Sensor problems on a 2001 Volvo V70

Maintenance/Repairs
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1

Dear all,

I have some problems with my 2001 Volvo V70 about its light sensors and tailgate sensor.

Starting from this spring, every time when I turned the right-turn signal light on, the bulb fail message will pop up in the dashboard even though there is no bulb failing. Also, it starts to state that my tailgate is not closed while I drive it during the sunny day… (That means, it will become normal during the raining day…) The problem that accompanies with the tailgate issue is the cargo light sensor malfunctioning. Sometimes it light up all the day while driving, sometimes will not turn-on at all; but sometimes work normal during the raining day.

Dose anyone know what could be the core of these problems? I don’t want to take it to the repair shop for a whole day, and still can not find out the issue… :frowning:

Thanks a lot

2

I’d suspect a bad ground.

3

Hi Mike,

A bad ground sounds reasonable to explain the weather v.s. the sensor. It there anyway to check the ground by myself?

Thanks

4

Yes…there’s a way…but you have to know what you’re doing…and you’re going to need a schematic diagram. Bad grounds can be tricky to find.

5

I had a '98 and '00 V70XC wagons. Likely won’t help but it you want to try somethings yourself here’s what I’d do. Tail light out indicator; take out every light bulb you can access in the car (front and back). Clean all the contact points on the bulb and in the bulb socket or snap in connector. Put some dialectic grease on the bulb contacts and put them back in. You might get lucky and in cleaning all the contacts you solve the problem. Any bulbs that look dark with age, replace.

Find the switch that is tripped as the tailgate closes, it might be similar to the switches on the door jams. The switch could be defective. It might not moved enough when the tailgate closes which could be an adjustment to the tailgate hinge or latch. If you can’t adjust the tailgate you could build up the end of the switch so it will move a bit more and work properly.

If these are your only problems with an '01 Volvo you are very lucky. I sold mine years ago after way too many budget killing expensive repairs.

6

You can locate a bad ground by using a voltmeter with the common reference lead tied directly to the battery negative lead or another proven good ground point on the car. There will be no difference in voltage between the two ground points if things are good. Once you know you have a good ground reference point to start from then check the voltages at the suspected bad ground points while the lights are on using the other meter probe. You need current running through the circuit. A bad ground will have a voltage drop across due to the resistance and the meter will see a voltage there of something greater than zero volts.