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Deleting Bulb Failure Circuits

But pulling the bulb from the cluster has given me many days of worry free driving. I always check my bulbs on a regular basis anyway.

That is a great idea. Pulling out the dash anyway to fix a solder joint that makes my gas gauge erratic. Ever since my rear fogs in the 88 765 got working that warning bulb lights up when the brakes go on with the fogs. A new bulb went in the CHMSL (or something like that...the middle brake light) and my system does not like the combination.
 
Uncle JohnLane,

Very good idea-r!

The low beam light bulbs are much brighter without the bulb integrity sensor, yet that current goes through the dashboard headlight switch whether one has a bulb integrity sensor or no.

In what and how many ways can we call the "bulb integrity sensor"? Bulb out sensor? Bulb failure sensor?

So, you are saying using the current through the bulb integrity sensor to actuate a relay that powers the low beam filaments, yes? That obfuscates the bulb integrity sensor operation, yes, as the bulb integrity sensor would only see balanced current through that side of the relay. No feedback through the relay.

I'd still rather do away with that sensor and make use of relays that bring full current to the filaments. I have all 86+ big square plastic headlamp assemblies. So, I'd hope, with full current, the plastic crappy U.S. DOT headlamps can take fully power filaments using the proper bulb model at the designated watts (current [amp] draw at volts).

A worthy effort to undertake, eventually. I'll consider it while preserving the dash stalk hi/lo beam actuator.

If you'll note, on the 1985 and prior bulb system, the ho/lo beam relay can carry more current draw. The newer giant square plastic bulb system carries a smaller current limitation through that hi/lo beam relay, yet the same pinout, I think.

I miss my 1979 242 GT with the two single beam big round sealed beam headlamps. These were both stock and bright with the old bulb integrity sensor in the black canister Uncle Art points out as the durable model, yet unable to work with the third brake light system.

In my experience; turning on the lights via relays does not trigger the bulb integrity sensor. You'd better be able to see if you've got a headlight out.

Using a pair of relays next to the battery to get power to the headlights ensures that full power gets to the headlights.
No plus in having that amperage finding it's way through the car via how many miles of wiring for how many voltage drops before it finds it's way to the headlamps for what ends up maybe 12-13 volts.

Many of us have given our cars big wattage Halogen lights..... More amps. HID kits installed correctly; aimed safely will make for more light in color for our old eyes with less amps used.
 
My warning light blinks with my right turn signal, but then it also comes on when I roll down the window. Then it turns off when I hit the brake pedal.
Someday I'll have to look at that.
"89 245, BTW.
 
Connect
2,6, and 7 Low beams
3,4, and 5
9, 10, and 11 Brake lights
12, and 14 Right side park and tail lights
13, and 15 Left side park and tail lights

Pin 1 is power from the bulb out light, when the reed switch closes it grounds the bulb out light through pin 8, turning the light on.

Hey folks, hate to bring this thread back from the dead, but I wanted to to correct it. For my 740, I had to connect pin 5 to 9, 10, and 11. According to all of the wiring diagrams for a 740 I could find (And I checked!), pin 5 goes to the "upper level brakelight". My third brake light didn't work until I connected it.

Tl;dr- Connect 5, 9, 10 and 11 to make the brake lights work.
 
Hey folks, hate to bring this thread back from the dead, but I wanted to to correct it. For my 740, I had to connect pin 5 to 9, 10, and 11. According to all of the wiring diagrams for a 740 I could find (And I checked!), pin 5 goes to the "upper level brakelight". My third brake light didn't work until I connected it.

Tl;dr- Connect 5, 9, 10 and 11 to make the brake lights work.


Your info is correct for '86 and later sensors. The other info was correct for '78-'85 sensors.
Dave
 
Wanting to jumper these pins but having difficulty opening up this can and don't want to destroy it. How do you guys open it up?
 
I show a method to do this in my page without having to use the sensor ever again:
http://www.davebarton.com/volvo240mods.html
Scroll down to Bypassing a Volvo Bulb Failure Sensor, Part 3 of 3.
Dave B

terminalrelaybypass.jpg
 
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Question about this old thread:

I have an 88' 745 with the red bulb failure sensor. I would like to bypass the bulb failure components sensing the low beam headlights only and keep the rest of the system functional. I.e. Have the bulb failure warning light in the dash come on if I have a taillight, brake light, or parking light out but not a headlight. I'm terrible with wiring and don't want to damage anything.

About the bridging of pins: would I be able to connect the wires going to pins 2,6,7 before they connect to the sensor, leaving everything else the same?

Here is a link for the bulb failure relay http://www.davebarton.com/pdf/bulbfailure86-93.pdf

Hopefully this makes some kind of sense

Thanks for any help
 
^You can tie both sides together and that'll bypass the bulb failure sensor function on the headlamps. I'm suspecting that you're adding relays for your headlamps? It's pretty easy to do. Run both low beam wires to the trigger contact on one relay, and both high beam wires to the trigger contact on the other relay.

-J
 
Yep, adding relays. Thank you much for the information.

After I posted I realized it would be easier/less work to make the connections in the bulb out sensor if possible. How would I go about doing this?

From Dave Barton's page that is linked and similar to what Kitty's Grey Volvo did:
Can I connect pins 2,6,7 on the sensor and leave it alone? Or connect the pins on the sensor and then remove the wires connecting the pins to the circuit board in the sensor?


Sorry for having to ask another, likely confusing question but I appreciate the help.
 
On my 88 765 there was a separate rear bulb out sensor at the back of the car. The tricky part was figuring out how to bypass it when it burned out.
 
It's going to be a lot simpler to just tie everything together at the front of the car, instead of modifying the sensor, then trying to get the relay/fuse tray out to modify the wiring in the center console. Also, if the sensor fails, then, you'd have to redo the modification to another one.

-J
 
With all the problems 240s have with contacts, connections, and wiring in general I think the sensor is way to sophisticated (if that's the right word). Call me old, but I walk around the car once in a while just to check if everything is working.
 
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