Fails to start during hot weather

[baz1701]

Having an issue with my wifes 1.4 2001 meridian.

When the weather is hot the central locking packs up as does the clock and the engine turns over but does not start.

I have already tried a new ECU and Cabin control module and instrument panel (speedo, rev counter etc) without joy.

I have plugged a diagnostic tool in and just gives one error code P0115 Engine Coolant Temperature Circuit Malfunction.

Open the doors and windows and generally between 10 to 20 miuntes the fault clears itself and the car works fine. My next step is to replace the dash

[Jimbo]

Have you not thought to change the coolant temp sensor

[baz1701]

Have you not thought to change the coolant temp sensor

Changed the sensor as well. The cooling fans packed on low speed so the sensor was the first thing I changed. This problem was present before and after the sensor was replaced.

Looking at the CCT diagram in the haynes manaul most of the effected systems run through the cabin control unit, but this was changed for a second hand module. I know that module might also be faulty but not with the exact same fault.

[Toms306]

At a guess, I'd say theres a high resistance fault 'somewhere' in the wiring which could be a pain to find. The ambient heat increases the resistance even more so the parts stop working altogether at that point.

Is the battery good? Assuming it is, is there a good earth between the battery and gearbox, and one to the chassis? You'll need a multimeter to check. Then you can start checking earths inside...