In article <email@example.com>,
> Hello again,
> been a while since my last posting but have been keeping up with
> everything (pretty much anyway).
> I've got a issue with my 1990 740's speedo. When traveling along at any
> speed over any surface it will just drop to zero. A well placed tap on
> the top of the dash brings the speedo back to life.
> Some days it won't do it at all, others it won't work for miles and then
> bring itself back to life. I've had a feel around behind the speed (it's
> quite easy to access from underneath the dash) and can't feel anything
> that's come loose at all so I'm guessing that it's a dry joint somewhere.
> Any suggestions as to what I should do? If possible, I'd like to avoid
> taking the dash apart but if needs must then so be it.
> Thanks and regards,
More often than not the speedo is losing signal from the sensor in the
diff. The wiring is not very stout and tends to break inside the
insulation, due to excessive clamp force on the wire when the waterproof
sleeves were molded over the connector.
Before you remove the wire seal on the sensor pull on the wires and see
if they stretch easily. If they do you will have to replace the two
wires in the connector with Volvo p/n 3523813. These are the wires for
converting the early style 240 washer pump harness to the later
connector on the pump motor. The wires in the harness are a twisted pair
so take care to maintain the twist when splicing in the new wires.
The goal when driving is to miss the maximum number of objects.