Calling all you electrical gurus....!!!

[andy-w]

Hello Guys....brought the chim into work today as i am taking it for the mot when i finish.

Its about 7 miles to where i work and the car drove brilliantly...pulled really well through all the gears, was very smooth and i never noticed all the joins in the road that used to make it rattle and sound like a bag of nails.

I do however have one slight problem.
All the dials were working fine on the way in oil pressure was hovering around the 50 mark and was on 30 at tickover, temp gauge went up to 60 deg which i would expect on a cold morning like today.
The i pulled into the company car park and the oil, temp and fuel gauge are all at 0...!!!

I can only assume they have a common earth and that has become dislodged???

The car still runs really well so it is not a major urgent job but it would be nice to know what it is doing!!!

[over_the_hill]

or they might all be on the same fuse.

[Pink_Floyd]

All of the gauges on the dash have a common earth, so all would stop wonking. The gauges you say have stopped have a stabilised supply so that the supply voltage is constant. It could be this module that is no longer working.
If you did not have a stabilised supply then as you rev the engine the gauge reading would change. As the engine is revved the output voltage from the alternator varies from 12.5 to 14 Volts. The stabilised supply regulates the supply to something like 10 volts no matter what the alternator is producing.

[andy-w]

Pink_Floyd said:

All of the gauges on the dash have a common earth, so all would stop wonking. The gauges you say have stopped have a stabilised supply so that the supply voltage is constant. It could be this module that is no longer working.
If you did not have a stabilised supply then as you rev the engine the gauge reading would change. As the engine is revved the output voltage from the alternator varies from 12.5 to 14 Volts. The stabilised supply regulates the supply to something like 10 volts no matter what the alternator is producing.

The oil pressure and fuel gauge readings were constant when the engine was revved, well the oil pressure one moved slightly as expected but the petrol and water temp were both constant.

Cant remember if the rev counter was working so i shall have to go out and check at dinner time to see what is happening...

I shall also check the fuses again....great job that is!!!

[Cider Andy]

Pink_Floyd said:

The gauges you say have stopped have a stabilised supply so that the supply voltage is constant.

I didn't think they had. They're all electronic and I thought each gauge stabilised its own supply? Or maybe this is something that changed over the years?

Anyway, they all come off the same 12V feed as well as having a common ground so the problem's likely to be simple, like a fuse or a bad connection. But it might involve removing the dash top to find it.

[spend]

Was the speedo & heater blower working? they use the same common fuse on the dash? (heater uses a different ground tho)

Dave

[andy-w]

spend said:

Was the speedo & heater blower working? they use the same common fuse on the dash? (heater uses a different ground tho)

Dave

Yes the heater was blowing but i had stopped moving when i noticed the other gauges were not working...it was raing at dinner time so i did not go for a look...i shall do it in the garage when i get in...

Luckily i have not fastned the dash top on yet for this very reason

[spend]

It prob is the earth then, pretty sure that bunch go under the radio. IIRC mine went down to the chassis or near the steering column?? I 'redesigned' my grounds so a bit sketchy sorry.

I was very happy using a short battery cable across the 2 chassis mounts by the transmission (so effectively the battery connects to 2 chassis points) and then a nice fat cable to an accessible stud under the dash to link all the wiring to. Just mentioning it as I know you are re-trimming and I really think it is worth duplexing those inaccessible grounds like that one and the one under the rads.

Dave

[andy-w]

spend said:

It prob is the earth then, pretty sure that bunch go under the radio. IIRC mine went down to the chassis or near the steering column?? I 'redesigned' my grounds so a bit sketchy sorry.

I was very happy using a short battery cable across the 2 chassis mounts by the transmission (so effectively the battery connects to 2 chassis points) and then a nice fat cable to an accessible stud under the dash to link all the wiring to. Just mentioning it as I know you are re-trimming and I really think it is worth duplexing those inaccessible grounds like that one and the one under the rads.

Dave

I have doubled up on the front earth point and the rear one as well behind the petrol tank...think i might do that on the two above the transmission...like you say they are close together so it will be easy enough...
I am pretty sure too that they go down to the left hand transmission mounting point.

Just to check i have grasped what you aer saying - once i have double up those earth points run a cable up under the dash, 8mm (ish) bolt and then earth things to that???

[spend]

Exactly Andy.. IIRC the battery goes to the LHS chassis bolt and a load of earths to the RHS one, just pull them out and link to the new stud you create. It just makes things easier to maintain & test, its a nightmare getting to those main ones Make sure they are well cleaned up and leccy greased then you should be good for years

Dave

[andy-w]

Cheers spend...i think i shall do that as a matter of course anyway...sounds like a better way of getting a decent earth...i shall let you know how i get on tomorrow...

Cheers guys

[andy-w]

well i have lost windscreen wipers, heater, all dash instruments including speedo and rev counter (but not the clock!!!) and indicators...going to go and check the fuses now!!!

[spend]

Its the +ve ign feed then , clock is different +ve same -ve, heater is same +ve different -ve (normally - DYJLE )

BTW you need that feed to start the alternator charging - without it you are running the battery flat when driving!

Dave

Edited by spend on Tuesday 8th January 17:33

[andy-w]

I hate electrics...with a vengeance...!!!

I am sure to design a car wiring loom you need to be either on drugs or drunk....or both!!!

[andy-w]

right - as spend said it was the main ignition feed...10amp fuse had well and truly melted.

I now have a second problem...while i was pulling the rest of the fuses to make sure no others had blown i tripped the imobilizer...i have tried to turn it off but for some reason it just doesnt want to know....!

i think it is time to strip out the old imobilzer and get a new one, especially as i only have the one fob and it is very old, has anyone done this before and what do i have to take out...please do not post on here!!!

[spend]

andy-w said:

I hate electrics...with a vengeance...!!!

I am sure to design a car wiring loom you need to be either on drugs or drunk....or both!!!

I've stopped taking drugs, cheeky tw@t

Dave

well for the paranoia anyway

[andy-w]

spend said:

andy-w said:

I hate electrics...with a vengeance...!!!

I am sure to design a car wiring loom you need to be either on drugs or drunk....or both!!!

I've stopped taking drugs, cheeky tw@t

Dave

well for the paranoia anyway

I have had to give up for the night...can i hell get the imobilizer to turn off!!!

bl**dy electrics!!!!

[That Daddy]

Andy YHM

[spend]

Its a lot easier to find problems when you have working courtesy lights , isn't it?

Dave

[andy-w]

spend said:

Its a lot easier to find problems when you have working courtesy lights , isn't it?

Dave

but when you dont and it is dark you can see all the little sparks from the fuse box when you give the wires a wobble!!!!

Cheers for the info Simon and Dave, much appreciated and a job for the weekend methinks!!!