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Are there any 'good' solutions that allow us to use LED bulbs on the tail lights and front blinkers? I borrowed a few and immediately found the bulb failure indicator stayed illuminated and the blinkers go into rapid fire mode. I know the LEDs draw less current and I expected these symptoms. But I like the lights - much brighter.
I've read about putting resistors in parallel and swapping out the relay for an LED-compatible unit. Are there any simpler solutions?
Thanks.
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I just took the sensor apart and replaced all the connections with jumpers. Who needs and failure sensor with LEDs?
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Besides the previously mentioned flasher unit made to work with LED lamps, there are numerous sellers of ballast resistors on eBay.
I have LEDs on two 940s using ballast resistors. The LED turn signals are bright. I also installed LEDs for the brake lamps. The Lamp Failure Relay is still installed, and I have no fault indication.
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john
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Hey John,
Granted you don't get any fault indication, but would you, if you, say, removed one of the brake lamps?
I'm not sure your 9-series Volvos use the same bulb integrity sensors, but I'd imagine they are testing the presence of the ballast resistors, not the lighting. I figure those ballast resistors were marketed to folks who had CANBUS cars.
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Art Benstein near Baltimore
"People that can use a test light, meter, a scope, and talk to the consumer without being mean to them can do very well in this growing industry. I've been an
electronics tech for 30 years so I know just how much fun this electronic stuff is." -Dave dl242gt
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Art,
I installed the LED lamps several years ago, and at the time all I could find was ballast resistors to make the turn signals blink at the standard rate (about 80 per minute?). If there were turn signal flashers which were not frequency dependent on load, I was not aware of them. The kit I bought had four ballast resistors, and I installed all four.
Yes, all that is being supervised is the ballast resistor. Removing an LED brake lamp from the circuit does not trigger the Lamp Failure Relay.
I believe the Lamp Failure Relay is the same for 240 and 740/940. Last year I trouble shot, and repaired a non functioning third brake light on a
1993 240 wagon. The LFR had failed. It was the same as used on the fleet of 740/940 that I have maintained for years.
I have head light relays on two of the 940s, and the relays don't trigger the LFR, as the small current load is balanced.
I know very little about the CANBUS system. All I know is that retrofitting a piece of equipment which communicates on the CANBUS system is not possible.
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john
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Hi John,
Thanks for taking the time to reply. I recall the days when this board was good for discussion, and not just for repair info not already in some go-pro video.
I didn't get that you used the resistors with the flasher, thinking you had used the special flasher relay. I assumed you used the resistors to retain the bulb warning function for the other lighting.
Also, I didn't get the reason for LEDs in the turn signals. If they are brighter, that's a significant safety advantage and worth the trouble. I'm used to seeing so many LED "upgrades" being done for other reasons, such as keeping the lenses from melting.
The upgrade rationale ignores the fact the lenses did not melt during the first 10 or 15 years of service with incandescent lamps; that the melting is from contact resistance developed with moisture and age, not bulb heat. Yet it can be argued the reduced LED current will also reduce the I-squared-R losses in the oxidized connectors, so the mod is likely to be successful in results. LEDs are best when designed in as part of the entire system, and that goes for any lighting application.
Regarding the BFWS (Volvo's term for it) I was aware some 9xx cars use the same one as 240's. My QRP (Quick Reference Parts) manuals from the early 90's show this, and also separate front and rear sensors for the 760 and 940SE cars. I recall someone posting about digging a sensor out of the back of a 9-something. Hence I've steered clear of offering help on the subject I know so little about.
It is ironic the reliability of the rear lighting especially, is thought to be weak from broken lamp filaments for the first 15 years or so, such that a bulb integrity function is needed, and thereafter made even worse by the aging of [solder inside] the sensor itself. And, that the whole reason you might add relays to the headlamps is to regain the voltage drop incurred in the wiring and connections to that bulb warning system itself.
Did you take any pictures of your ballast resistor implementation?
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Art Benstein near Baltimore
We can complain because rose bushes have thorns, or rejoice because thorn bushes have roses. -Abraham Lincoln
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So it looks like there is no simple LED conversion (well, at least what I would call simple!).
Thank you for the great responses.
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I use them successfully on the brake lights, the benefit is you don't melt the bulb holders and tail light!
Dan
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I'll second Carver - it's really not a big deal. I installed the following bulbs in mine to great effect:
Brakes/tails (unfortunately now unavailable):
https://smile.amazon.com/gp/product/B01MY4T4BU
Turn signals: (unfortunately not available):
https://smile.amazon.com/gp/product/B0739RCR3J
Front markers:
https://smile.amazon.com/gp/product/B01MXLZGR0
Reverse (these are bright enough to provide not just notice to other vehicles but some modest illumination in the dark):
https://smile.amazon.com/gp/product/B00EKKJDP4
Overall, the benefit has been greater visibility, as these are brighter than the bulbs they replaced - closer to a modern car. I also am assuming they will last longer, draw less power, and create less heat. If I don't have to dig around in those lenses as frequently, that alone is worth the added expense. I elected to put an LED in my third brake light knowing that the brakes would illuminate the bulb failure sensor. C'est la vie. At some point I'll try to figure out how to disable just that warning while keeping the failure light intact for the other lights.
As indicated, you'll want to replace your turn signal relay with one that supports LEDs without rapid blinking. This will cost you a few bucks at the local auto parts store. Don't look for the exact vehicle match - just match the particular three pin configuration. It's a two-minute install.
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"At some point I'll try to figure out how to disable just that warning while keeping the failure light intact for the other lights."
Kinda complicated, again, depending on your incentive.
The headlights are the only bulbs left in your setup to qualify for bulb failure warning. The current needed to unbalance the magnetic field operating the reed switch is chosen for the incandescent load. Incentive is low, because it is pretty easy to see when a headlight fails.
You could hack your sensor and at least disable the third brake light portion of the sensor by finding resistor R3 (8.2 ohms gray-red-gold) and snipping one end of it, but all that will do is stop the warning lamp from lighting every time you step on the brake. It won't help you if one of the LED tails or stop lamps loses connection -- which is the much more likely event than is LED-bulb failure.
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Art Benstein near Baltimore
A place for everything. Everything in its place. Granularity may vary. -AB
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You'll need this turn signal relay
https://www.autozone.com/electrical-and-lighting/turn-signal-flasher/novita-turn-signal-flasher/849390_642027_11714
Pretty sure it was the third brake light that set off my bulb indicator but I bypassed it.
Lenses should last a lot longer, it's the heat from incandescent bulbs that cooks them from the inside out.
Recently went LED for everything on my '90 245, no issues so far.
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There are turn signal flashers designed to work with LED replacements. I recall seeing them when looking for flasher relays with audibility enhancement for the hearing impaired. The bulb integrity function is part of your flasher, the three-pin relay clipped to the left support of your front console. An auto parts store should have someone able to look them up.
But the tail lights, brake lights, and head lights all depend on the bulb integrity sensor specific to Volvo (I think only Volvo) which measures the current magnetically. The problem here is the third, high-mounted brake light. It is measured separately, whereas the tails and headlamps are compared right and left. If only the tail lights were LED, it would still balance, but because your tail lamps share a bulb with brake lamps, you will get the bulb-out indication from the brake light portion.
Yes, it is complicated. First of all, there is little reason to LED the turn signals, besides the snappy response time for looks, and doing the more practical LED conversion of the troublesome tails and brakes on a sedan, for instance, you'll have to give up the bulb integrity warning or become complicated. The complications DIY make it even less reliable than the incandescents were in the moisture and cracked lens environment.
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Art Benstein near Baltimore
Eat, drink, and be thoughtful.
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"you'll have to give up the bulb integrity warning or become complicated."
As you mention, it appears to be specific to Volvo. With LEDs being quite reliable, why not bypass the bulb integrity warning module?
I haven't taken a look at the wiring to-from the module but I don't think it would be too hard to do. Am thinking of converting to LEDs myself soon (next Amazon order).
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1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.
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Find a truck site that addresses this issue.
Truckers have been adding led lights everywhere.
Try Grote's site, Truck Lite, or a local truck accessory shop.
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