alexdimen

iTrader: (13)

i was having problems with my running/int lights and had to resolder the switch pins. i sucked up all the old solder, fluxed the pins and layed new beads. i have some good experience with soldering...

i installed everything and it all worked fine (had been completely out) until 15 minutes down the road they went out again! i got out of the car after i pulled over and by time i got around back to check to see if i had rear lights, they were all back on again. they stayed on for the rest of the ride.

what's up with that?

also, while i had the soldering iron heated i decided to try and resolder my cpu pins to get my door chime back and (a guess) my seatbelt light to stop flickering. no luck there either. resoldering just made it intermittent. i cleaned off all the flux after i was done too.

so, is it my technique or is the circuit fucked somewhere else?

Icemark

I have covered quite a few times why the headlight switches burn out.

Did you replace the headlight switch harness at the same time as the switch?

The most common reason for the headlight switch to fail is that the parking light bulbs have not been maintained. In many of the bulb sockets you may find corrosion. This increases the load on the switch and over heats the connections at the switch (burning up both the headlight switch and the headlight switch harness. Never ever ever re-use a damaged headlight switch harness as once the connections have been burnt, they will increase the resistance and cause the failure all over again. Bulbs (when ever replaced or corrosion is found in the sockets) should have a coating of conductive grease when installed to prevent the corrosion from being and issue.

Also any additional lights on the parking lights circuit can cause the switch to overheat and burn out. Always use a relay for any additional lights.

The third reason for failure is a cold solder joint in the switch (but this really only happens about 10% of the time). This cold solder joint happens where the pin meets the circuit board and will again cause the same problems.

I do have rebuilt headlight switches available on my webstore as well as a relay kit for increasing the load and protecting the headlight switch from being overheated and overloaded. But you do need to fix the bulb sockets and headlight switch harness before using either.


Please note that in my rebuilt headlight switches, I do not re-heat the solder joints, but rather remove the solder and flow new solder in... just re-heating locks the same colder solder joint and flux into the middle of the joint. If you are doing it yourself, you must remove the old solder... not just re-heat the joints.

alexdimen

iTrader: (13)

i noticed nothing wrong with my harness. i read the FAQ about it and have seen threads on this subject... i imagine i would notice my harness was burned up by looking at it.

i did in fact have cold solder joints. i've been dealing with this all over my electrical system.

i noticed the bad joints as soon as i took the switch apart. like i said, i sucked up all the solder and layed new beads on all of the pins. before i did this my lights were completely out. when i put it back in they were fine all but for one instance... this is what is confusing me.

Icemark

You need to check the pins in the plug, by removing them from the harness. If they are discolored they are bad. You may or may not have a melted/discolored section of the plastic on the plug with this.
If you didn't get all the old flux out (common problem when re-soldering the clock warning panels) you'll still have a bad joint, even after you flow new solder in.

Also on the headlight switches, if just the dash lights are out, but the parking lights work, often it is because the big transister inside the switch has failed. It fails from being overheating due to bad solder joints.

alexdimen

iTrader: (13)

thanks, i'll check it more thoroughly this sunday. should have been a little more thorough i guess... damn 18 y/o electronics!

Icemark

yeah, some cars (like these BMWs that I have been doing a lot on lately) its not 18 yr old electronics... its 5 year old. Dash displays loosing digits on this with less than 50K miles on them.

jackhild59

iTrader: (7)

So Mark, how do you get the flux out? I have had mixed success resoldering electronics in my 7. I melt the old solder, suck it out with a bulb setup then flow in the new solder. Sometimes it works, sometimes it doesn't. My wiper works, I haven't been successful with the clock.

Am I missing a step or something?

Thanks

Jack

Icemark

I use a expensive de-soldering tool that has vacuum, but a good solder sucker properlly placed should be just fine. You just may have to suck it clean a couple of times

alexdimen

iTrader: (13)

resoldered all the board to harness pins for the second time and checked the harness more closely. the lights flickered on and off again on the highway for a mile or two, but have been fine since then.

when i got the switch panel/guage surround off, i took the light switch module and jiggled the harness, wires, and everything while the lights were on to try and get them to turn off again. i could not cause the lights to go out by doing this.

i have a VDO oil pressure guage spliced into my dimmer wire and grounded to chassis. this couldn't be causing my problems could it? i believe the wire i spliced into is black/yellow stripe. the connection there seems solid and jigglingthis joint around does not cause anything to happen. the guage has been there for half a year...