power steering gone, won't change gear - the lot.
I get a tow home
I figure what connects all the faults is 'electrics'
The battery is a bit ancient so I pop another battery in and all is good - fires up and drives like a new one.

except
voltage as indicated by little plug voltmeter in the 12v socket is less than 12v when we're running [Little plug in voltmeter looks fine when plugged into another car]. Switch on headlights, ac and heated screen and it drops to 11.2v

There's no dashboard 'not charging' warning illuminated BUT - switching off and switching on again reveals the 'not charging' warning light doesn't seem to be working

I start by trying to change the bulb in the 'not charging' warming only to find the warning lights are all little LEDs on a circuit board.

I've replaced the Alt s fuse

Any clues where to go next other than 'get the alternator changed' which I've thought of already.

Many thanks in anticipation.

[nortonfb]

Check the output of the alt. Should be above 13.5V
Check belt tightness.

[localshop]

Looks like alternator is pooped
I'm guessing the dashboard instrument cluster warning LED is gone too
Suppose I'll have to get a new complete instrument cluster
Oh the joy

[BLH]

You may want to try the alternator first.
If the regulator is part of it like on my 2007. It is what controls the charging indicator. It is also possible the whole display is being effected by low voltage.

[localshop]

Cheers BLH
Fingers crossed that fixing alternator fixes the dash warning - but that seems counter-intuitive to me.
I don't see the dash warning as 'essential' to replace if it's ££££ I'd be happy with a little voltmeter running off the cigarettte lighter

[06YarisRS]

I think BLH is right. Low voltage in these cars can cause a plethora of problems. He mentioned the voltage regulator. They are prone to corrosion. You [I]can[I] just buy a regulator and replace it. That said, alternators aren't that expensive for these cars. I just replaced my alternator rather than switching out the regulator.

[localshop]

Bit the bullet and 'got it done'

There were 2 types supposed to fit on ebay
one with a 'side to side' orientated connector block socket and the other 'front to back'. Advised by a seller with lods of +ve feedback I bought a front to back to replace a side to side - but it looked to me like there wasn't enough slack in the wiring to pull the connector around and I couldn't 'give it a go' because returns were only accepted if not fitted so I returned it. It was about £120

It became quite urgent to get the car back on the road. Toyota were asking silly money and couldn't do the job for weeks. ATS wanted £500+ for the part. Local garage wanted £320 for the part and local Halfords said they could replace for £320 [parts and labour] but they couldn't do it for 2 weeks. Next nearest Halfords said they could do it tomorrow for £360 - and they price matched their other branch. Dropped off at 0900 and job done just after 1100.

oddly - now the alternator works the 'battery charging' warning on the dash is there again, by which I mean it's on when do first turn of ignition key and goes off when the engine starts. i'm left wondering what kind of person designs a 'warning light' that doesn't work when you need it most. I've got a cigarette lighter voltage display in at the mo - I think I'll leave it in.

Thanks for the helpful comments

[BLH]

Normal. Until the alternator starts charging. The indicator is On.

It shows the indicator is working OK. Along with a few of the other indicators. That also light until the car is started.

[localshop]

My experience was that when the alternator didn't work there was no 'battery' warning 'on' when you made first turn of key or when you started the car; I thought the 'bulb' was gone, but when the alternator was replaced it operated as you [and the handbook] describes.

[BLH]

I could see a defective alternator not lighting the warning light.

I have one of the reading on my ScanGuage reading the system voltage. Nice to know.

[localshop]

I could see a defective alternator not lighting the warning light.

I have one of the reading on my ScanGuage reading the system voltage. Nice to know.

Seems bonkers to me that the time you most need a 'not charging warning' the 'not charging warning' doesn't work ...........

I'll be fitting a mini voltage display from the cigarette lighter