Stange Fuel, temp and oil temp reading with headlights on

[ollster 0]

Putting lots of electrical load on seems to make my fuel and temp guage rise and also give me higher oil temp reading on the MFA. I have checked all the earths that i can find and this problems is the same with the engine off but just the ignition on so im guessing its not the alternator reg problem. Can anyone shed some light on this? by the way the speedo and rev counter are not affected by this

[ben16v 0]

how much difference mate?

 

think thats ok if its only a couple of degree`s, although dunno about it doing it with the ign off

 

ben

[Shilakadaddy 0]

I noticed this on mine a while ago... turning the lights on made the oil temp go up by 10 degrees! I just figured it was due to having 10 year old electrics :)

[ollster 0]

it doesnt go up loads, but if i sit and switch the lights on and off a few times it will make the fuel guage jump up in steps. I was wondering if it was a faulty voltage reg on the back of the lcoks or an earth?

[LowG 0]

It's likley to be an earth problem, I have seen it on several corrados, on some the oil temp with lights on jups as much as 30C +.

[ollster 0]

yeh it sounds earth related to me too, so whats the best way to a) test if its an earth problem and b) rectify it, all of the engine bay earths seems fine so is there another earth behind the instruments?

[RW1 0]

another earth behind the instruments?

 

Should be, one up in the dash at the bonnet pull. And another maybe further forward.

 

Whats the voltage reading between the alternator body earth and the battery earth pole with the engine idling. Needs to be done with a DVM.

 

.

[ollster 0]

which is the alternator earth, i thought it just had positive and then the blue wire which fed the battery light on the dash?

[RW1 0]

The metal outer body of the unit will do fine.

 

.

[ollster 0]

Right with the car up to tempreture the alternator reads 13.82v at idle with no electrical load on; with nearly full electrical load at idle it reads 12.25v. This reading was taken by connecting the pred probe on the multimeter to the alternator red wire and the black probe to the negative on the battery.

 

There is pretty much a 10 deg difference on the mfa oil temps with electrical load on such as light, and im not sure how its affecting the fuel or temp gauge

[ollster 0]

^^^^^^^^^^ does any one know if this is correct or not?^^^^^^^^^^^^^