Brake light switch

[john cris]

This morning my 03’ explorer (automatic transmission) would not shift out of park. I’ve had this same problem occur only a couple years ago. So I replaced the brake light switch, again. The original lasted about 190,000 miles, the second less than 10,000 and now the third about 10,000 also. I pulled each switch apart to inspect and found literally no damage. The contacts looked unburned in any way. I tested the switch with a 12vdc source and it cycled properly every time, yet the new switch fixed the problem. What gives? I don’t see any way for the switch to become loose or misaligned that would cause issues. These are mechanical contacts that unless physically damaged will take a lot of abuse before they fail. There was no difference between the Motorcraft or the Duralast or Standard Ignition parts. The problem is solved for now but I’m just curious what else might be at play here.
thanks

 

[Rick]

My thought is that the computer is sensing too much resistance. Put an Ohm meter across the leads and compare the new and old switches.

 

[mountaineer2004]

I know I'm resurrecting an old thread, but that's okay.

The aftermarket products are hit or miss, I think.

My Motorcraft brake light switch lasted for years, and when it went bad my mechanic replaced it with an aftermarket one, saying it's somehow better (forgot exactly why).

That one lasted half the time, and when it went bad again I replaced it myself with the same brand he picked, WVE 1S9220.

Now it went bad again, so I'm replacing it with a different brand, Standard Motor Products SLS 239, hopefully that's the last time I'll need to replace it, as the car has 331k and is losing coolant somewhere unknown nor visible.

 

[J_C]

What did the contacts look like? If not gold plated, or if tarnished, I might have polished up the contacts a little with brasso/etc polish.

Is it possible the switch is working itself loose and you might have been able to just reinstall same switch to solve this?

 

[mountaineer2004]

What did the contacts look like? If not gold plated, or if tarnished, I might have polished up the contacts a little with brasso/etc polish.

Is it possible the switch is working itself loose and you might have been able to just reinstall same switch to solve this?

The switch is cheap and the job is easy to do, so why waste time with defective hardware?

 

[J_C]

The switch is cheap and the job is easy to do, so why waste time with defective hardware?

1) To determine the fault. That can go a long way in determining what to do next. Is it as simple as paying a premium for the motorcraft part instead? Maybe. Maybe not. Motorcraft may have outsourced manufacturing to other than the factory OEM supplier, after all these years.

2) If all these switches are new old stock, with tarnished contacts, cleaning off one to pristine condition, might make it last longer on a 2nd tour of duty than a new one. To clarify I mean clean the internal contacts too.

You imply "waste time", but you might be surprised how often I can refurbish something to about as good as new, and sometimes better than new. It is a hobby of mine to repair things and improve them while I'm at it, so the same fault is less likely to occur again. Granted it is usually something more complex than a mere switch itself.

Plus, it is often that refurbishing something is faster with less equipment downtime, and cheaper.

 

[mountaineer2004]

J_C is correct, I should have tested it beforehand, as it turned out to be the connector that my mechanic originally installed 10 years ago when it first went bad.

When the switch went bad the last time, I simply unplugged the switch, replaced it, and reused the connector. I guess after 10 years something fried in the connector and it went bad.

Even though I saved the new unused connector from last time and could have fixed it in 10 minutes, I'm happy it works now, that's the bottom line to me.

 

[mountaineer2004]

Only now do I investigate. The connector in the top pic is noticeably less snug than the connector in the bottom pic.

I don't know too much about electricity, but maybe tarnishing/oxidation ruined it after a while.

The new connector has an improved design that ensures snugness, so maybe it was a common failure point.

I usually take the easy route, and got screwed this time...oh well, lesson learned.

@J_C

 

[mountaineer2004]

The mystery deepens. I had just finished my brunch at the diner (same as last time), and couldn't shift out of park again. I used the bypass method and changed the switch at home, so now I have a new connector and a new switch, and I'm back on the road.

The switch itself was changed only 7 months ago, so I did some deep thinking (haha) and figured maybe the extra stop lights I had installed about the same time was over-loading the switch itself, so I removed the 2 extra lights (incandescent, so ~ 34 watts more), and we'll see what happens.

I opened up the switch itself to examine it, and noticed the brass contacts had a dark spot, but don't know if this is considered normal. My new thinking now is the aftermarket switches are marginal to begin with, and adding 2 extra stop lights was too much for it.

I added the lights after being rear-ended, but should have picked the LED ones on the next hook at the store. I replaced the extra lights with a reflector.