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I have the 1990 Volvo 240 and my brake lights aren’t working on it. The switch, fuse, and bulbs are all fine. I had a major short not to long ago which started a fire at the left rear tail light and I fixed the short at least I thought. But rite now if I jump a wire directly to the left rear brake light the right and third lamps illuminate but only if the brake pedal is not depressed and the lights are on. If I press the brake pedal I get no lights at all. Help……
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Ok so I’ve looked at the wiring diagram and everything i saw in the car that matches up to this diagram looked fine. I’m going to test the switch and see if the issue is there.
Using the wiring diagram will help alot.
Make sure you have power going to the switch, then check for power leaving the switch when the switch is depressed.
You could also try and ohm out the switch is you remove it.
Also do a good visual inspection of the brake pedal linkage going to the switch.
http://bbbind.com/tech_database.html
You need to follow a wiring diagram. How do you know the switch is good? Do you have a DVOM or at least a test light? If you are jumping current past the control of the circuit, and the lights light, then you have a good ground. So the issue must be between the battery/fuse box and the lights, which obviously includes the switch.
I thought that link would take you directly to the diagram, which is very basic. The only oddity I saw was a failed bulb sensor in there. All the brake lights run through it. But I would still be suspicious of the switch and then work your way down the diagram.
Third try: If you click on that link, then click on the red Wiring Diagrams button, it should take you right to the diagram I was looking at.
No matter what I do the left brake light doesn’t work at all. I’m 100% positive the bulb is good as I’ve moved switched the bulb over to the good circuit. But I do have a test light and a DVOM. And because the connector is fried due to the fire I spliced in a wire and jump it directly to the brake light bulb so the bulb failure light is always illuminated. But no I’m not sure if the brake light switch is working but I want to make sure everything else is ok before I go and buy a switch that might be fine.
What wire are you jumping to make the lights come on? If you turn the head lights on do you get rear lights?
pull the connector on the brake switch.check the brake switch with an ohm meter to see if it makes and breaks.
next test the connector for 12v you should have it on one side. if you jump the connector see if the lights
come on. if not than problem is from there back. if no power at the connector then the problem is from the connector
forward.(power source) You may need to recheck the wiring that you fixed. Also you may have melted a connector
some where. Once again recheck the fuses. good luck and keep us postedC8-)Believe it or not electrical problems are often straightforward you just need to know where to look and you start with a good wiring diagram, don’t neglect the ground side of the circuit because it’s just as important as the power feeds. If it were me I would begin my checking at the brake lights to see what you have back there, if you don’t find that you have feed voltage with the brake pedal depressed then work your way back to the brake light switch. Don’t forget to check ALL the fuses, sometimes just one blown fuse can cause other circuits to have issues so make sure you check those first. As for your testing of the brake light switch be sure to check the continuity of the switch with it unplugged to verify it’s operation.
ok i dunno if it will help any but i do have tail lights and no fuse are blown and all wiring is good. I found that there is power going to the switch but the switch isn’t working. I think when the fire started it shorted my switch out. And if after i put the new switch in and it still doesnt work I might just re wire it.
Jump the wires for the switch. this will prove if the switch is bad. if the brake lights come on its the switch. if they don’t
then you need to work from there back.C8-)well it’s only a one wire switch and I tried jumping the wire between the connectors and it did nothing. I might have to try to touch it to a ground or something.
don’t ground anything at the switch. you will cause a short. according to the print. there are two terminals #1 wire 15 green with red
terminal#2 wire 10 blue with red. these are the two wire switches. jump these wires to see if your tail lights come on.C8-)One of the clinical pearls of electrical diagnosis is that weird problems are often caused by bad ground connections. Strangely, ground can sometimes find a pathway backward from other devices, causing electrical flow the wrong way down a seemingly unrelated wire. So, when you methodically trace the problem down, don’t be surprised if it turns out to be a bad ground.
After checking fuses and relays, start backwards at the bulbs. Then work your way to the pedal. Jumping the switch is a good idea too. If they still don’t come on, then the switch is probably good. But before all of this, you should get a wiring diagram.
Ok so I’ve done everyone’s suggestions and I jumped a wire at the switch and I got nothing. I searched as far as I could for a short and I found nothing. I traced the wires as far as I could in both directions and I didn’t find anything. Plus it looks like some one was in there before me and possibly messed everything up as there’s electrical tape around everything and zip ties all over the place where the wiring is. But what I’m thinking of doing is re wiring the brake lamp system my self. Possibly by passing the bulb failure circuit. If I were to re wire it I would run it directly from the battery through the fuse to the switch to the lights. As long as it’s a 12 volt circuit could I do this without much issue?
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