Speedo / ABS / Warning Light Problem?

I was wondering where a 1999 Volvo T4 gets the reading for the speedo? reason I ask is the speedo stopped working yesterday for about 5mins and the ABS light as well as the red exclamation mark came on at the same time. This also happened again today for about 2mins. Is this a common problem? I'm guessing it would be an earth fault but where? Would a duff battery be likely to cause it??

From my experiences with the 480 a duff battery can do all kinds of crazy things. My mate managed to damage his NS front ABS sensor after hitting a stone in his 2.0L S40. The speedo stopped working and threw up the ABS light.

Replaced the battery but no joy Any more suggestions? It is an intermittent fault..

Loom under the rad perhaps? this is a known issue with the 40's....might be worth checking it out as it wears through.

will have a look on the weekend when it's on the ramps. Could be as a result of the snow/grit I suppose casuing a bad earth

Where are the earthing points for these? Do they share the same point? Anyone have an electrical wiring diagram?

bump for today...

I have a feeling this fault is due to me removing and replacing the battery several times in the last week as this is when the problem first arose. Can anyone confirm what the the two wires that attach to the positive terminal of the battery are for? I am guessing the thicker one is for the starter motor and the smaller one is for the ECU and everything else? If so the smaller one seems to have frayed slightly so I'm guessng this may be the cause of it as it may cause an intermittent voltage drop or something....?

Cleaned up terminals and body earth point but no joy. The problem seems to occur when I start the car up... I think something's shorting or dodgy connection somewhere? Please help as this is the last problem and has only started since I removed the battery