Water temp guage with wierd readings on hilux

[BENOLUX]

Ok i have a 1983 hilux with a 2.4 diesel in it.
i wired up my water temp guage and now when i turn the lights on or off it spikes by about 30 degrees. (it is a digital water temp guage)
I have tried straight hard wiring to the battery to make sure it isnt wiring gremlins but it still spikes when accessories or lights go on.
does anyone have any ideas.

Cheers
Beno

[its aford not a nissan]

i would have thought at first that you have wired it to what you thought was an earth but is a dash light wire , but seeing as you wired it strait to the battery then the only thing i can think of is a bad earth between motor and body perhaps ?? , try hooking up a volt meter between the battery earth and where you earthed the guage and see if there is a volt reading

[BENOLUX]

thanks mate i will try that hey.
Maybe like you said the earth from motor is bad and causing it to vary. Im thinking about hooking it up to my dual battery which is earthed ealswhere on the car to see if it is the start battery/earth problem thanks again

[Kitika]

I had the same problem on my temp gauge and once I put an earth onto the body it was fixed. Dunno why it never had one to start off with tho.

[BENOLUX]

Yeh its odd, I was driving to work today and every time i accelerate it spikes from about 108 to about 116 then i slow down again and idle and it goes back down. I think it might be an alternator earth maybe ill have to check it out!!

[pongo]

i had a 22r in a 4runner that did the same. Turned otu to be a dodgy connector near the sender

[BENOLUX]

Thanks for the help all was a loose earth from engine to chassis sorted out or is much better now get temps below 100 which seem far more reasonable