Thermotime Switch / Temp Sender... CSV ???

[randall977]

I have a cold start problem - I'm so close to the solution that it's very frustrating.

The cold start valve doesn't fire but the valve itself is fine. The problem is that the CSV is recieving only a 4.5V supply from the thermotime switch; it should be getting 12V. I tried another thermotime switch from my other Audi and it produces exactly the same 4.5V supply - so does this mean they both have identical faults? Unlikely. I then read on a forum that the thermotime switch is earthed via the temp sender (I believe this is the sensor next to the thermotime switch which I assume tells the thermotime to either work or not work?). So anyhow, it's a K-Jetronic system (pre ECU), 2144cc WC engine.

Why 4.5V and why does the Haynes manual not show the temp sender as being part of the curcuit. I'm told 4.5V is the ECU supply voltage - there's no ECU but there is a impedance converter and Hall TCI control unit - but these aren't anything to do with the CSV are they? Anyone had this kind of problem, know anything about the temp sender???

Thanks in advance

[Drazic]

Hi Randall.

I'm rather unamusingly having a similar problem with my 90Q at the moment. It's been suggested that it may be my dizzy, specifically the rotor arm. I'm gonna replace mine ASAP - will let you know how I get on.

Cheers

[randall977]

It sounds too easy - I do actually have a new rotor arm lying around- but why would this cause 4.5V at the CSV? You can test the rotor arm (this is my excuse to show off my workshp manual!).

Audi100EngineManual130.jpg