2001 V70 2.4T Brake light problems

[abscate]

Your 2001 REM is different but here is my pain on the 2005

viewtopic.php?f=9&t=73056

[prwood]

Ok, I did some additional diagnostics this weekend:

1. I tested out all of the components that run through the REM: rear heated window, parking lights, tail lights, reverse light, rear fog light, brake lights, locking systems. Everything worked except for the left and right brake lights (the high mounted brake light worked). So I am fairly confident it is not an REM issue.

2. I swapped shunts, fuses, and relays between the brake light and other components on the REM. Parts that worked properly with other components did not make the brake lights work, and parts used for the brake light did not cause other components to fail when swapped over. So I don't think it's a fuse, relay, or shunt issue.

3. I got a 12v battery and hooked it up to the pins in the upper tail light assembly connector. The reverse lights (which are mounted above the brake lights) came on properly, but not the brake lights.

4. With the same battery, I tested the metal contacts that carry power from the connector to the light bulb socket. Seen in the diagram below:

IMG_8374.jpg (288.22 KiB) Viewed 319 times

Touching the contacts for the reverse light (1+2) caused it to come on. Touching the contacts for the brake light (3+4) did not cause it to come on.

5. I took the sockets out of the assembly and touched the battery leads to the contacts on the socket. All of the bulbs (both reverse and brake light) came on normally.

6. I used a multimeter to read ohms resistance with the sockets installed in the assembly. There were 0 ohms resistance when testing contacts 1+2 for the reverse light, and infinite resistance when testing contacts 3+4 for the brake light.

My preliminary conclusion is that the contacts for the brake light are bad (either their contact points with the electrical connector are weak/broken or they have failed in some other way) and that the brake light assemblies need to be replaced. It would not surprise me if this is the case, because the construction of these contact points seems incredibly frail - very thin metal with some minimal plastic molding holding it together. However, I was hoping someone could validate my testing methods in case I am coming to the wrong conclusion.

I have found that Erie Vo-Vo sells the tail light assemblies for $55 each which is not too bad.

Thanks!

[firstv70volvo]

Ok, I did some additional diagnostics this weekend:

1. I tested out all of the components that run through the REM: rear heated window, parking lights, tail lights, reverse light, rear fog light, brake lights, locking systems. Everything worked except for the left and right brake lights (the high mounted brake light worked). So I am fairly confident it is not an REM issue.

2. I swapped shunts, fuses, and relays between the brake light and other components on the REM. Parts that worked properly with other components did not make the brake lights work, and parts used for the brake light did not cause other components to fail when swapped over. So I don't think it's a fuse, relay, or shunt issue.

3. I got a 12v battery and hooked it up to the pins in the upper tail light assembly connector. The reverse lights (which are mounted above the brake lights) came on properly, but not the brake lights.

4. With the same battery, I tested the metal contacts that carry power from the connector to the light bulb socket. Seen in the diagram below:

IMG_8374.jpg

Touching the contacts for the reverse light (1+2) caused it to come on. Touching the contacts for the brake light (3+4) did not cause it to come on.

5. I took the sockets out of the assembly and touched the battery leads to the contacts on the socket. All of the bulbs (both reverse and brake light) came on normally.

6. I used a multimeter to read ohms resistance with the sockets installed in the assembly. There were 0 ohms resistance when testing contacts 1+2 for the reverse light, and infinite resistance when testing contacts 3+4 for the brake light.

My preliminary conclusion is that the contacts for the brake light are bad (either their contact points with the electrical connector are weak/broken or they have failed in some other way) and that the brake light assemblies need to be replaced. It would not surprise me if this is the case, because the construction of these contact points seems incredibly frail - very thin metal with some minimal plastic molding holding it together. However, I was hoping someone could validate my testing methods in case I am coming to the wrong conclusion.

I have found that Erie Vo-Vo sells the tail light assemblies for $55 each which is not too bad.

Thanks!

Based on your measurement results the bulb socket metal contact tabs are not making good contact with the metal plate contact areas in the tailight assembly. Either the pins are bent into the socket too far and not making good contact with the taillight lens metal plate or there's corrosion on the socket metal tabs or where the tabs contact the metal plate when the sockets are twisted in. Sometimes the plastic in the taillight assembly becomes damaged from heat and the bulb sockets doesn't hold in place when twisted in but from your photo that doesn't look like the case.
Clean both the socket metal tabs and tailight plate contact area with something abrasive like a small wire brush or fine grit sandpaper and then clean off well with electrical cleaner if you have it.

Here's one of the two brake light bulb socket metal contact tab that has some obvious corrosion but they can also look pretty good and still not make good contact. Make sure the socket contact tabs aren't bent inward too far or cracked, they need to have good pressure against the metal plate in the taillight lens assembly when the sockets are twisted in.

brake light metal bulb socket contact tab corroded some.jpg (208.15 KiB) Viewed 312 times

Be sure to clean this area of the metal plate well where the socket contact tabs slides as the socket is twisted in, note the stripe shiny mark on the plate made by the socket tab, that's the area to clean well. Overall, there needs to be good mechanical contact with both brake light socket metal tabs and electrically clean metal on both sides.

brake light contact area for bulb socket tab.jpg (307.15 KiB) Viewed 312 times

[jonesg]

It looks like you found the problem.
Doesn't surprise me in the least.

the older volvo's 240 and 740 models had the same problem but worse , the metal traces actually melted.
The traces were like tinfoil.