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The mkiv Supra Owners Club

Dash warning lights


Mk4Gaz
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Hi guys, bit of a new problem here, and unsure what it is ?

 

I was out in the car last week, and the following dash lights started randomly turning on and off, but all together.

 

cat overheat

red battery

rear light warning

yellow oil can

 

I noticed my volt gauge showing only around 13v, so suspected a charging system fault. Anywho, i've replaced the alternator today with yet another new one (I had a print out with it to show it's test results), and although my volt gauge is now showing the correct 14.4v with the engine running, the lights are still on but permanently now ?

 

I've checked error codes, and it's clear. Checked the back lights and they're all good. I know it's charging, pretty sure the oil pressure is good as it runs sweet, and the light doesn't go out if I raise the revs, and I don't have a cat anymore !

 

Any ideas what the problem could be - far short of a dry joint somewhere, i'm fresh out of ideas !

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I had this when my alternator went where the warning lights didn't go off after the alternator was replaced, had the same warning lights.

 

After spending ages trying to figure out what the problem we started checking the fuses and one had blown, replaced that and everything was fine. I can't remember which fuse it was though but might be worth having a quick check of them, it was one of the small fuses.

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Thanks chaps, I'll have a go with the fuses tonight.

 

I've not had the dash trims out for a while, but, because the warning lights are either side, it would be odd for both plugs to not be in correctly - or have a dry joint somewhere?

 

Odd that it was fine before I tidied the engine bay up, then after refitting everything, my alternator packed up. Replaced it with a new one only a few weeks ago, and all seemed fine. Then randomly these lights started flicking on and off, with my voltage gauge flicking between 12.9 and 15.7 with the engine running, so I limped it home, replaced the alternator yet again, and although it now seems to be charging properly, the lights are now on permanently!

 

Bloody cars!

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It could be an earth fault. Are any of the lights dimmer than they should be? Check the earth strap under the intake manifold, I had the bolt come out of mine once and the car wouldn't start and those lights you mention lit up with varying brightness.

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Well, I've checked all fuses, and all look good. Checked the inlet manifold earth, and that's secure and tight, checked the battery to chassis earth, and that's also good?

 

Any other ideas folks, I'm worried about using the car in case something bad is going on !

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I had a dry solder joint on the right hand warning lights module. A quick go over with the soldering iron sorted the problem. Other than what else has been suggested, I'm not sure what else it could be mate.

 

Maybe try disconnecting the battery to reset the ECU, I have the Toyota manuals if you need to check anything.

Edited by markssupra (see edit history)
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Right, just been out for a drive, and something definitely isn't right.

 

On first start, it was sitting happily at 14.4v. Soon after leaving home, it dropped to around 14.1 - 14.2, headlights on and heaters on low. I was out for around 15 minutes, and pulled into a garage. Turned the heaters to max, and voltage steadily dropped from 14.1v down to 12.9v within a few seconds.

Flicked the heaters off, voltage climbed again.

Carried on driving, and a few minutes later, the voltage was up to 17v!

It hovered between 16v and 17v for a few seconds, then dropped back down to around 14v. Incidentally, at around 15v all the warning lights went out, then came back on either side of that voltage.

Got it home, was out for around 25 minutes in total, and once on my drive, Flicked the heaters back to max, and it steadily dropped to 12.3v before I switched the heaters back off.

Also, I noticed that if I put my foot down to accelerate, then voltage would also drop.

 

Does this sound like yet another faulty alternator, the wrong type of alternator, or is there anything else that could be causing this - to do with the car itself?

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I think you're right mark, odd that two new alternators are giving me the exact same issue?

I've compared my original alternator (oem) with one of the new ones this evening, and the old one is physically bigger, and has a slightly bigger pulley on it. I know the belt isn't slipping, and there is plenty of tension, but I'm wondering if I've been supplied two incorrect alternators?

Are the na ones different, apart from the amperage? Would an na one work on a tt?

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Thanks chaps

 

John, that would be excellent, if you don't mind? I'd be really grateful, even just to borrow to test.

Could I collect tonight, depending on where you live!?

Gary no problem - Chris has pm,d you with our phone number - we live near Romford

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Well, with a huge thanks to John Bailey, for lending me his spare oem alternator, the car now seems to work perfectly again :)

Straight away, all the warning lights went out, and power is stable, no matter how many electrical items I load it up with.

 

Managed to get my original alternator into a local specialist today, who diagnosed the fault. The internal connection for the voltage regulator had fallen off! 10 minutes, and £20 later, it's all fixed!

 

I'll swap John's alternator back for mine tomorrow morning, and hopefully this saga will be finished.

 

Also, proves the other two brand new alternators I bought, were at fault. You'd never believe it! I think the two new ones were 70A, as they are quite a bit smaller than my stock one. So, I guess they just aren't man enough. Hopefully this thread will help anyone else with a similar problem in the future.

 

Thanks to everyone for trying to help, and again, thanks John for lending me your spare unit :thumbs:

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Well, with a huge thanks to John Bailey, for lending me his spare oem alternator, the car now seems to work perfectly again :)

Straight away, all the warning lights went out, and power is stable, no matter how many electrical items I load it up with.

 

Managed to get my original alternator into a local specialist today, who diagnosed the fault. The internal connection for the voltage regulator had fallen off! 10 minutes, and £20 later, it's all

 

I'll swap John's alternator back for mine tomorrow morning, and hopefully this saga will be finished.

 

 

 

Also, proves the other two brand new alternators I bought, were at fault. You'd never believe it! I think the two new ones were 70A, as they are quite a bit smaller than my stock one. So, I guess they just aren't man enough. Hopefully this thread will help anyone else with a similar problem in the future.

 

Thanks to everyone for trying to help, and again, thanks John for lending me your spare unit :thumbs:

 

No problem Gary glad you got it fixed

See you at Bluewater next Friday

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Ok, scrap the above, it still doesn't work :(

 

I'd fully charged the battery, and after driving for 10 minutes, all the warning lights are back on, despite showing a reading of circa 14v. As soon as I load it up with heaters on full, the voltage drops, and continues slowly dropping, and when I turn them back off, it clubs back to around 14v.

 

I think the fully charged battery bought me false hopes, and took around 10 minutes to lose enough charge to trigger a fault.

That's now 4 alternators, two of which are brand new. It's definitely charging, but clearly the car is drawing too much power.

 

There must be something more sinister at play, but I'm buggered if I know what it is.

 

Is there anything that anyone can think of, it must be something so simple?

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Sorted, I think!

 

Poxy bad connection on the alt sensing wire, from the 3 pin plug - white wire.

 

Been messing around with it all morning, and it appears that it randomly loses contact, due to a dodgy pin.

 

I've ordered a brand new denso plug, sonim hoping a quick rewire will sort it out finally.

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Reading up about automotive alternators online there is mention of...

 

"Modern designs (since circa 1990) do away with the voltage regulator altogether; voltage regulation is now a function of the electronic control unit (ECU)."

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  • 5 years later...

Hi gaz, i know this is years old but i have the same issue. Same lights but no random drops in voltage to report. Instead when i give the car some welly and get full boost, i get the same warning lights! When running around on first turbo, no issues, turn off ignition and back on, no issues. Im wondering if its an earth now or possibly the same white cable??

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Hi gaz, i know this is years old but i have the same issue. Same lights but no random drops in voltage to report. Instead when i give the car some welly and get full boost, i get the same warning lights! When running around on first turbo, no issues, turn off ignition and back on, no issues. Im wondering if its an earth now or possibly the same white cable??
Hi mate, have you checked for ecu error codes?

 

Mine was simply a dodgy wire on the 3 pin plug, randomly making and breaking connection. Happy to report that I've not had any issues since fitting a new plug all those years ago.

 

 

 

 

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