No Headlights

[Rich_NYS]

I'm beginning to troubleshoot my no-headlights condition.

I'm using a voltage-tester at the headlight sockets and have no voltage.

There is no voltage at fuse 14, but there is voltage at the low-beam relay socket. I have very little relay-troubleshooting experience, but I tested the socket for voltage & grounds. There was voltage on one of the terminals, but continuity to ground on all others....that seems odd to me, is it normal or an indication of trouble?

I also pulled the plug off the headlight switch to prepare for testing there; I haven't tested anything yet, but took this pic:

27308

Does that appear normal? I don't know what the thing is that's "half-tapped" onto the Blue and Blue/Brown.

I'll be working on it again tomorrow using the schematic, a voltage tester, and VOM.


Also, what is a "dip-beam?"

Thanks!

[David T]

I'm beginning to troubleshoot my no-headlights condition.

I'm using a voltage-tester at the headlight sockets and have no voltage.

There is no voltage at fuse 14, but there is voltage at the low-beam relay socket. I have very little relay-troubleshooting experience, but I tested the socket for voltage & grounds. There was voltage on one of the terminals, but continuity to ground on all others....that seems odd to me, is it normal or an indication of trouble?

I also pulled the plug off the headlight switch to prepare for testing there; I haven't tested anything yet, but took this pic:

27308

Does that appear normal? I don't know what the thing is that's "half-tapped" onto the Blue and Blue/Brown.

I'll be working on it again tomorrow using the schematic, a voltage tester, and VOM.


Also, what is a "dip-beam?"

Thanks!
Do you hear any relays click when you try to turn on the headlights? The most common causes of no headlights is:
1) a melted headlight switch
2) burnt out headlight filiments

The "Dip" is when you pull the high/low switch and momentarily lower (or raise) the high beams. The high beam switch is also known as the dip switch.

[NightFlyer]

Does that appear normal? I don't know what the thing is that's "half-tapped" onto the Blue and Blue/Brown.

I don't know what that's for either, but I can provide a speculation - an override to flash the lights without switch activation when the alarm (that you uninstalled) was activated???

I'm not very good at trouble shooting electrical problems...

[Rich_NYS]

Do you hear any relays click when you try to turn on the headlights? The most common causes of no headlights is:
1) a melted headlight switch
2) burnt out headlight filiments

The "Dip" is when you pull the high/low switch and momentarily lower (or raise) the high beams. The high beam switch is also known as the dip switch.

Thanks David,

I don't hear the relay when I turn on the headlights, but I do hear one when I hit the high-beams. What do you think of the continuity-to-ground I'm seeing on all terminals (but one) at the relay socket?

Tomorrow I'll test the headlight plug for voltage to confirm/deny the headlight switch....would be great if that's all it is. :thumbup:



I don't know what that's for either, but I can provide a speculation - an override to flash the lights without switch activation when the alarm (that you uninstalled) was activated???

I'm not very good at trouble shooting electrical problems...

That seems like a pretty good guess, those red taps aren't factory, right? I kinda want to remove that thing, even not knowing what it is because it feels like it doesn't belong there. :hmm:

[DSNW Toby]

I'm beginning to troubleshoot my no-headlights condition.


I also pulled the plug off the headlight switch to prepare for testing there; I haven't tested anything yet, but took this pic:

27308

Does that appear normal? I don't know what the thing is that's "half-tapped" onto the Blue and Blue/Brown.

Also, what is a "dip-beam?"

Thanks!

I would guess that somebody has inserted a condenser in there to attempt to reduce arcing in the switch. It is not a normal installation. The "dip beam" is British terminology for the low beams. The fuse is located between the relay output and the headlight socket. You shouldn't see a voltage at the fuse unless the relay is triggered and is passing current to the lights. 4 pins are used in the 5-pin relay socket. Brown wire is battery positive. Black is ground. Blue/purple is the relay trigger from the left hand stalk "dimmer switch". Blue/red is output to fuse #14 and ultimately to the light socket.

[AugustneverEnds]

Hey fellow New York DMCer!

Have you checked the relays? Sometimes when you pull them out and re-insert them the ground gets pushed out and no more headlights! I did that last summer and spent a week troubleshooting only to find it was the ground

[Rich_NYS]

I think everything's OK at the relay; I have continuity to ground in the relay socket.

I have voltage at the headlight switch and I'd like to "jump" something to confirm/deny the switch. Would sending the feed [at the headlight plug] to the blue wire do it? That would hit the blue/purple relay trigger, right?

[Rich_NYS]

I took out the headlight switch & tested it with a VOM, it didn't seem to be doing what I'd expect so I went ahead & jumped the B/U to the U at the plug and good things happened.

It appears to be the headlight switch, but too soon to know if it's melted.....I'm goin' in!

[Rich_NYS]

Yup....it's the switch.

I saw some posts mentioning a mod to prevent this, but it also looks to me like it wouldn't be too hard to fix this for now. Anybody got a pic of what it's supposed to look like prior to melting? Seems like all I'd need to do is insulate the contact in the right place.

I also read the mod is designed to lower the amount of current through the switch, but converting to LED's accomplishes that as well. What's the "latest & greatest" on where to go from here?

Thanks everyone for the responses...very helpful! :thumbup:

[NightFlyer]

Yup....it's the switch.

I saw some posts mentioning a mod to prevent this, but it also looks to me like it wouldn't be too hard to fix this for now. Anybody got a pic of what it's supposed to look like prior to melting? Seems like all I'd need to do is insulate the contact in the right place.

I also read the mod is designed to lower the amount of current through the switch, but converting to LED's accomplishes that as well. What's the "latest & greatest" on where to go from here?

Thanks everyone for the responses...very helpful! :thumbup:

The MLS switch saver mod offloads a majority of the current to being handled by a relay as opposed to the switch.

The improved/redesigned switch that DMCH (and franchisees) sells offloads all the current to external relays, thus relegating the switch to a mere trigger.

Or, as you already stated, you can switch a majority of the lights operated by the switch to LED, which will greatly reduce the amount of current carried through the switch, which will greatly reduce that amount of heat generated at the switch.

Here's a pretty good thread to take a look at:

dmctalk.org/showthread.php?6047-Scary-headlights-died-at-night

Glad that was an easy find and fix :thumbup:

[Rich]

....looks to me like it wouldn't be too hard to fix this for now. Anybody got a pic of what it's supposed to look like prior to melting? Seems like all I'd need to do is insulate the contact in the right place.

I also read the mod is designed to lower the amount of current through the switch, but converting to LED's accomplishes that as well. What's the "latest & greatest" on where to go from here?

You ask for a picture.
In this photo John Hervey shows a "melted switch":
LINK: http://www.specialtauto.com....headlight-switch-melted.jpg (http://www.specialtauto.com/delorean-parts/images/headlight-switch-melted.jpg)

The far prong is the melted one - the brass contact got so hot it melted/deformed the nylon that supports it - and the near prong is what the far one used to look like.

His webpage says he can fix it if it is melted.

Getting the switch apart is a bit tricky. Getting it back together is somewhat trickier. And that is with an unmelted one that switched OK (I needed to replace the lamp inside it once).

FWIW I've been running a switch-saver relay for a long time. Works great.

[Rich_NYS]

Thanks Rich, I was able to fix the switch. I got pretty lucky, I just needed to remove some melted nylon to normalize it a bit:

27331 27332

I might get that relay setup, but thinking I'll just convert the sidemarkers to LED's for now and see how it goes.

[Rich]

Nice work, Rich!

If you cleaned the contacts up and everything is straight inside there then it will probably last long enough for you to reduce the load either via the LEDs or the relay. Or maybe longer.....

Anything that lights up with the first switch position is part of that load. The load on that formerly-melted contact remains the same in the headlight position because the other contact controls the HL switching and that switching current is handled via......relays downstream of the HL switch.

-Rich

[Ron]

The MLS switch saver mod offloads a majority of the current to being handled by a relay as opposed to the switch.$.02
The Main and Dip Beam relays are wired directly to the battery and headlight bulbs (unfused). Only the current for their trigger(s) go through the MLS (very little, then ~insignificant).
(The small bulbs (markers, cigar, clock, etc) are fed through the MLS, but no big deal, barring shorts. I'd spend the money on LEDs instead because they are easy on the alternator/battery...and just cool ;-)

[David T]

$.02
The Main and Dip Beam relays are wired directly to the battery and headlight bulbs (unfused). Only the current for their trigger(s) go through the MLS (very little, then ~insignificant).
(The small bulbs (markers, cigar, clock, etc) are fed through the MLS, but no big deal, barring shorts. I'd spend the money on LEDs instead because they are easy on the alternator/battery...and just cool ;-)

I think the main reason the headlight switch melts is because of corrosion in the front side marker lights. That creates a higher current and since it goes through the switch it gets melted. Can happen even with LED's. The best advice is to get one of the switch saver relay setups. The headlight switches are getting rare and expensive. You can get by cleaning it up inside only so many times.

[Bitsyncmaster]

I think the main reason the headlight switch melts is because of corrosion in the front side marker lights. That creates a higher current and since it goes through the switch it gets melted. Can happen even with LED's. The best advice is to get one of the switch saver relay setups. The headlight switches are getting rare and expensive. You can get by cleaning it up inside only so many times.

I don't believe corrosion at the light sockets would increase power draw any significant amount.

[Ron]

I think the main reason the headlight switch melts is because of corrosion in the front side marker lights. That creates a higher current and since it goes through the switch it gets melted. Can happen even with LED's. The best advice is to get one of the switch saver relay setups. The headlight switches are getting rare and expensive. You can get by cleaning it up inside only so many times.$.02
I'd just replace the bulb sockets if they were that bad -- If concerned about the switch, install a simple inline fuse along the RO wire.