850 wagon base, turn, hazards and high beam blows fuse

[RickHaleParker]

The obvious thing I missed here is to completely disassemble the area were repairs were evident. From experience, about 90% of electrical repairs on cars is garbage

I suspect that the "repair" is miswired or they did not find the root cause of wire damage.

[JimBee]

The #12 fuse on my 93 850 was blowing, taking out my brake lights. I went through a lot of tests like you've done. Finally, a Volvo indy shop tech clued me that the bulbs need to be matched. I checked, the tail light bulbs were not matched for wattage. Installed a new matched set and that solved it.
The blue box behind the trim panel, rear left, apparently regulates wattage balance. I replaced mine with one from the junk yard but it wasn't that, just the unmatched bulbs. That blue box would be worth a look if the bulbs are matched.

One other fail point comes to mind. The front turn signal sockets on my 850 got corroded. They didn't blow fuses, just left the circuit open. It's possible, I suppose that you could find a poor connection in one of those that is drawing higher than normal amps. Also make sure the bulbs in those are the right ones and matched.

[RickHaleParker]

I checked, the tail light bulbs were not matched for wattage.

Pull all the turn signal bulbs. 1157A on front, 1156 on rear.
If correct, See if the fuse blows without the bulbs installed.
If it does not, add bulbs back one at a time until it does blow.
After the fuse blows, pull all the turn signal bulbs again except the one it blew on.
If it does blow with just one bulb, the problem is on that circuit.

[TerrDawg]

JimBee .... What the What !?!
I did check the bulbs however, 16 years in the body shop and I've never heard of this, am blown away and will definetly do this, afterward I'll check the blinker fluid and the piston return springs haha, seriously I did check the connection and look for corrosion (replaced both fronts from IPD ) but would never think of wattage differential being a culprit .. Anxious to see if all new correct bulbs work, I had tried the remove all 4 corners but didn't work out
If that's the deal, I'm sending a $25 gift card, goes for anyone that wins the dial-a-Volvo-problem
Thanks and Happy New Year !!
Terry

[TerrDawg]

Well, all 1156 and 1157 bulbs ($30 bucks) are new and have same wattage ... And it works.... For about 5 minutes. Still blows fuse, so anyone else with wives-tale, rumors, SWAG method (scientific wild-assed guesses) or actual incidents of relief are encouraged to put your thoughts on this page for a $25 gift certificate... I figure I'll check ignition zone for a pinched wire then replace each corner of wiring going to the bulbs and then rewire dash from the bulkhead to the switch - if that fails I'll put on of those 70's diesel turn signals on the column and maybe aftermarket lamps... Look for a blue 850 with lights on the roof hahaha
Thanks again for all your help
I did find out that there is merit to the wattage theory .. It apparently has to do with the light monitor on the dash, you know the one that tells you a light is out

[RickHaleParker]

Did somebody substitute a lower rated fuse sometime in the past?
Fuse 13 should be 15 Amps. Fuse 13 also powers the Alarm system.

[TerrDawg]

It's 15 amp but maybe time to check alarm, didn't know it shared the fuse, or forgot
Thanks again for the help

[wizechatmgr]

Wish they made something similar to a fiber break detector for electrical shorts.

Closest I see is this https://www.amazon.com/FF310-Short-Circ ... B000XVZ8F8

We used something similar in wiring closets on the job. This one is low voltage.

[RickHaleParker]

Wish they made something similar to a fiber break detector for electrical shorts.

There is, it is called a Thermal Imager. Low end ones start at under $200.00

[wizechatmgr]

Wish they made something similar to a fiber break detector for electrical shorts.

There is, it is called a Thermal Imager. Low end ones start at under $200.00

So a FLIR style camera?