headlight sensor - how to disconnect?

[Dreamin]

Has anyone disconnected the sensor for their headlights?

My Vette has decided to turn the headlights on/off whenever she feels like it. It's normal operation when I first start her but once we are up and running, the headlights come up and will either go up/down randomly in broad daylight with full sun or the headlights won't go down until I turn her off.

This has happened before but it seemed to go away by simply using a can of pressurized air to blow any dust out of the sensor on the dash. That doesn't seem to work anymore.

Apparently I can disconnect (or override) the sensor to manually operate the lights.

So, if you have disconnected your sensor, how did you do it? I've read through our Haynes manual but I couldn't find anything useful in it.

Thanks in advance.

Ann

 

[JonM]

Submitter's Name: Doug Hornok

The credit for this tip really belongs to FrankD.

I was getting annoyed with my headlights constantly flipping on and off on my c4 every time i drove through the shade. My car was originally a Canadian car, and had no way to shut this feature off.

To disable the lights, carefully pull the light sensor located directly above the speedometer out of the dash to expose the 2 wires running in to it. Place a 100 ohm resistor in parallel with the sensor. Tape it up and stick the sensor back in the dash. You will now have complete control of when your headlights turn on and off.

 

[Dreamin]

Thank you for passing along the tip. Do you mean to tell me it's only the Canadian cars that have this feature?

Disabling the sensor as you suggest will be my tomorrow project. Like you said, I'm getting sick and tired of the constant flipping.

Cheers.

Ann

 

[JonM]

Thank you for passing along the tip. Do you mean to tell me it's only the Canadian cars that have this feature?

Cheers.

Ann

Yep....only in the

Cars

 

[greydbj]

Check out this website, you will find exactly what you need....invented by a Canadian for C4 owners.....I have a C3, but he is a fellow Capital Corvette Club member and more than a few of our colleagues, Canadian and US have one of his devices.....if you go to Carlisle, he will be there, but you can order from the website......

http://www.corvettegadgetman.com/

Regards....dbj

 

[Dreamin]

JonM - now I feel really stupid! I haven't pulled the sensor off the dash yet because I'm having trouble finding the resistor. Who knew that would be such a problem. Anyway, I'll find one today if it's the last thing I do (today, anyway).

Question: Your instructions on locating and removing the sensor are clear as a whistle. It's after that I get brain dead. Does the resistor get wired in? If that's the case, then should I be looking for a resistor that's already wired? Your help would be appreciated. If you could pretend you are explaining this to a kindergartener, that would work great!

greydbj - thanks for the link. I'm looking at the vent that my husband has been wanting for a while. I had heard of the gadgetman and that his solution works pretty well. I'll see if I can do JonM's suggestion first (to save a few bucks, the days wait for product delivery and because I don't give my credit information over the net....). But I may have to resort to the gadget. Thank you.

Ann

 

[Dreamin]

O.K. Found a 113 ohm resistor. Does an extra 13 ohm make a difference?

 

[JonM]

Sorry Ann for the delay...I was out back painting the tool shed...Yes you do have to cut the wire and place the resistor in line. I also did another search and came up with a simpler fix...
--------------------------------
I had the same problem of the lights popping up... the simple fix pry up the sensor from the dash, there will be two wires. I cut both wires and then taped the ends with electrical tape. Then I taped the wires all together ( ie back with the sensor ) so that the wires would not fall ounder the dash... instant success.. the lights will not put up by them selves, they are now controlled by your light switch... I did try cutting only one wire, but didn't work.. once both wires were cut( ie the circuit was cut) it worked like a charm... no need to do anything else..
--------------------------------

I found the above at the http://www.40thregistry.com

I am not an electronics expert so the extra resistance I wouldn't know about. Hopefully an electronic guru will chime in.

Here is a hint...if you are going to cut the wires to the sensor...tie a 3-4 fot string on them in case they fall back into the hole.

 

[Dreamin]

JonM - hopefully you appreciated the distraction from painting, unless you are like me and it could take days (months) to get back and finish the project! )

How did you find this information by searching? I always search too before popping a question (hate to look stupid as it comes naturally to me).

Anyway, thank you, thank you, thank you.

Ann

P.S. I did think about putting clamps on the wires as it did occur to me they might accidentally fall back inside and then I'd really be hooped.

 

[JonM]

JonM - hopefully you appreciated the distraction from painting, unless you are like me and it could take days (months) to get back and finish the project! )



How did you find this information by searching? I always search too before popping a question (hate to look stupid as it comes naturally to me).

I finished the job before I came back in...I am the opposite of you, I need to finish ASAP any project I start.


Yes, I did a search with a few directives..ie Disable Automatic Headlights, Disable the Twilight Sentinel


Let us know how you made out, maybe you could write a TEch Tip and give it to Rob to post in the knowledgebase.

 

[Dreamin]

BRILLIANT!!!! The job is done. JonM, you are an angel and a saint.

It took minutes and was so incredibly simple. If someone really wants this in the techtip, maybe this can be cut and pasted. I will use some of your words as you describe things very well.

You will need electricians tape, sharp scissors (and wire cutters too if you have them) and vice grips (to hold the wires in place while you work).

Carefully pull the light sensor located directly above the speedometer out of the dash to expose the 2 wires running in to it. The sensor has pressure clips to hold it in place. I pulled the sensor up as far as I could and then used a letter opener to push the clips in on one side to release the sensor.

Pull the sensor out as far as you can to give you lots of wire length to work with. Clamp the wires to hold them in place against the dash or the wires will fall back in when they are cut.

Do one wire at a time. I didn't cut the wires too close to the sensor just in case another owner wanted this feature and would have to splice the wires back together.

Cut one wire and tape off both ends - you want to make sure that when you tape them together there are no bare ends touching each other. Tape the two ends back together leaving a space - remember, you don't want bare wires making a connection. Repeat the procedure for the other wire.

For neatness, I cut the wires in different places to reduce bulk, e.g. make the cut on the second wire about an inch away from the first wire. Then, I taped the wires together to make sure they could be pulled out again in future.

Before putting everything back, start car and feel along wires to make sure there are no hot spots. Put everything back and.....WALLAH!.......you are now fully in control of your lights.

Imagine that....our Canadian government thinks we are too stupid to turn on our lights when the sun goes down!

Ann

 

[JonM]

BRILLIANT!!!! The job is done. JonM, you are an angel and a saint.
Ann

Out of 6351959817 people in the world...who would have thought I would run into that one person here on CAC that really knows me.

 

[Dreamin]

THE THEORY IS FLAWED!!!!! I discovered this as soon as I took the parking brake off.

In retrospect, how could simply cutting the two wires work? There must be a missing step..... I guess that's where the resistor comes in. Do the sensor wires get attached to each end of the resistor?

Here's my thinking.

The sensor is designed so that when daylight reduces to a certain level the sensor triggers the system to tell the vehicle to turn the lights on. When the sensor receives enough light (as in exiting a tunnel), it sends another signal to turn the lights off.

So by cutting the wires and disconnecting the sensor it would be the same as putting tape over the sensor - darkness all the time = lights on all the time. The sensor no longer receives the "enough light" message. The default setting is no light. Light is required by the sensor to turn the lights off.

Where, oh where, did I go wrong? Should I have actually joined the two wires together or would that have shorted the system?

Suggestions anyone?

Ann

 

[JonM]

Ann...I would try one of these scenarios before you try connecting the wires togther.

Don't you have an equivilant of a Radio Shack up there? They should be able to help you with the resistors.

 

[Dreamin]

We have a Radio Shack up here but they don't carry this size resistor. Hubby and I hit the phone book and called Radio Shack, Rona/Revy, Canadian Tire, Lordco, a few others and then finally BeamRiders. BeamRiders said they had one for two bucks Canadian. Hubby went down to get it and they discovered it was a 1000 ohm, not 100 ohm. Would you believe they actually built me a unit - took two hours - final cost eight bucks Canadian. It measures 103 ohms and is huge. I'm going to take a photo of it in case no one believes me. I figure I can get the unit through the hole but I'm going to make sure it works first. I may never get it out (easily).

Anyway, JonM, if you are there......do I simply splice one end of each connecting wire to each end of the resistor (now actually 3 resistors in units joined together in parallel with two free wires)? The wires I would be splicing to the resistor would be the ones running out of the dash (the sensor is completely remoted), then tape the unit to the sensor and push it all back it?

Your help is VERY much appreciated. Thank you also for perserving and taking so much time with this. As you can tell, I'm not an electrician.

Hope to hear from you.

Ann

 

[JonM]

Did you click on the pic I drew for you below? Its pretty self explanitory...There are three different scenarios. If you want, I can check the stores down here and mail you the resistors.

 

[Dreamin]

No pic (that I could find). Anyway......I DID IT!!!!

I'm going to take some photos now just in case anyone else ever asks the question and need to see exactly what they are dealing with. The only thing unusual about the pics will be the resistor.

And, it really does work - I took the car for a drive. Headlamps are completely manually operated now. Yeah!!!!! No More Flippin' Headlights!

JohM, again, thank you, thank you, thank you. Your offer to get the part for me is really very sweet. As before, you are a saint and an angel (and I truly am the only person in the whole wide world that really knows you! - GRIN!!!!). I am so thrilled I could find more wonderful words for you but we wouldn't want all this to go to your head now, would we?

Ann

 

[Dreamin]

JonM - Oops! My apologies....I found the pic. Geez I wish I had been smart enough to notice that before. You mean I only had to cut one wire?

Well, at least the next person who tries this will have a successful first go.

Ann

 

[JonM]

I'm glad you got it working...Twice ...post the pics. Which scenario out of the three pics did you use?


I have a Canadian Fan yeee haaa...Don't tell hubby about out electronics affair...tell him you did it all on your own.

 

[Dreamin]

I guess it would be the first scenario.

Too late. hubby already knows I had a mentor.

I'm still going to look for a nice simple 100 ohm resistor and will replace the unit I have in now. That gave me all sorts of installation problems and I am worried that I may have caused a whole new set of problems. Car seems OK though. As I was trying to get the wiring and sensor back in place my son said "did you pull the airbag fuse?". And, careful while you are pushing that thing back down...you might hit something and trigger the airbag or something else... As you can guess, my imagination has started to run away. (Haven't made my Will yet).

Anyway, here's some photos. Forgive me if this doesn't work - it's the first time I've ever posted photos before. Maybe you can teach an old dog new tricks?