PDA

View Full Version : Dash warning lights



wolverene
11-04-2005, 12:35 AM
Hope someone can help out here. I`ve got a 1990 GT-R and three of the warning lights keep coming on when the engine is running. These are the Battery symbol, the rear light one and the oil sign, when these come up the voltage meter drops a little bit. I don`t know if there is a connection but sometimes the speedo cuts out and the needle drops to zero then back up to speed. Anybody got any ideas? So much easier sorting out mechanics than electrics!
Cheers
Keith :

waytooslow
11-04-2005, 05:11 AM
Sounds like you got some pretty bad electrical problems to me. Almost like you have AC voltage ripple piggybacking onto the dc...check your alternator. And grounds. Just my guess.

AllOutRed90
11-04-2005, 05:42 AM
Be sure to check your oil level, and battery. lol...

waytooslow
11-04-2005, 06:11 AM
No, seriously. We had a vehicle in the shop with this problem. Think it was an Explorer. All sorts of unrelated electrical faults, even when we component checked, they still threw codes. Turns out the alternator regulator had fried, and the AC voltage generated by the alternator in it's native state was leaking by and getting onto the DC circuit..This plays all kinds of hell with the sensors for say, ABS/speed, (on our unit, the speedo kept reading 10MPH at standstill, even though the computer reported 0MPH to the scan tool) oil senders, etc. I have the waveforms saved, as soon as I export them, I'll upload em so you can see what I'm talking about.

91celicagts
11-04-2005, 06:52 AM
welcome to ownership of celicas.

waytooslow
11-04-2005, 05:20 PM
Can't find the waveforms, but theres a quick test you can do. Turn headlights on bright, and windshield wipers on, blower on high, etc. to get maximum load. If you have a nice system, turn it up! Now, take a multimeter, put red on the main alternator output (big wire) and the other on a known good ground. Set your meter for AC, and check for any voltage. Anything .3 or higher is suspicious, .5 or higher is bad.

wolverene
11-04-2005, 09:13 PM
thanks for the answers guys. when you say put lights and as much else on that I can I guess you mean with the engine running and by the big wire do you mean the one on top of the alternator -not one of the three pin plug wires coming out the side? sorry if I sound thick but I dont trust anything I cant see-electricity! dont want to blow anything up.
cheers

waytooslow
11-05-2005, 02:28 AM
The engine needs to be running, and you need to draw as much power as possible to strain the alternator system. Hit the cigarette lighter, turn your brights on, radio, defroster, fan on high, etc. Use as much power as possible.. I do mean the big wire of top of the alternator. Just put your red lead on that,(make sure you have good contact) then take your black lead, and put it on a body ground. Make sure theres no paint in the way. Scratch off a bit if you have to. Set your multimeter to AC (1 volt) and look for any voltage. If it reads .3 or higher, take it to autozone or something and have em test it further. If it's .5 or higher, its more than likely toast. The numbers can be negative (-.3 -.5), that means you have the leads mixed up, which don't really matter.

opnwhlmnd
11-05-2005, 10:34 AM
If your having the three lights that you described come on at the same time, it's 99% of the time your alternator. Toyota ties the three lights to a diode inside the alternator. They have done this on all of their vehicles for years. It's Toyota's way of telling you that your charging system is weak.

Your speedometer has no effect on this problem. The speedometer is cable driven on your model. The Explorer the other poster was describing, has an electronical controlled speedometer.

wolverene
11-05-2005, 09:14 PM
beginning to see the light! will get the hood open and do as very clearly suggested- one thing I would query is that my car is an auto g/box and the speedo is electrically driven, no cable unfortunately as that would be an easier fix. Once again thanks to you guys for the help- I`ll keep you posted but it sounds like you have all had experience with the problems.
cheers
Keith :bigthumbu

waytooslow
11-05-2005, 09:30 PM
I'm sure that the speedo problem is related, as per my previous posts. I don't know what that kid was talkin about...
Wolv, you learn REALLY fast that electrical problems are often interrelated, and often a pain in the ass to diagnose. Logical, methodical checking is the way to do it. Start big (alternator, battery, main harnesses) and work your way down to the small(grounds, connectors, components, subharnesses). The big stuff is easy to get to and test, so it will save you time in the long run.

Luni
11-06-2005, 09:29 AM
Those lights on signify there is a fault in the charging system.

The speedometer isnt related as it is cable driven that year, not electrically driven.

Punisher
11-06-2005, 10:52 AM
Also, you can tell that you are gettin AC voltage if your headlights flicker..

Had that shit on my moms and brothers accord.. Lights goin crazy.. all kinds of crazy ass shit... that was the end of the alternator.

CelicaNR
11-06-2005, 11:00 AM
Alternator. I had the same problem. Was exchanging battery and all different things, at the end it was just that stupid alternator.

wolverene
11-06-2005, 12:40 PM
Hey Luni, I`ve checked the speedo drive from g/box and it is an electronic drive -If it should be a cable someones nicked it! Found this out when I first got the car as speed reading was jamming at 40mph- took the instrument cluster apart and the printed instrument panel had lifted and was jamming the speedo needle, just reglued the sheet back down and it was fine, but I had spent 2 hours under the car trying to trace a cable before taking the speedo cluster out and finding that no cable came up to connect to it. So def. electric sender on g/box,

Luni
11-07-2005, 06:42 AM
Hmm. Oh. Youre not in north america are you?

I was assuming anyway. I figured since MR2s didnt get an electrically driven speedo cable till 93, the celicas didnt either.

waytooslow
11-07-2005, 07:23 AM
Nope. The auto tranny's at least, are electronically driven.

Luni
11-07-2005, 03:20 PM
Well another assumption on my part.

acidice333
11-11-2005, 12:47 AM
I tried your test just now.. I got 30.x with everything on (radiio, high beams, fan on high except for dash ligihting... with highbeams off I got 31.x .. I set my multimeter on 200AC since thats the lowest dial its got. Negative lead to battery negative post, postive lead to that big wire that is nut'd down on the alternator. I was amazed when I disconnected my alternator, my remote starter worked. Does that mean my alternator is toast?


The engine needs to be running, and you need to draw as much power as possible to strain the alternator system. Hit the cigarette lighter, turn your brights on, radio, defroster, fan on high, etc. Use as much power as possible.. I do mean the big wire of top of the alternator. Just put your red lead on that,(make sure you have good contact) then take your black lead, and put it on a body ground. Make sure theres no paint in the way. Scratch off a bit if you have to. Set your multimeter to AC (1 volt) and look for any voltage. If it reads .3 or higher, take it to autozone or something and have em test it further. If it's .5 or higher, its more than likely toast. The numbers can be negative (-.3 -.5), that means you have the leads mixed up, which don't really matter.

alltracman78
11-11-2005, 12:59 AM
Hey Luni, I`ve checked the speedo drive from g/box and it is an electronic drive

GT-R isn't a NA model.
As far as I know, only NA models got a mech speedo.
All others were electrical.
Dunno why?

Luni, 93s had a mech too.
Celicas didn't get electrical until 94 in NA.