New guy here and to Volvo
Had the water pump and timing belt changed. Shortly after the dash light for low antifreeze came on. It was a bit low and I topped to max line when cold. Light went out on dash. 100 miles later dash light came back on and engine temp stayed right at its normal temp. When cold I opened cap and started car to allow it to burp. A few bubbles but not much.
Light still on. I’ve replaced the bottle, green cap and sensor for bottle with new parts.
Fluid level appears to be staying the same. Just at seam on bottle than at max when warm. Light still on.
Any ideas on what could be wrong?

 

Either a bad sensor, a bad bottle, or the sensor is not pushed in all the way. (or the wiring from the sensor to the dash is damaged, rodents maybe )

The sensor is a magnetic reed switch, activated by a magnet built into the floating ring in the bottle.

 

Thanks hoonk.
I just checked under bootle and it’s dry by the sensor. It clicked when I installed. Also dry on line that goes to back of engine.
Unfortunately I agree that one or both of new parts could be bad. BUT before I order more parts I’d like to eliminate rodents or rubbing possibility’s.
Any ideas on a electric test at sensor plug in? There are only 2 connections in the plug. Any idea what readings would be at this plug? I’m assuming it would be hot all the time and magnetic float would complete the circuit when low.
Just guessing though.

 

Looking at the wiring diagram, pin number 1 is a brown/gray wire and pin 2 is a black wire. Pin 1 goes to the light on the instrument cluster, and Pin 2 is a ground coming from the instrument cluster,. Pin 1 will only have a ground signal on it (and hence illuminating the light), when the sensor in the coolant bottle closes and sends a ground signal.

SO......the way I would test with a multimeter is: First I would meter resistance between the pins on the coolant sensor in the bottle to see if they are shorted together. With the proper amount of liquid in the bottle they should read open or infinite resistance, and with little or no liquid they should read shorted or zero resistance. If that checks out ok, then meter out the wires at the connector. Pin 2 should read zero resistance between it and ground. Pin 1 should read infinite resistance between and ground.

I'm betting on a bad sensor in the coolant bottle (possibly intermittent) or an intermittent short to ground in the wiring between the sensor connector and the instrument panel.

Hope this helps.

 

Uff da electric isn’t my strong point but....
From the bottle readings on sensor using multimeter @ 20k. I emptied the bottle and pulled it out again and tipped upside down for full and right side up for empty.
Full level = unchanged or no reading.
Empty level = 0.00

On harness. Tested with black probe grounded on engine. Red into harness.

pin 1= 0.01-.02 Mines yellow wire.
pin 2= unchanged or no reading. Black wire.

Sooo I’m not sure at this point.

Psaboic any thoughts?

 

So - Resistance on the sensor with tank right side up and empty was 0, or a closed circuit. Resistance upside down simulating full was infinity or an open circuit. Sounds like the tank and sensor work. The bulb is grounded when coolant level is low.

Turn key on, unplug sensor, use a jumper wire to Ground the yellow wire or bridge the black and yellow wires for the sensor, warning light should come on, and go off when disconnected. The yellow wire goes directly to the bulb, black wire is connected to ground. In the diagram 7/73 is the level switch with a SB (black) wire on one side and a Y (yellow) wire on the other. Yellow wire can be found in plug A, terminal 14 on the back of the instrument cluster.

If your warning light stays on with sensor unplugged - it's not a bottle or sensor problem, the yellow wire could be grounded somewhere. 7/4 is the brake fluid level sensor if you were wondering.

 

Good morning guys. I mulled over how to post this and straight up with my tail between my legs.
A couple weeks ago I got this and loaded up a buddy for our first road trip. He was excited as he had Volvo’s in the past and chatted about how good the cars are and about how the safety measures had helped his wife thru 2 accidents.
when we hopped back in to come home a light was on the dash. He said it was the coolant light and well I didn’t know any different coming from Buick land. So we looked and decided to winged it home. The light would go out and back on a bit.
So without researching anymore I jumped into the coolant bottle and sensor and hoses and.....well it’s got some more new parts which doesn’t really bother me as it is a 98.
Thanks to the last post after relearning my multimeter and testing and removing bottle for the umpteenth time I made up a jumper for the sensor harness. Fearing the worst, trying to figure out where a rub or rodent had chewed thru, I jumped in and turned the key. Walla!!!! There’s a new light on the dash now. WTF now???? So I looked in the glove box and the previous owner did include the book. I hadn’t looked at it previously cause well I’m a guy.
It turned out the new light was the coolant light and the jumper worked. The original light was for a burnt out running light in the rear.
Learned Volvo has a light for burnt lights and they made it super simple to fix.
Lesson learned is again don’t listen to Matts advice.
Wherever in the world you guys are THANKS for your help.
Im sure I’ll be back with more Q’s but really thank you for your responses!

 

Laughing WITH you not at you as I read this......been there! Glad you figured it out!

 

When I replaced my water pump, I had the low coolant light come on. I found that putting coolant in the overflow tank was not sufficient to fully fill the system. I took off the top radiator hose and with a funnel, filled the radiator directly, and then filled the coolant overflow tank to the correct level. This took care of the problem totally.

 

Oh, car problems always give you so much trouble. Especially when you depend on the car, the fact that you detect some problems with it brings you down. In general, this does not seem to be a very serious problem. It's not the engine, so it's fine. I recommend that you turn to car service. It is nice if it uses software such as AutoLeap. It inspires me more confidence knowing that everything is organized and I will not be lied to. I also had a problem with the level of the antifreeze solution, and my husband, who is obsessed with cars, advised me first of all to empty the tank and, if nothing changes, to replace the part.