Headlight switch finicky

[Bishop1911 0]

So tightening up the mach 1 for the wife to drive, snd i noticed for first time other day that i went to turn headlights on, snd i pulled knob, snd nothing.  Several.more tries and nothing.  After 30 to 60 more seconds they came on thanks god then were fine.  Then it happened again.  

 

I am going to get in there today and tomorrow and check it out.  Local oreileys has replacement switches so that's good.  Just not sure if it is switch or not.  

Anyone else have experience with this?  First place to check headlamp switch correct?

 

Thanks

[Mach1 Driver 560]

Unless someone on here recommends O'Reillys, I wouldn't suggest it. The market is flooded with cheap Chinese switches that are junk. Try National Parts Depot, they sell some of the best stuff. The problem could be in several places- the switch, dimmer, firewall connector, connections on the harnesses themselves, or the grounds. This schematic shows how it works, but is not a wire diagram, which shows how it is wired:

[jmlay 80]

I agree one needs to be careful with what is purchased at the local auto parts store. As long as you pay attention to the parts being ordered, filtering out the lesser known, there should be little problems. I this case I believe the switches NPD sells are those from Standard Motor Products, same as O'Reillys lists.

Mike

[Caseyrhe 650]

I have installed 4 or 5 from oreilys, standard was manf, with no issues. 

[danno 128]

As a part of troiubleshooting this, the next time it happens find out if the taillights are working, and if PRDL indicator light is working.   The PRDL shifter indicator light does not use the dimmer, so that will narrow it down.  Do you have brake lights when this happens?  If you do, then you know you a good connection from the battery to the headlight switch, because the power for the brake lights goes through the headlight switch.  Then start doing the jiggle.  Jiggle the connectors on your headlight switch and fusebox at firewall connector.  

Do you have a headlight relay?  A lot of us have installed a headlight relay for brighter headlights.  If you have one, that could be it?  

[Bishop1911 0]

We will be working on the car a bit today tuning it up a little.  We will test this out and see what it does.

 

I dont have the answers to the questions asked about what lights work when they dont turn on because i am inside and never really paid attention. I can say the shifter console light i dont think has ever worked.   There are a bunch of things this car needs, and one thing is for me to strip down the car and redo interior.

 

Will report back on this.

 

Thanks

[Mach1 Driver 560]

1 hour ago, danno said:

As a part of troiubleshooting this, the next time it happens find out if the taillights are working, and if PRDL indicator light is working.   The PRDL shifter indicator light does not use the dimmer, so that will narrow it down.  Do you have brake lights when this happens?  If you do, then you know you a good connection from the battery to the headlight switch, because the power for the brake lights goes through the headlight switch.  Then start doing the jiggle.  Jiggle the connectors on your headlight switch and fusebox at firewall connector.  

Do you have a headlight relay?  A lot of us have installed a headlight relay for brighter headlights.  If you have one, that could be it?  

Danno, I should point out that the PRNDL light does not share circuits with the headlights except for a common connection at terminal B of the light switch. The PRNDL light is on a separate switch contact that runs to light switch terminal R. Granted, the four switch contacts work off the knob, but their function is independent of one another. The only connection the brake lights have to the headlights is also the common connection at terminal B of the light switch. They are on different circuit breakers. So if there is any common problem spot it is at terminal B of the light switch. 

In the interest of keeping the schematics simple and easy to understand, I show the interior and exterior lights on different pages of the schematic. This page for the interior lights will show the rest of the light switch connections:

 

[danno 128]

2 hours ago, Mach1 Driver said:

Danno, I should point out that the PRNDL light does not share circuits with the headlights except for a common connection at terminal B of the light switch. The PRNDL light is on a separate switch contact that runs to light switch terminal R. Granted, the four switch contacts work off the knob, but their function is independent of one another. The only connection the brake lights have to the headlights is also the common connection at terminal B of the light switch. They are on different circuit breakers. So if there is any common problem spot it is at terminal B of the light switch. 

In the interest of keeping the schematics simple and easy to understand, I show the interior and exterior lights on different pages of the schematic. This page for the interior lights will show the rest of the light switch connections:

 

I understand this. If the brake light works, that means the headlight switch is connected and getting 12 volts. If the PRND light works, that also means the switch is getting 12 volts, but it also means the switch is ( at least partially) working. Just using these to narrow it down a bit. 

[Bishop1911 0]

So here is results from test.

 

I turned on headlights, and they didnt come on, but tail lights did.  However we moved snd jiggles stuff and nothing.

After a min or so i tried again and it worked.

 

This seems to be the case.  That always after waiting a min they seem to come on.  Whether i try and flip them on once, or 20 times in first 10 seconds, it doesn't matter..

But after a min or so, they come on when tried again

 

 

I will keep poking around to see what is going on.

[Mach1 Driver 560]

If you have a VOM we can do some real tests, otherwise turn the lights on

1. Does depressing the dimmer do anything?

2. Wiggle the plug on the light switch

3. Wiggle the firewall plug from the engine bay,

4. Wiggle the plug on one of the headlights

5. Wiggle the ground wires where they attach to the chassis.

 

[danno 128]

OK, if both headlights and not the taillights are doing this is can only be the following

1 light switch

2 headlight dimmer switch

3 connection between under dash harness and under hood harness.

Pull up the carpet on the dimmer switch and examine it for a solid or weak connection. 

Mach 1 driver called it Wiggle, I call it Jiggle.  Maybe what you call it depends on where you live or what you are jiggling? 

But I say it now looks like the most likely contributor to this is the headlight switch.   

The simple solution is to be home before sundown.  

[dcm0123 15]

Sometimes the connector goes causing the switch to overheat and fail. Replacing the switch when this happens is a temporary solution unless you replace the mating connector.

If you can get it to work, leave it on for a while then touch the wires coming out of the connector with your hand. If you feel heat, replace the connector as well. Unplug the connector and look for signs of burning on the electrical sockets or plastic inside the connector. This is a sign the connector is bad. If the contact is bad enough, you may not be ale to get the lights to work.

As mentioned above many people buy a relay kit and use the switch to only pull in the relay. The advantage of this is you do not run the high current the headlights requires through the switch. This current is what causes the connector and switch to fail.

[danno 128]

22 hours ago, dcm0123 said:

Sometimes the connector goes causing the switch to overheat and fail. Replacing the switch when this happens is a temporary solution unless you replace the mating connector.

If you can get it to work, leave it on for a while then touch the wires coming out of the connector with your hand. If you feel heat, replace the connector as well. Unplug the connector and look for signs of burning on the electrical sockets or plastic inside the connector. This is a sign the connector is bad. If the contact is bad enough, you may not be ale to get the lights to work.

As mentioned above many people buy a relay kit and use the switch to only pull in the relay. The advantage of this is you do not run the high current the headlights requires through the switch. This current is what causes the connector and switch to fail.

Excellent suggestions. Do the wiggle jiggle while you are sensing if a connector is getting hot.  Midlife can set you up with a new connector if you need it. 

[Midlife 814]

The headlight connector, per se, is not at fault, it is only a phenolic block.  The pins that go into the headlight connector can be suspect, and often times I need to re-crimp the pins to get good continuity to the rest of the wiring system.