BigD

I searched but couldn't find exactly what I was looking for.

My 90 LS is running "hot." I noticed it after driving less than a 1/10th of a mile down the road after sitting outside in below freezing temperatures overnight. So it can't actually be overheating. The gauge sits at the 5/6 mark right after starting the car and when i shut it off it only drops to about the halfway mark.

So does this seem like a sensor or the actual gauge?

Also, the TRAC light is always on now.

PureDrifter

iTrader: (10)

did you check the coolant level? nothing frozen right...?

randal

Sounds kinda like a stuck gauge cuz I would think the needle should go all the way down when you shut her off. I also cannot see how the needle would get "stuck" if there were not some kind of physical trauma to the gauge. Can you tap on the front plastic and make it move at all when shut down?

NjRican

iTrader: (1)

Sounds like the needle is stuck. When you shut the far off all needles should drop to zero

BigD

Yeah, I checked coolant and everything is OK. Tried tapping on the gauge cluster but nothing happened. I think If the gauge is stuck it would not move at all but it moves freely b/w the halfway and Hot mark.

Also, TRAC light is off now. Must have been something else.

mOBSCENE

Did you ohm out the single wire temperature sending unit?

Piston1047

Man, I had this same issue. Mine would start in the middle during start-up and then would go up to hot after warming up. I even pulled to the side of the road thinking my car overheated. I replace the temp sensor with and it did not change. In the end I found another meter cluster from the junkyard and replaced the whole gauge board and it fixed the problem.

BigD

say again?

3UZFTE

Forgive me as it took 2 seconds to skim this, but here's what you should do. Check the basics, you could have air in the system, etc. But if the gauge moves within the first 30 seconds, theres no way, even with a head gasket failure, the temp would be 200*F. You probably have a sensor with an internal failure. But...

1. Check the basics, coolant level, crack bleeder coolant bleeder screw on top of thermostat housing, etc.

2. Test the sensor for resistance, being that you probably don't know the spec, if it's within them or not, you should just test for continuity i.e. a short to ground in the sensor. I have a faulty sensor on mine, and it's a short to ground in the sensor and pegs Hot, and falls as I hit the brakes, and raises as I hit the gas.

3. You could have a faulty cluster, but I doubt it.

K.I.S.S. Keep. It. Simple. Stupid.

zukikat

I have the opposite problem with a 1994 LS400 I bought a week ago.
The gauge cluster had the illumunation problems with being totally invisible at all times or strobing at random and the gas gauge that usually sat on the E peg when you could even see it but would occasionally twitch up to the actual correct level for moments at random.
One capacitor on one of the two gauge cluster boards fixed the illumination problems completely (and made the climate panel, stereo, shifter panel, and window switches light up instead of going totally dark at night too!) and two other capacitors on the other board fixed the gas gauge which now goes right up to the proper level with the key on from the E peg it sits on with the key off.

BUT the temperature gauge only goes up slightly above the C mark, about half way to the first mark above the C, nowhere near as high as I would expect it to sit at normal operating temperature, and where it sits with the key off is about that same distance down below the C mark.
I removed the two power/driver screws that connect the temp gauge to the circuit board and reinstalled/tighrened them while I was replacing the 3 capacitors to fix the illumination and gas gauge but the screws had no effect.

I drove the car nearly 200 miles to a mechanic friend at speeds in excess of 70mph in the rolling hills with no cooling or overheating problems at all and it never went any higher than just above the C mark near the bottom of the gauge.
He replaced the thermostat and flushed/converted the cooling system back from Prestone green type coolant to "Toyota Red" coolant and replaced the water pump along with the timing belt (among other things) as the car was at a timing belt interval and in need of some other tlc when I bought it last week, and yesterday I picked the car up from him and drove it the 200 miles home and the temp gauge still goes no higher than that same spot it went to when I first bought the car, nowhere near where I believe it should go at "normal" operating temps.

So my question is...
Is there something else that goes bad in the cluster like maybe more failed capacitors that will effect the temperature gauge? If I open the cluster and manually lift the needle to H and let it fall back to C will it maybe "re-calibrate" itself?
Is this a common problem, among the numerous other issues, with this gauge cluster?

Thanks in advance for the help!

Also note, this is my first LS and my first V8 but it's my 3rd Lexus and I've had at least one of each generation of Toyota Supra over the past 20+ years including 3 TT MkIV's and 4 Turbo MkIII's so I'm not an expert mechanic but I'm not afraid to dive in and the only real "suprise" I've run into with this very used 17 year old 180k mile '94 LS400 that I've owned for all of a week so far is a random tendency to rapidly hunt for rpms and flicker the check engine light while hunting and even stall at times (especially when turning) any of which can happen from any speed and any throttle level with no warning for no reason and it happens without throwing any error codes at all, which makes it very difficult to find but I'm confident I'll be able to track down and solve quickly through the help of this forum.

BigD

Pretty sure its the gauge now. I took another crack at pounding on the dash. Hit it a couple times and it moved the needle down to the 2/6 mark. Hit it one more time and it jolted it back up to 6/6 . Now i can't get it back below the 5/6 mark again.

It makes sense though since a few days ago i hit a monstrous pot hole where i thought i was going to need a new wheel afterwards. It probably shifted the needle up.

Oh well i guess i have to take apart the cluster.

MrFuel

iTrader: (3)

Ya, one time. I hit a big pothole and it broke my gas needle and once I replaced the gauge cluster with a good working one. It was fine afterwards.

zukikat

Oddly enough, yesterday my temp gauge climed exactly 1 mark's worth of distance higher yesterday as the car warmed up! The highest it's ever been since I've had the car, still plenty cold but better at least...
So I have a feeling it will eventually self-correct and go back to moving normally again over time, at least I hope so.

Bprakash

How did you eventually fix the guage?

Stereorob

id like to know about this one myself.. ive got a 95 but my temp guage barly gets above the first line or don't work at all. my car is 20 years old with mostly original parts and 193k miles so im scared my car is going to overheat and I wont know about it till its too late