Electrics: 70: Low coolant warning light problem

[wickey]

I have a problem with my '00 v70xc (1. gen). Low level warning light is randomly on and off. Of course, there is plenty of coolant in expansion tank. However, after changing the sensor for new oem one, the problem stays...

Is there some known issue with cables, or should I expect long hours trying to find the bug in connecting cables? Any comment is highly appreciated.

[DSK]

This should be triggered by the sensor and the sensors are robust. As you have changed the sensor and its not fixed the issue, it means more investigation.

When does the light come on, e.g when parked, when driving, conerning etc?

Have you managed to stop and check the coolant level when you see the light?

Also, without meaning to sound like trying to teach you to suck egss, when you say there is enough coolan't in the tank, is it at the min or maximum marker?

[Cookeh]

When you changed the sensor did you clean up the contacts on the harness side? Sometimes the cables around the coolant hoses and tank become slightly oxidised or coated in coolant from small little drips or leaks. Beyond that I'm afraid it might well come down to spending hours tracing wires.

[wickey]

The issue is, that comes on and off quite randomly. Without any noticeable connection with cold/hot engine, driving hard, idling etc. I have checked the level when it on is and there is enough coolant - at least in the middle of scale, closer to max. As far as I know, the light should go on only when below min.

[wickey]

Originally Posted by Cookeh

When you changed the sensor did you clean up the contacts on the harness side? Sometimes the cables around the coolant hoses and tank become slightly oxidised or coated in coolant from small little drips or leaks. Beyond that I'm afraid it might well come down to spending hours tracing wires.

I will try to do that. I am not quite in the mood of tracing the fault along the cables which module is responsible for low coolant level? I am thinking of pulling it out and checking for cold spots in soldering (as I am used to do with abs module on each and every one 850/70 through the years..)

[wickey]

Oh and there are no issues in this area according to vida scan..

[Stumo]

Make sure the float inside the expansion tank is free and able to float up and down. A bit of grit in the tank can cause it to bind up, and it gets stuck when the level sloshes about.
Cure is to take tank off and clean it out and check float(magnet) can slide fully and not get caught, or replace the tank and get a nice new white shiny one.

[Stumo]

The sensor that clips in is a reed switch ( contacts opened and closed magnetically). The sensor shaft goes up inside a pocket in the plastic and a circular magnet float moves up and down the shaft depending on level. Usually the reed switch is pretty robust. You can check it’s operation by removing it from the tank and moving a magnet up and down it’s length while a helper watches the light.

[wickey]

most of the components for cooling system are renewed recently (20k km) - radiator, hoses, thermostat, expansion tank.