Battery or alternator? Which do you think?

rich1068 · November 14, 2020

Went for a little run out in the Peaks this afternoon, nasty weather so lights on, stereo on, wipers on and I noticed my wipers were slow as well as the 'lights on' indicator being a little dim. Apart from that everything appeared normal and I didn't really give it a thought.

Fast forward to me pulling up in the supermarket car park and I noticed I'd got an array of dim warning lights (just about all of them) but the car still running OK. Car started fine when I came back to it but again after 10 minutes all the hazy lights were back. Also the steering wheel didn't extend/retract with the ignition. Everything electrical is extremely slow so I assume the Battery is virtually drained.

So..... Battery or alternator? Unfortunately I don't have the tools to test the current state of the Battery or whether the alternator is putting the charge back in but wondered if these symptoms told you anything? These things always happen at a weekend so I'm a bit stuck until Monday but did wonder what you thought.

Things to note: In the last fortnight or so I have had the cam belt, aux belt changed. On Friday I accidentally left both front interior map lights on for an hour or two and I'm aware that little things can just tip a Battery over the edge. I have a feeling this is an alternator issue but I am aware that little things can tip a Battery over the edge. This one came with the car, has no dates on it and is a brand I've never heard of.

Many thanks.

[edit] Should also add that I've had the PAS pump changed due to another issue but there were no signs of leaks onto the alternator. [/edit]

Spacewagon52 · November 14, 2020

Eliminate the Battery as a cause first. Can you put another Battery on temporarily to see if it makes any difference?

ColinBarber · November 14, 2020

It could be either but given the Battery is essentially a consumable item you should assume it as the likely cause and check that first.

If you start the engine and switch on the headlights, does the brightness increase if you rev the engine - that indicates the alternator is at least doing something.

rich1068 · November 14, 2020

10 minutes ago, Spacewagon52 said:

Eliminate the battery as a cause first. Can you put another battery on temporarily to see if it makes any difference?

I don't have another unfortunately.

2 minutes ago, ColinBarber said:

It could be either but given the battery is essentially a consumable item you should assume it as the likely cause and check that first.

If you start the engine and switch on the headlights, does the brightness increase if you rev the engine - that indicates the alternator is at least doing something.

If it'll start I'll give that a go.

Electrics aren't really my forte. As you may have gathered.

Herbie · November 14, 2020

The Battery is only used for cranking the engine. Once it's running and the alternator is spinning it's the alternator that supplies all of the electrical demands and charges the Battery back up, so first thought is the alternator is dying.

Having said that, batteries do fail and/or wear out more often than alternators do. Without proper testing and diagnostics it's all a bit of a guessing game really.

EDIT: Without any electrical test gear I'd go one further than Colin above - switch on headlights (main beam), heated rear window etc., etc., to give a heavy load. If the lights visibly brighten when revving the engine then it would be safe to assume the alternator is giving a good output.

hockeyedwards · November 14, 2020

Without test gear you'll have to come up with your own diagnostic routine haha, but you can buy super cheap testers from plenty of DIY places and always good to have.

Above was my first thought as well to rule in or out the alternator, max load it and if it starts to die, rev engine and it would give an indication of its function, or lack of!

Noted your PAS comment, might just be a bad coincidence!

Tinonline · November 14, 2020

How old is the Battery...🧐

Also I’ve flattened the Battery a few times working on the car with doors open and internal/boot/lights on much to my surprise...all good afterwards though.

Barry14UK · November 15, 2020

I don't think you can do more than has been suggested here without getting a tester. You, could drive a mile or so and listen to a bit of music until the car won't start and then call the emergency services out if you are a member. They will then get you going and advise if it is the Battery or alternator that needs replacing.

rich1068 · November 15, 2020

As previously mentioned, I don't think this car has had much use over the last few years and suddenly getting driven daily is making these bugs appear. Hopefully this will be one of the last!

21 hours ago, Herbie said:

The battery is only used for cranking the engine. Once it's running and the alternator is spinning it's the alternator that supplies all of the electrical demands and charges the battery back up, so first thought is the alternator is dying.

Agreed. My thoughts too.

19 hours ago, hockeyedwards said:

Without test gear you'll have to come up with your own diagnostic routine haha, but you can buy super cheap testers from plenty of DIY places and always good to have.

Remembered today that I do have a tester of sorts. Unfortunately it's at the office but I have one of those Bluetooth/FM transmitters that plug into the ciggie lighter. Like others I've had it also displays voltage pre and post start up.

18 hours ago, Tinonline said:

How old is the battery...🧐

Unknown I'm afraid. It came with the car and there aren't any date labels on it.

14 hours ago, Barry14UK said:

I don't think you can do more than has been suggested here without getting a tester. You, could drive a mile or so and listen to a bit of music until the car won't start and then call the emergency services out if you are a member. They will then get you going and advise if it is the battery or alternator that needs replacing.

My cunning plan (not very cunning at all) is to give Lexus Breakdown a call tomorrow. They can confirm either way, hopefully get it started and then I'll get it over to Lex-Tek where it can wait until I've sourced an alternator. If it turns out it's just the Battery then I'll just pick one up or they supply one. Not likely though.

Tinonline · November 15, 2020

Battery prices are ok at the dealerships...I think the units are good for 5 years...mine is over that now but I’m not making any comment😷🤭

rich1068 · November 15, 2020

Still holding out it could be this simple but I fear it won't be.

Spacewagon52 · November 15, 2020

Yes go to Lexus if you need a new Battery. Cost is very reasonable - well it used to be!

Get a quote

rich1068 · November 16, 2020

Confirmed by Lexus Assistance (the AA) as the alternator. I did manage to get it started with a view to getting it to Lex-Tek where it could sit until I sourced the part but barely made it a mile down the road. AA came, put on a fresh Battery to get me going and followed me to Dave's. Stirling service from the AA as usual and incidentally the 5th time I've used them since 2017 but the first time for a Lexus.

Trying to find a part now.

Malc · November 16, 2020

1 hour ago, rich1068 said:

Trying to find a part now.

this January mine came from Auto Electric Co @ £298.48 .............. replaced the original at 227,482 miles

Malc

rich1068 · November 16, 2020

Funnily enough I've just got off the phone with Euro Car Parts. They can do me a reconditioned Lucas exchange unit for £163! I snapped their hand off.

It might not be the best but at least it's from a bricks and mortar store and there's some come back if it breaks.

Spacewagon52 · November 16, 2020

2 hours ago, rich1068 said:

Funnily enough I've just got off the phone with Euro Car Parts. They can do me a reconditioned Lucas exchange unit for £163! I snapped their hand off.

It might not be the best but at least it's from a bricks and mortar store and there's some come back if it breaks.

That sounds a good buy! How much from Lexus, dare I ask?

rich1068 · November 16, 2020

400ish plus VAT I think. Can't really remember because it was really just the part number I was after. Moot point anyway because it's unavailable. £1k+ from Amayama but that wouldn't have materialised either. So because they're not available the non genuine route is the only one to take. Your model would be a bit more. Around £300 plus VAT from ECP.

Malc · November 16, 2020

5 hours ago, rich1068 said:

Euro Car Parts

I wonder if they have a centralised store ............. they couldn't supply me with one back in January, bet they ordered one up from somewhere and you're the lucky guy who's got the one intended for me as an afterthought and they've had to wait another 11 months to find a buyer ! ...... and it's a " gift " to you at £163

There aren't going to be too many Mk3 owners wanting an alternator for sure

Malc

rich1068 · November 16, 2020

Well there's still a chance it could be the wrong one. The one for the MK3 is different to the more widely available one for the MK4 though both are unavailable from Lexus. There are also two different alternators listed for the MK3, one rated at 80A and one rated at 100A. The 100A was also revised during production but the part number for the substitute went down rather than up which I'm told is unusual. On top of all that, suppliers ask me for my registration first which never brings up anything because my car spent so long in the Isle of Man it lost its original reg and had a period one issued.

As you can see I've learned a lot about alternators in the last couple of days!

Herbie · November 16, 2020

If the car isn't a daily driver and you can spare a bit of off-road time, why not either repair the alternator yourself or send it away for repair so you don't need to mess about with part numbers and risking getting the wrong one?

Ribblesdale Auto Electrics where I live in Preston are excellent for this very thing and well worth a call on 01772 796047

rich1068 · November 17, 2020

It is a daily driver but this will be the route I'll take if the ECP part is wrong. In fact before they came up with one I called at an auto electrician in Sheffield that I've used before and that specialised in this sort of thing only to find he retired last year.

Spacewagon52 · November 17, 2020

19 minutes ago, rich1068 said:

I called at an auto electrician in Sheffield that I've used before and that specialised in this sort of thing only to find he retired last year.

Very inconsiderate of him!

rich1068 · November 17, 2020

Extremely. I use him every 30 years, regular as clockwork. Country's going to the dogs.

rich1068 · November 18, 2020

All sorted. Alternator was a perfect fit and hopefully I won't need a new Battery though I'm keeping an eye on it.

Usual excellent service from Dave at Lex-Tek.

I'll post up the ECP part number later in case anyone needs it in the future.

rich1068 · November 19, 2020

ECP part number for what we refer to as the MK3 LS 400 is 401820111 https://www.eurocarparts.com/search/401820111

As you can see it shows as unavailable but just speak to a branch.

Have to say that with the replacement PAS pump and alternator the car is extremely quiet again. Both must have been on borrowed time for a little while. Could just be speculation but it's possible the original pump had been leaking onto the original alternator and the clean up the engine bay received prior to sale hid this. I remember when I picked it up the PAS reservoir was low but I just topped it up and didn't give it another thought.