Ok, I put it in park one day with the headlights on, and the bulbout light started fadeing in and out like a loose connection somewhere and then finaly went out all together. All the lights are working at this time! Also noticed that while rolling up the window, the bulbout light goes out period, then lights up when I release the DRIVERS window switch! Turned the headlights off then on again then it came back to a steady glow... How can I troubleshoot this dang light! I want it fixed right to where it don't light unless a bulb is out. Does the blk groundwire mounting to the frame from the tailights control part of the bulb out light functions?? If it is rusty, will this keep the light on?
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```1990 volvo 240dl sedan. 202000 mi, broken odo, work car, in need of major tlc! or i just need another cheap nicer volvo~~~

xpdude,

Your train-of-thought writing style is a bit difficult to decipher. I know that you know what you meant but I am not sure that I know that I know what you meant. ;-)

However, I think I gleaned the problem: The bulb warning light comes on with the headlights. Changing loads on the electrical system while the headlights are on causes the warning light to dim, pulse, or go out altogether. The warning light comes on steady again when the load is removed.

Are those the symptoms? Do you ever see the warning light with just the parking lights on? That would localize the problem to the tail lights because the front parking lights are not monitored. The turn signal bulbs are not directly monitored but, they can cause the warning lamp to flash.

Does the blk groundwire mounting to the frame from the tailights control part of the bulb out light functions?? If it is rusty, will this keep the light on?

Yes, and yes. Check all the grounds. Follow the wires back from the headlights, and tail lights to find the ground points. Clean them all.

How can I troubleshoot this dang light!

First, you need a wiring diagram for your car that is easier to read than the Bentley manual (a reduced copy of a Volvo schematic that would have been difficult to read in color and full size; it is almost impossible to read in black print in the manual).

Here is a source for schematics that are easier to read: http://volvo.techno.org.pl/schematy.html. The schematic for your car is listed at the bottom of the page.

Then you need to understand how the lamp warning circuit functions. If you have a Bentley manual, check out page 350-6. That is the only diagram of the bulb sensor I've seen. It is relatively easy to see the functionality. You can see what looks like a switch located between pins 1 & 8. The idea is that the current through the sensor is balanced if all loads left and right are equal. If you loose a bulb on one side, the current through that side is reduced causing an unbalanced circuit, closing the switch contacts, making the circuit complete to turn on the warning lamp.

The headlight circuit is fed from the Step Relay (hi/lo beam) on pin 6; output to the left side is on pin 2 and to the right side headlight on pin 7. If you follow that circuit out, you will see that only the low beams are monitored.

The tail light circuit is fed on pin 14. The brake light circuit is fed on pin 9. You can decipher the rest, I'll bet. Notice that pin 5 is connected to the high mounted brake light. It is the only circuit monitored that does not have a left side and a right side. I am not sure how the sensor is wired internally for the HMBL, but I can promise you it is not wired as shown in the Bentley manual. In order to function, it must be connected to pin 9. That means that the HMBL is not monitored.

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Mr. Shannon DeWolfe -- (I've taken to using Mr. because my name tends to mislead folks on the WWW. I am a 52 year old fat man