94 850 Sedan Tail Lights Gone Mad

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Hi All --

I've been trying to resolve a turn signal / tail light array issue. When I don't have my headlights on, depressing my brake pedal brings up the bulb out warning on my dash. The brake lights show on the tail light array of the car. If I have my turn signal on, it works on the dash and tail lights until the brakes are applied. Then the dash signal speeds up and the tail lights go solid. Backup lights work, running lights work. All until the headlights are on, and then the bulb out dash light runs continuously, and the fog light dash light faintly glows, and the turn signals don't work at all.

I've been reading Lee's and other helpful posts on the forums. Before that, I checked all fuses, replaced all lights, replaced the headlight relay, and, when I noticed my cruise control would turn off with a turn signal application on the highway, even replaced the turn signal cruise control switch. Nothing has resolved the issue. I haven't checked the brake switch (though my ECU has long shown fault 141 and 142, even after replacing the sensor, but hasn't had any obvious deleterious effect in the past). All bulbs have been replaced (and contacts cleaned) with a complete kit from fcpeuro. I pulled out the Bulb fault control module from the trunk, opened it and didn't see any issues, and put it back.

I now have ordered both a warrantied used headlight switch and bulb fault module via ebay. But, given a couple forum posts, I now suspect the issue is the turn signal relay in the hazard light switch module. I'm a bit of a duffer at this and going about it by trial and (mostly) error.

Any suggestions would be welcome. I have 10 days until inspection. This forum has helped me through a number of issues. Many thanks to all of you who take the time to respond.

Best,

Jim in DC

[MoVolvos]

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What was done on the car before all this started?

Blessings,

BKM

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[[email protected]]

I noticed that the turn signals were acting up about a month ago. Things have gotten progressively worse.

I just inventoried the tail light functions:

With the head lights off:

Hazard Switch on: Yellow tail light flash and front side panel lights flash, dashboard "bulb out" flashes.
Left and Right Turn Signals: function with "bulb out" light flashing on dash.
Brake Light: functions with "bulb out" light on.
Brake and Turn signal on simultaneous: Left and Right Rear brake lights flash, and the opposite of the turn direction light flashes dimly

just ordered a replacement Hazard light switch / relay. From what I've seen discussed, it seems the most likely culprit. But I haven't done well yet in assessing things.

[[email protected]]

With the Headlights on, things are worse:

Turn signals flash both rear running lights and faintly the center stop light.

I have done no electrical work on the car recently.

[taxi]

Hi! Do you have a tow bar? The connector can cause strange issues. If you do have it, there is also a connector in the boot to unplug it.
Good luck!

[loub]

I had a similar problem with my 94 850. The right side tail light bulb panel was shorted ( the plastic panel that all the rear bulbs are secured in). I got one from pick n pull for $ 10 that solved the problem. If you go that route, take the old panel to make sure the tabs line up to fit properly.