OK chaps,
My brother's been fitting a CD player to the ex-vario, to get some reasonable sound quality there are some rear speakers involved. However, now I've lost the fuel gauge, rev counter, ambient temp gauge and coolant temp gauge.
The radio/CD works fine and all 4 speakers are ok too. All fuses are fine but the wiring's very confusing and haynes is zero help. The dash illumination fuse (no.5) blew twice but has been fine since.
Anyone know what links all the knacked items? Clearly either power to the gauges, or common earth.

Help me I'm stumped!

I had much the same problem a few years back when I tried to use the existing wiring to wire up an aftermarket CD player to my 740 (Why I just didn't use a wiring loom adaptor still escapes me)

Turns out it wasn't earthing properly causing those little problems. I ended up running a separate earth/live off the ignition and putting in-line fuses in. It was a terrible hash-up as I recall, but got the job done!

I fear I may haveto do the same here.
Forgot to add last night, a multimeter confirms there's a resistance value for the fuel sender, and the correct rpm signal too. So the problem seems to lie with the instruments' power or earth supply, but not on the gauge cluster itself.

you havent managed to pull a cable out from behind the dash have you?

mines done this - there is a red (on mine anyway) wire that splits feeding power to the radio and the dash. i'd cut it for some reason and then resoldered it badly and the dash lighting, tacho, fuel / temp gauges failed when going over bumps and the like.

the multiplugs had a thick red going in then a thinner one coming back out the same socket and off up into the gubbins behind the dials. see if this has been cut as it appears to be pointless at a glance.

hope this helps

toby

electrics failing after installing a radio in a 300 series car is a well known problem:D with an easy fix,

for some stupid reason volvo desided to split 3 wires and put a connector on these wires. when one of the 3 or more wires are disconnected from eachother, the rest of the dash won't get the electrical current.

so, behind your radio.reconnect the 2 green, 2 brown and 2 red/black wires to eachother, and then connect the radio to these wires and problems are solved and you have a working radio!

Yup exactly whats Volvodspec said.

Cheers lads, I shall give that a try tomorrow and report back. I do remember being puzzled by the mulitple redundant wires arranged in pairs. I drove all the way to Pete Farrell's and back today with no fuel gauge!

Teah, you've lost a switched live connection somewhere. That's the red/black striped wire. As the other's say it connects through the radio terminals on the later cars. The reason only half the dash doesn't work is because the other half gets its live through another wire. You'll be able to get some warning lights like the rear window heater and rear fogs, but the main ignition warning lights etc along with all the gauges won't be working.

pettaw wrote:Teah, you've lost a switched live connection somewhere. That's the red/black striped wire. As the other's say it connects through the radio terminals on the later cars. The reason only half the dash doesn't work is because the other half gets its live through another wire. You'll be able to get some warning lights like the rear window heater and rear fogs, but the main ignition warning lights etc along with all the gauges won't be working.

the red-black wire is a feed switched by ignition, green is a direct battery feed, and brown is the ground. even if 1 of the ground wires is loose, half the dash won't work, or you'll get all kind of crazy things.