Traffic Lights vs. Jeeps! At Least Mine!!

[bcxjbrisca]

I looked back in previous threads to see if this was ever brought up and didn't see it mentioned. Sorry if I am hashing over something that has been brought up before.

It has started to happen to me in my XJ now and it happens regularly in my JK Ruby 2 dr. I pull up to a controlled intersection and I am the only car going in my direction. My vehicle(s) won't trip the light most of the time!! I often have to "Run The Light" if no other cars come along my way. The only thing I can come up with is "Lifted Vehicle"?? But I thought traffic light sensors worked off of weight/pressure transferred in the pavement near the imbedded wires in the ground. I know that on a lot of lights if you edge just a little too far and your front end is considered to be in the cross walk even a couple of inches it will stop the light from going your way. But this now happening to me in the XJ.

Now the XJ has about 6" of lift and 35's. My JK has 3" and 35's. I have driven many high sitting vehicles at work...none really lifted except for a GM Test Mule Chevy Colorado lifted with Hummer H3 running gear under it. I had no problems. But even the Ford F350 or F450 4x4's I have driven sit with a fair amount of air under them and I have had no problem with them. I mention the Ford because out of the box they seem to sit the highest as the GM's and Dodges I have driven are lower...especially the new 2009 Dodge 4x4's. The Titans & Tundras also are about the same. When I go by a lot of these lights in my cars they work just fine!

So...has anyone ever run into this or have an idea as to what's up?? Even if I back up a few feet and then rerun over the sensors it still won't trip it. OHH WAIT!! I forgot!! It happens with my scooter too..."Scooter" being a Harley. It sits very low but there I thought it was weight. Now I'm really confused!!

:confused1

 

[hiimmred]

Happens to me at a few intersections between San Bruno and San Mateo in both my XJ (4.5" lift) and my motorcycle (83 Interceptor). I think the ones that don't trip do so some other way, it's irritating!!

 

[bcxjbrisca]

Hmmm...maybe it''s a San Mateo County thing 'cause I do most of my own driving on the pennisula. It has happened elsewhere though in my mentioned vehicles but not in any of the work vehicles I drive and that's all over the western United States. Hoping anyone out there familiar with the electronics or operation of these signals can shed some light. Yes...it IS irratateing. I am careful when I proceed through the red light but I just know one of these days a cop is going to see me and he just knows that the signal works just fine...for his cruiser!!:banghead:

 

[99xj4x4]

I think its probably just a jacked up light. Either the sensors bad for that lane or its got a supidly long timer.
Theres a light by my house that I enebitually get in the wrong lane for. the #1 turn lane works fine, the #2 doesnt ever work. I always end up running it. Then there is a weird light at the parking lot of our off road club and it doesnt change for shit, I dont know why, I never wait, i just run it.

 

[bcxjbrisca]

I'd believe it's broken but it works for probably 25 to 30 different cars I drive through it every week and then it doesn't work for my own 2 Jeeps and my bike! And I have driven 3 different factory owned 2008 & 2009 Rubicons (stock) through this light and there's no problem there.

 

[playwithit]

Here's the deal. The loop detectors will only detect a height of two thirds the of the shortest leg in the loop. In other words, if the traffic loop is four by four foot, approx. two foot ten inch is the max height of detection you will receive. Smaller the loop, the less verticle detection will be available

Mass and weight can and will affect detection as well.

The traffic loop uses magnetic flux for detection.

I work with train control (signaling and crossing). Many crossing warning systems utilize exit gates which use loop detectors to keep exit gates raised until vehicles exit the tracks. In addition, we interface with the traffic signals (loops) for preemption.

 

[AJTorris]

Ya i have had the same issue around bakersfield. My wife and i sat at a light here for about 10 min until we decided to make a right turn and then do a uturn and go down the street. it is stupid. The light always turns for us in our dodge ram but in our xj it never does.

 

[fyrfytr1717]

Same problem for me in the XJ and on the Victory. As playwithit alluded to above, it has nothing to do with weight. If you pay attention to the squares cut in the pavement, you will notice they all have a line coming off of them heading towards the light control box. Each "square" consists of a single wire running just under the surface of the pavement. It runs out from the control box, loops around the square a few times, and then heads back to the control box. The loops essentially create an electromagnet and when the control box detects a disruption in the magnetic field it trips the light. I usually try to get my front axle (or my motorcycle tranny) lined up directly above one of the outside edges of the square to improve my chances of tripping the sensor, but sometimes it still won't work.

If you are consistently having trouble with a particular intersection, it most likely means the sensor is getting weak. Call the Public Works department responsible for the intersection and let them know which lane and the direction of travel. They don't know there's a problem unless they get a complaint. I complained about two intersections here in town that would never trip for me. Now I get the green before I even roll to a stop.

If you're really desperate, they make a device for motorcycles that emits a magnetic field for just this purpose. You could probably attach it to the axle on your XJ.

 

[A7XJ]

This is a little off subject but there is a taco bell that i go to and when i go through the drive thru the speaker always messes up and i end up ordering at the window. One guy working at the window says it only does it to Jeeps. I guess I should just take it as a sign to stop eating taco bell.

 

[Letterman]

Yes like posted it is a magnetic field not weight or pressure, hang large skid plates under your rig! :spin3:

 

[bcxjbrisca]

I want to thank everyone for their impute...more than learning on why it happens then opposed to "Am I Frigg'n Crazy or sum'thing?? Am I the only one this happens to??" Glad to know there are others making right turns and then U-turns after and even maybe under pressure...running reds!! It was just weird that it only happened in my own vehicles and since I live a half mile from work I regularly go through one of these same lights with work vehicles to the tone of 25 to 35 times a week and they never have a problem. And the vehicles range from Nissan Versa's to Rolls Royce's to Jeep Rubicon's to who knows what, so I just started to wonder if maybe I was putting out some kind of magnetic field and only when in my own vehicles. Weird but at rest now!! :speepin:

 

[John(XJ)Jeep]

I thought I was going crazy too! But I'd like to ask is this, has anyone been at a light where you are waiting for it to change and then when you finally see the other light change to yellow it goes back green and then forced to wait again? I usually run the light after that irritating event but it has happened quite a few times already. Once it happened 4 times in a row and twice in a row in my buddies truck.

 

[rocknxj]

I've had the same problem at certain lights. Solution is to mount a Yaris on the front bumper.

 

[AirForce_XJ]

I have heard that the Prius works pretty well too.

 

[Ben H]

I wonder if that is why fast food joints never recognize that I'm sitting there in my jeep.

 

[srmitchell]

I have heard that the Prius works pretty well too.

Yeah, the battery really sets it off.

 

[Dustin_Z]

Alright, heres the fix fro your problems guys. I had the same issues with my motorcycle some years ago, and with my Toyota Paseo not too long ago. The traffic loop needs to sense metal...specifically the magnetic fields that are part of it. To make your vehicle "larger" to the lights, go to Radio Shak and get some Rare Earth Magnets. On my bike, I put two of them in small pill bottles (one in each bottle)then attached them to the bottom side of the frame (mag holding it with tie wire as a safety) and on my 'yota I put four loose on the bottom, just stuck them in place. This should help your problem


Or you can just mount an ARB bumper and m8000 to your front ends! :laugh:

 

[fyrfytr1717]

I thought I was going crazy too! But I'd like to ask is this, has anyone been at a light where you are waiting for it to change and then when you finally see the other light change to yellow it goes back green and then forced to wait again? I usually run the light after that irritating event but it has happened quite a few times already. Once it happened 4 times in a row and twice in a row in my buddies truck.

It's just the traffic light sequencing program for that particular intersection. At certain time intervals the light goes yellow and the system checks all the opposing lanes for vehicles. If it doesn't "see" anything, it just switches back to green and starts the cycle over again.

They'll usually program them this way if the intersection has heavy traffic flow in one direction and light traffic flow in the other as a convenience for the majority of vehicles passing through that intersection.