SwedeSpeed - Volvo Performance Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
606 Posts
Discussion Starter · #1 ·
My brother has a 1986 240 up in Seattle with no brake lights and only the right rear driving light working. I am helping him diagnose it remotely and after doing some reading and checking all the usual stuff (fuses, brake light switch, bulbs, etc) we think that it is possible the bulb integrity sensor.

Could a bad sensor cause only one light to work in the rear? Is there a good way to test it? Anything else we should check?
 

·
Premium Member
Joined
·
19,953 Posts
My brother has a 1986 240 up in Seattle with no brake lights and only the right rear driving light working. I am helping him diagnose it remotely and after doing some reading and checking all the usual stuff (fuses, brake light switch, bulbs, etc) we think that it is possible the bulb integrity sensor.

Could a bad sensor cause only one light to work in the rear? Is there a good way to test it? Anything else we should check?
Assuming this is a sedan check the wiring inside the trunk where it flexes, at every junction/ground and where the wires enter the bulb receptacles.

Yes, a faulty/failing bulbout sensor can kill some lights and can also cause problems with the cruise control.

Check the brake light switch/wiring at the brake pedal and be sure the entire braking system is functioning and without leaks.

Be sure all bulb sockets are in good order and making solid contact with the bulb.

Confirm that all fuses have the correct amps and are making solid contact.

Consider purchasing new twin-packs of each bulb application then install them all at one time. This eliminates a common problem with the lit bulbout sensor.

George Dill
 

·
Registered
Joined
·
606 Posts
Discussion Starter · #3 ·
It is a wagon. We have had issues before with the harness in the hatch on a different 240 wagon, but I think that only effects the brake light in the window. The car doesn't have cruise control so I can't check that. He has checked the brake light switch and all of the fuses as well as the bulbs. May have him try replacing all the bulbs to be sure because that is pretty cheap. Thanks!
 

·
Registered
Joined
·
3,126 Posts

·
Premium Member
Joined
·
19,953 Posts
It is a wagon. We have had issues before with the harness in the hatch on a different 240 wagon, but I think that only effects the brake light in the window. The car doesn't have cruise control so I can't check that. He has checked the brake light switch and all of the fuses as well as the bulbs. May have him try replacing all the bulbs to be sure because that is pretty cheap. Thanks!
Checking the hinge wiring requires pulling down the headliner and finding enough slack to get a test meter probe in all the right places. Once you confirm power to the fuse terminals controlling rear lights follow those wires to the back tailgate hinges then on to the bulb sockets. Even if the wires at the hinge look ok what often is missed is the break hidden under the stretched wire insulation.

Are you familiar with 240 wagon relays?

George Dill
 

·
Registered
Joined
·
606 Posts
Discussion Starter · #6 ·
Checking the hinge wiring requires pulling down the headliner and finding enough slack to get a test meter probe in all the right places. Once you confirm power to the fuse terminals controlling rear lights follow those wires to the back tailgate hinges then on to the bulb sockets. Even if the wires at the hinge look ok what often is missed is the break hidden under the stretched wire insulation.

Are you familiar with 240 wagon relays?

George Dill
If it was the hinge wiring, wouldn't the side taillights still work though? I thought that was just the rear window brake light and the rear window defrost?

I am not familiar with the wagon relays.
 

·
Premium Member
Joined
·
19,953 Posts
Large download...

http://www.k-jet.org/files/greenbooks/TP30808-1_wiring_diagrams_1985_PRELIM.pdf

...so may be best to save a copy once download is complete..

The brake and reverse lights wiring on the wagon are accessed "behind" the driver's side rear cargo panel and are not in the hinge but a short in the hinge wiring may affect rear lighting.

The above pdf also covers relays.

Once you are certain that power is reaching the brake lights then work on the grounds and bulb receptacles.

George Dill
 

·
Registered
Joined
·
606 Posts
Discussion Starter · #8 ·
Just to follow up on this it turns out that it was a combination of things. First off, he checked the fuses but not very well and one or two had bad connections (even though the fuses were intact). Also, there was a bad buld or two. With both of those fixed, the rear lights all worked as expected except the brake lights. So I am sure that it is the brake light switch behind the brake pedal since the fog lights work fine. It turns out I won't be replacing it and he may not anytime soon because when working on this we discovered much more serious issues with some oil and power steering leaks. Thanks for the help!
 

·
Registered
Joined
·
3,126 Posts
One thing about tailgate wiring is that not all of the wires split at the same time. As an example, on my '92 245 it's just the rear wiper wire that's split and the others are OK; for how long, though ... :rolleyes:
 
1 - 9 of 9 Posts
Top