Weird ABS vs. LED brake lights?

[mikeinri]

Hi guys,

I have a 1993 RV with a Ford E350 Econoline chassis (G-body?). I know, it's not my Explorer, but I think it shares some parts, and you guys are very helpful!

Anyway, the Rear ABS light is on, and the cruise control doesn't work. I took it to a Ford truck dealer, they think it's caused by the aftermarket LED rear tail lights that I installed.

Has anyone ever heard of this? I found a similar problem that affects Corvettes when I did a Google search.

Is there a fix, other than going back to standard-bulb lights? I put the LEDs in because the rear lights were always pretty dim, even after replacing bulbs and cleaning the contacts with a wire brush. I also think that I threw away the original lights (I replaced the entire assembly on each side).

Thanks.

Mike

 

[mikeinri]

OK, the problem has been confirmed. It's a load issue, apparently the ABS system needs to see a certain amount of load when the brakes are applied or it shuts down the ABS and cruise control.

Now to find a way to fix this without going back to normal bulbs (which would require all new light assemblies again)...

Mike

 

[my pos mounty]

I run into this with aftermarket lights going on Harleys. The computer needs to see the voltage drop when the light illuminates.
I don't know if what is used on motorcycles would work for this application, but the make something like a voltage monitor that will draw the correct amount of voltage to fool the ECM into thinking that the proper light is in working order.
They run about $100.

EDIT: The unit I am talking about is called a "Load Equalizer"
You can check out what they look like/cost HERE

 

[my pos mounty]

You could also do something like splice a regular light socket/bulb inline with your LED's and mounting that somewhere out of the way like in an outdoor storage cabinet or something to that affect. Just keep in mind that they do generate some heat and be careful what is stored around them.
The LED's will not draw enough to screw anything up.

 

[mikeinri]

Thanks.

That sounds about right.

Weird thing was, I would have NEVER made this connection on my own. Cost me $150 for the dealer to trobleshoot and confirm nothing else was wrong. What a weird way to configure ABS/cruise...

I did a Google search earlier today, and found some more info. Apparently, this is a common problem (the lights are Bargman), noted on a few RV forums.

Turns out, there is an aftermarket LED Load Resistor (not made by Bargman) that is sold specifically to deal with this issue. It's pretty inexpensive, and allows me to keep my new LED assemblies.

I'll look into this some more and let you know how I make out.

Mike

 

[nssj2]

you could just solder a resistor inline. That will impede the current to match the voltage drop of a regular bulb. http://led.linear1.org/1led.wiz will walk you through picking out the right resistor. Good luck!

 

[mikeinri]

Quick update, I found an RV store website with load resistors specifically for this application. I've ordered the resistors, should have them installed early next week. I'll let you know how it all works out.

Hopefully, this won't dim the LEDs any...

Mike

 

[mikeinri]

Hey guys,

Well, I finally got around to installing the resistors (better late than never, right?)...

To recap the problem:

New rear LED lights (complete assemblies, replacing stock incandescent), Rear ABS light on, cruise control didn't work, and when the engine was running (with all lights turned off), there was always a faint amount of light generated by the LEDs. None of these symptoms were in place prior to the LED install.

OK, so I installed the resistors, here is the current situation:

Rear ABS light: Not lit (normal)
Cruise control: Works, but cruise cuts out when left turn signal is applied.
LED lights themselves: Work as intended (no faint light when eninge is running and lights are off)

I'm seriously thinking about going back to normal lights, or installing a bulb elsewhere in the circuit as noted by Mounty above.

Mike

 

[Roadrunner777]

Resistor values are close but not right. I might try this: Let's say your current resistor is 50 ohms, 5 watts. Go find a big variable resistor (rheostat, I think they are for power apps) that is twice the resistance and the same wattage. This will let you tweak the resistance until everything works right.

If you want to try this, PM me the current resistance and wattage, and I'll see if I can find you something at radio shack or digikey. I'll be busy the rest of the day, but I'll get you something tonight, if you like.

Otherwise, yeah, just splice in bulbs in parallel to the LED's... cheap bulbs and sockets at oriellys or probably free at the junkyard.

 

[BrianDye]

I just converted to all LED and used these: http://cgi.ebay.com/ebaymotors/LED-...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

I am actually waiting todo my brake lights until I get my new housings, but this should fix your problem. And it doesnt cost 100$ or whatever.

Very easy to wire too, just tap into the brake lead and ground lead.

 

[mikeinri]

The resistors that I have look exactly like that (the ebay link noted above).

Forgot to mention, when I was testing them, they also get really hot.

I like the potentiometer (rheostat) idea...

Mike

 

[BrianDye]

Yea, they do, just make sure you dont have any wires touching them, and use a small screw or 2 to mount them to a metal surface.

 

[mikeinri]

Right now, they are "floating" between the wood of the RV and the plastic of the light fixture... I have a strip of aluminum that I'll use to fabricate some sort of base for them if needed.

I did see some mention of switching the flasher to an electronic flasher, but I'm not sure how that would help the cruise problem.

Mike