WTF! Coolant Temp Issue

[Ed Doe]

Righto,

With extensive help from Niall & Sam on saturday, the hub finally got changed on my '6, along with the loom AGAIN! After som teething issues which ended up as an earth point not mounted, the car fired up and runs fine. HOWEVER....

There is still this temperature issue...

I wont bore you with all the details as I'm sure most will gouge their eyes out at having to read another thread about me moaning about my car.... but I noticed something when I got to work today... took a video of it (link below)

https://dl.dropbox.com/u/91691146/2013-0....54.27.mp4

So when I turn the lights on, the engine runs hotter....

Now, one of my sidelight bulbs is out (n/s headlight), I don't know exactly when this happened, but I took the bulb out when I was stuck at the side of the road last week waiting for the AA man. Is it back-feeding something to do with the temp sensor?

Any ideas anyone? I think I'll just drive home with my lights off tonight as it makes me feel better with the temperature at 90ish rather than 100 LOL!

[C.A.R.]

Need to trace the circuit back from the sensor to the dash and check for continuity. Certainly an odd one...

[Ed Doe]

It periodically does the same thing but related to throttle position too... As in off the title it sits at 90,on throttle it immediately jumps to 110, coming off throttle it goes right back to 90... It's weird!

[samass]

Sensor/wiring/earths, one of them

[C.A.R.]

Multimeter time!

[Kimmie]

Just give it back to Scott already, she doesn't play up with him!

[Ed Doe]

Surely it can't be the wiring on 2 different looms though!?!
I'll replace the sensor when I get a minute this week, and see if that sorts it. I was considering boiling a kettle, plugging the sensor spare sensor from your car into the loom, and then dunking it in a cup of water to see if it replicates the issue above...

I may be wrong but in my head I'm definitely swinging in favour of earth points if other electrics in the car (the lights, and the throttle - tps or map?) are interacting with the temperature...?

[cully]

1 st check the earths

2nd your alternator may be fubared so check the running voltage you might find the voltage creeps up under load meaning the reg pack in the alternator is playing silly

[Ed Doe]

You know I wouldn't be surprised if the alternator is buggered actually come to think of it...

Complete newb at electrica; how do I check the alternator running voltage?

[Parksy87]

Multimeter on the battery, should read 14.4 volts or there about

[cully]

volt meter across the battery not running will measure the battery voltage (about 12-13v)
volt meter across the battery car running will measure the charging voltage (about 14.1V)
voltmeter across the battery car running with lots of electrical load (lights heater fan demists) (about 14.1v) should not varry with engine speed

anything over 13.8v will be able to charge a lead acid battery

[Ed Doe]

Solved! Gearbox earth was chronically loose! Tightened up and it cranks as it should and the temp is back to normal!! Hooray!