I have a light on my rev counter showing that a bulb is inoperative, I've checked every bulb and they're all lit or work as they should.

I've just changed the indicators on the wings as one was bodged with a screw in the bulb holder and the other was a bit rusty too (changing them wasn't as easy as I thought it'd be!) on the NS I probably didn't put the earth wire in the same hole it came out of on the connection block, this wouldn't cause the issue would it?

 

In a way, yes!! Contacts and equal bulbs are everything to the devices sensor. An "off' lamp or socket and the bulb out lamp will remain lit. Just as if one was "burnt" out.

By the way, mine fooled me for a time. It lit up on starting up. I did not realize that was normal and an advice that it was operative I thought it meant somewhere a lamp was dark. No it went out and that meant all was well.

Plus, not all bulbs are sensed by it!!

Carl

 

Hi Justin,
To start with, is it the bulb failure light or the turn signal repeater in the tach / rev counter that is on ? If it's the failure light, do both the instrument panel turn signal repeater lights work correctly ? Does the light stay on regardless of what you have selected on the headlight switch ? I think the side repeaters you replaced should only function as turn signals and are NOT checked by the bulb failure units ( if installed ). My 1985 Sovereign ( German Market / "Grey market" import to USA ) has only the brake bulb failure unit in the boot, the other five were never installed that I can tell ( the reds are connected together and the white failure wire taped off ). A easy check would be to remove the panel in the truck ( that covers the ECU etc ) to see if those 3 plus the brake failure unit are there. If they are not installed then I think your problem might be with the brake light circuit. However if it's the turn signal repeater light on the dash that's staying on, then you might have the hot feed to the side repeater grounded which might make it stay lit. The other fun possibility is that the wiring has been modified or bodged before your ownership.

Do you have the S57 Wiring book ? It is made for USA models so there will be differences on some of these circuits but is still a must have. You can download it from Jose's site or I can post a picture of the circuits to help you trace the problem.
I THINK I've figured out the Euro vs USA wiring scheme differences, and have a few suggestions on how to make the repeaters work as both running lights & turn signals as well as modifying the front bumper signals to do the same ( Using Jose's modification with changes for the Euro wiring ).

Hope I'm helping instead of being confusing !

Cheers,
Brian

 

I agree. Over the years I've never heard of bulb failure modules on the the turn signal bulbs/circuits.

Cheers
DD

 

One of the BFUs (Bulb Failure Unit) may have failed. You'd have to unplug 'em one-by-one to find the culprit

Or......

Maybe you have some incorrect bulbs?

The BFUs are simply a bi-metal switch that responds to the heat of the current that passes thru them. They are calibrated to respond xxx-amount of heat. If bulbs of lower amperage draw are installed then less heat will be generated and the bi-metal switch will not open up.....and the warning light on the dash stays lit.

Cheers
DD

 

Going along with Doug's post about the BFUs requiring a set amount of current ( power drain ) to work correctly, LED's don't pull enough to turn them off either ( as noted in many posts here ). A quick and simple way to bypass them is to just unplug the white / slate wire from the BFU or even better, just jumper the reds together and leave the white hooked up thus making sure you get all the voltage going to the bulbs you can. Just be sure to tape / insulate the jumpered connections so they can't short out.

Cheers,
Brian

 

I lived most of my life without the luxury of a bulb failure indicator. So when I switched over to brighter LED bulbs in my series III I just gave the tach a quick twist and took the bulb out of the indicator.

When you get to the point "the failure unit failed", things are too complicated.

Jeff

 

Thankks, doug, for the clear description of how the bulb failure units work . My recollection was along that lie, but less clear

Carl