Undocumented Saftey Feature - Engine Cuts Out when Brake Controller Fails?? - Diesel Forum

Arizona · 06-11-2005, 02:17 AM

This is scarry. No brakes when engine cuts out. Should say, no power assist when brakes cut out. Almost the same thing if you pulling 10K of trailer.

1999 F350 7.3L Quadcab. Everything has worked for years. No changes made. Last few tow outings were just fine. Trailer is a 5th wheel. Using a standard 7 pin connector. No mods or home brew add ons.

Truck seems to run fine when trailer not plugged in. Can pull trailer with trailer unplugged too (just no Tlights or Tbrakes).

With trailer plugged in, truck will run when transmission is in Park. Step on brake peddle and engine cuts out. Truck can be re-started (without turnign key to off). After a few times the check engine light comes on. Light will reset when key is turned off and then on. Put transmission in Neutral, start engine, put transmission in drive (does not require brake to be depressed to put into drive), truck will tow trailer, but when depressing brake peddle, engine cuts out.

With trailer plugged in, found that with brake controller sensitivity turned down (1.0 or lower), truck will start, tow, and brake normal (engine does not cut out). Don't feel trailer brakes. Turn the brake controller sensitivity up (1.5 or higher) and all the above symptoms of touching the brake peddle and the engine cuts off occur.

Thought it might be the trailer's electric brakes. But they appear to work when applying 12vdc from the battery to the brake lead on the trailer plug (plug is disconnected from truck). Checked all wiring for shorts and grounds. Found nothing wrong. Checked fuses and all was good with voltage. Voltages with and without the trailer plugged in.

Stumpted at this point ... Brake controllers don't generally go bad ... and if they do, they shouldn't cause the engine to cut out. Or is this some type of undocumented saftey feature???

**bugman** · 06-11-2005, 09:39 AM

Your brake controler sends out a RF signal due to the electronics in the controler. This signal interfers with the CPS on the engine. It sounds like you have a weak CPS and need to replace it.

Jim

larry_minn · 06-11-2005, 02:03 PM

There is a ghost in the machine. That is WEIRD. Hopefully bugman's post made sense to you. [img]/ubbthreads/images/graemlins/smile.gif[/img] And that is answer. You need brakes/lights and having truck die wheneve you use brakes is a safety problem. Good luck.

Arizona · 06-12-2005, 03:45 PM

Thanks Bugman. RF intrferring with or masking a weak CPS pulse from sensor to the control module. That could make sense. Truck has 128K miles on factor original CPS. Given failure rate relative to other potentials, that one is a good place to start. If it's not, then I have the spare everyone suggests to keep in the Glove Box along with a 10mm socket, screw driver, and flashlight.

Being a ham, RFI is always something to understand. I'll "tune-in" on that cps lead and look at what signals are making themselves at home and see if I can track it down.

Scarry, a brake controller could shut the truck down.

heinzboy · 06-12-2005, 06:02 PM

[ QUOTE ]
Your brake controler sends out a RF signal due to the electronics in the controler. This signal interfers with the CPS on the engine. It sounds like you have a weak CPS and need to replace it.

Jim

[/ QUOTE ]

Thats alot of Rf to interfer with a brake controller.

MOUNTAINMAN444 · 06-12-2005, 07:17 PM

[ QUOTE ]
[ QUOTE ]
Your brake controler sends out a RF signal due to the electronics in the controler. This signal interfers with the CPS on the engine. It sounds like you have a weak CPS and need to replace it.

Jim

[/ QUOTE ]

Thats alot of Rf to interfer with a brake controller.

[/ QUOTE ]

I knew all electrics and electronics put out some interferance, but I wouldn't have ever thought about it being that much. Makes sense to me though.
Joe

**bugman** · 06-12-2005, 08:13 PM

[ QUOTE ]
[ QUOTE ]
Your brake controler sends out a RF signal due to the electronics in the controler. This signal interfers with the CPS on the engine. It sounds like you have a weak CPS and need to replace it.

Jim

[/ QUOTE ]

Thats alot of Rf to interfer with a brake controller.

[/ QUOTE ] The RF doesn't intefer with the controler but with the CPS. Have you ever been out in the sticks with poor radio reception on the truck radio and when you apply the brakes or activate the controler manually and heard the interference on the radio? It basicily ovrides the electronic signal from the CPS in the same way. A weak CPS can not overcome this interference and the signal is interupted.

Jim

j_apetersen · 06-12-2005, 09:32 PM

It is scarry. It would be nice to know what kind of brake controller we are talking about. mine does not give off RF,

larry_minn · 06-12-2005, 09:53 PM

[ QUOTE ]
It is scarry. It would be nice to know what kind of brake controller we are talking about. mine does not give off RF,

[/ QUOTE ]

As I only know SLIGHTLY what this is all about. (Yrs since I was into anything along this lines) I would guess it DOES give off RF (would bet on it) you just don't realize.
ANYTHING electronic gives off a (slight) RF field. (combs cobwebs in brain) [img]/ubbthreads/images/graemlins/smile.gif[/img] You just can't see/feel/touch/taste it. The example of radio is good.

j_apetersen · 06-12-2005, 10:01 PM

[quote

As I only know SLIGHTLY what this is all about. (Yrs since I was into anything along this lines) I would guess it DOES give off RF (would bet on it) you just don't realize.
ANYTHING electronic gives off a (slight) RF field. (combs cobwebs in brain) [img]/ubbthreads/images/graemlins/smile.gif[/img] You just can't see/feel/touch/taste it. The example of radio is good.

[/ QUOTE ]
So all knowing lts see if you know what you are talking about. and since you said slightly then I am guessing you know nothing. But lets give it a try, what kind of brake controller do I use and sence it does not make radio do anything, does not make truck die. were is the rf,

MOUNTAINMAN444 · 06-12-2005, 10:26 PM

[ QUOTE ]
[quote

...and sence it does not make radio do anything, does not make truck die. were is the rf,

[/ QUOTE ]

I'm not wanting to argue with anyone but here goes. All electronic and electric devices, from cell phones to battery operated tooth brushes and all points in between, give off RF signals. These cause interference to other things in varying degrees. This will depend on the electrical fields and the filtering used on the item. Elecrical and electronic equipment just generate Radio Frequincies and Electrical Fields. Sometimes they interfere with other electronics. They can't help it, it's just the nature of the beast.
Joe

On edit: Almost every thing gives off rf signals. From a piece of steel laying on the ground to the people standing around us. They are just to low to notice. It's just the way magnatism works. [img]/ubbthreads/images/graemlins/warmsmile.gif[/img]

j_apetersen · 06-12-2005, 10:34 PM

so lets get down to the nitty gritty. what does it take to put out rf.A tooth brush is not close to a trailer brake controller, so what does it take to transmitt rf.

MOUNTAINMAN444 · 06-12-2005, 10:40 PM

Almost any thing aroud us which deals with electrical, electronic, or magnetic fields. Some are such small quanities that other equipment isn't interfered with. Sometimes the manufacters filter it out.
Joe [img]/ubbthreads/images/graemlins/warmsmile.gif[/img]

OMCUSNR · 06-12-2005, 10:55 PM

[ QUOTE ]
so what does it take to transmitt rf.

[/ QUOTE ]

What does it take? Any electical source with a wire attached to it. ANYTIME electricty flows, an RF signal is generated. It may be weak or strong depending on voltage, current & resistence. It is a fact of physics. Stand under a high tension wire tranmitting electricty. Hear the HUMMMMM? Thats a RF field being generated.

How do you "protect" against it? Shielding. Wrap the device, wire, powersource, etc with metal or plastic (yep HDPE will shield). If its a minor field, HDPE will work, foil will work (aluminum or tin).

One of the biggest things computer manufacture's have to deal with, using the high speed chips is how to shield them for themselves. They generate High Frequency RF interferance just running, and they have shielding built in.

I know a guy I work with that won't use a cell phone, cause he's worried the RF generated by it will scramble his brains. He may have something there, the way I've seen some drivers using cell phones. Some medical doctors are still out on how badly communications devices affect brain function.

MOUNTAINMAN444 · 06-12-2005, 11:06 PM

[ QUOTE ]
...He may have something there, the way I've seen some drivers using cell phones. Some medical doctors are still out on how badly communications devices affect brain function.

[/ QUOTE ]

Here, Here. Ain't that the truth. And I think they have already fried my brain (what little I had).
Joe