Ls400 Temp Gauge Not Moving

[Mybikesacx500]

Hi all, Just got my magnificent LS400 5 days ago and absolutely love it, got LPG into the bargain, which it certainly was.

I have the usual collection of things to fix, with any just-aquired car, the one at the top of the list is my temp gauge.

It moves a millimeter or 2 when the ignition is turned on so doesn't appear to be physically stuck. It then just sits there, a bit below the begining of the markings. Everything else works fine, all is illuminated. I did notice that if I set the light dimmer, then turn on the lights, the panel illuminates on low for a few secs and then goes to fully lit. Seems ok after a run, presumably because something has warmed up?

I have had a hunt round the forums, and our American friends seem to have a lot more temp related problems, and it seems the thing to do is replace some caps and check for dry joints on the instrument cct. boards, which I can do.

I have ordered a CD from eBay, will this have enough cct diagrams to check the temp sender?

Any specific info on the temp gauge gratefully received

[Mybikesacx500]

Ah, got the lights sused now, when you dim the panel lights during the day, the light sensor says no, and turns them up again

Clever...

[steve2006]

Hi,

I think the temperature gauge issue is due to a faulty capacitor on the dash PCB but cannot locate the info, will have another look and post if I can find the info.

IT could also be the temp gauge sender unit try removing the wire to the sender and connecting it to earth and see if the gauge responds ( should go all the way to hot) if it does it will be the sender.

[michael Vercell]

Thank you for your post re non functioning temp gauge. I’ve never had any problems with my LS in 27 years of ownership. One month ago my first bulb went out , headlamp near side. So I purchased a new bulb and attempted to replace I had to disconnect the Battery and remove to fit the bulb. I did this though when we connected the Battery , light worked but temp gauge spiked to the maximum setting and doesn’t function. Can anyone help. 

[Malc1]

come come  1997 and 27 years makes 2024 ............. ain't quite there yet ............ sorry i have no idea on your problem .  I've sometimes had occasional electric stuff glitches but generally self-healed after a while 

Someone here might be able to help 

Steve 2006 above is a font of great knowledge

My headlamp bulbs too have often lasted decades .  great quality from new I know

Good luck

Malc

[BigBoomer]

You probably disturbed a wire that connects to the sensor for the temp gauge.
I don't know the LS400 but the sensor is normally bolted into the radiator and has 2 wires.

However, disconnecting the Battery waiting 15 secs, then reconnecting it can often resolve this kind of issue.

[steve2006]

The gauge sender unit is located left of the thermostat  housing under the ignition spark plug wire tray.

As the gauge is reading maximum/hot this suggests that the wire from the sender has been grounded so check for any pinched wiring around where you were working.