Electrics issue.....fuses?

[paulhannon]

So this is probably a weird one:

I have a V35 (350GT) 2005 - one of the dashboard back-lights, behind the odometer has died or has dimmed, the back-light for the dashboard clock only reliably works/comes on when the headlight sensors determine it's nighttime outside and dim the dashboard/gauge lights, my passenger side interior light only comes on sometimes when I open the doors AND the bloody fuel gauge doesn't work properly (sometimes it reads it's half-full and then suddenly as I drive it points to being full. Ohhhh and my vents will sometimes blow warm air, even when set to the lowest temp - other days it will be fine. (not because of the engine being warm or cold or it being a hot day etc)

Now I'm completely uninformed about the intricacies of cars, but i feel some, if not all, of these issues are connected because; as I drive to work, sometimes in the cold/damp mornings, my clock will be lit up and working and so will the fuel gauge. But a few hours later when I go to get food, back to square one! 

So I come here to ask for advice - I don't think it's a the actual fuel gauge itself because of how it all seems to happen together. Drawing on my radio technician background, it all feels like something to do with fuses or earthing issues, but I wanted to see what you guys think first.

Thanks

[GTSBoy]

Give all the likely fuses a wiggle. Pull 'em out put 'em back in. I have one circuit on my car (that powers the radio etc) that needs this every couple of years.

But I would warrant that it's more likely an earth problem.

[paulhannon]

42 minutes ago, GTSBoy said:

Give all the likely fuses a wiggle. Pull 'em out put 'em back in. I have one circuit on my car (that powers the radio etc) that needs this every couple of years.

But I would warrant that it's more likely an earth problem.

Thanks so much for the reply. Can I ask, is there a particular place I look at to address an earth issue? 

[GTSBoy]

Sadly, it would probably be behind/under the dash. You need to look at the wiring diagrams to see where there are earth points "close" to the instrument cluster and other devices in that area. Then you can pursue the wiring from those things back towards the various earth points on the steelwork behind/under the dash area.

Keep in mind that sometimes the earths are not actually where you might expect, and might, for example, be out near the sensing devices (like maybe the fuel sender). It is more likely that you will have dud earths out in the open/wet areas of the car or where f**kfisted previous owners could have done something stupid than behind the dash. But you can't exclude the possibility that someone has damaged something behind the dash either.

Edited June 4, 2019 by GTSBoy

[paulhannon]

Alright awesome, this gives me a lead to follow. Thank you again.

[niZmO_Man]

Yep, get under/behind the dash and start poking around. Have fun!
Reminds me of my R32 clock, it used to turn on for a few minutes every few months, then once a year. Now it has left me completely