C70 Warning Lights - Fault?
 

I have a 2005 C70 - Every few weeks I have 'Brake Failure'; ABS, Engine, Power Steering & Transmission service lights come on & I lose power, all dials on dash stop working. As soon as I turn the engine off, the immobiliser comes on.
The next day - the cars is fine again. There is nothing wrong with the brakes etc!
Does anyone have any ideas please? We think it may be the sensors. Can I disable them?

Limp mode
 

You need to get the codes read to find out what's wrong. Disabling the warning lights is an MoT fail,

As Clogs said.
Disabling warning lights defeats the object of them...also, what sensors would you disable if you don't know which may be causing the problem...it could be none of them but a loose connection somewhere...
A basic code reader should highlight any faults but it may need more specialised Volvo diagnostics

Possibly could be the electrical part of the ignition switch.

While the engine is running try gently moving the key in the ignition one way then the other to see if it creates/solves issues.

Also check the connections on the battery, particularly the secondary positive connector (has a group of smaller wires joined together that go from the battery connector to the fuse box near the cabin filter).

Check the earth points as well, particularly the main one in front of the battery.

Given that when this happens you state that ALL the dials on the dash stop working, I doubt this is a fault caused by one or more sensors, it sounds like a more basic electrical fault to me. So although normally I'd say yes, definitely read the codes, in fact in this case I think Acshortt5 above is spot on IMHO, the electrical part of the ignition switch in particular is a common fault on these.

+1 on ashcrofts thoughts - electrical part of ignition switch. Post back and let us know what you find.

My Car
 

Hiya
I have a MY 2006 C70 & had similar issue, various warnings & going in to limp mode, turned out the connections on the CEM needed a clean. Been all ok since. On the Mk2, the CEM is located below the glove box, behind the carpet. Can't say if Mk1's in same place but I'm sure someone will know.
Fred :regular_smile:

When we had the codes read it said everything was wrong with it!

Thanks for this, will give it a look

Just to be clear your C70 has a soft top roof?

If it's the folding hardtop then that is a completely different car and you need to be asking in a different part of the forum.