BD Exhaust Brake - I'm puzzled about sticking relay.

[Killgore]

Several threads were started lately concerning exhaust brakes (operation, installation, etc.) and my question wouldn't fit in either without hijacking the threads. So, let me ask this under its' own heading: Has anyone experienced a problem with the five-prong 40amp relay sticking and if so, how did you fix it? Occasionally, every other day or so, the 1"X1" relay will stick closed and the compressor will continue to run even after shutting off the engine. A simple tap on the top of the relay with my pocket knife will cause it to release. I have searched high and low for a negative ground leak, replaced the relay several times, and continue to see the issue arise on an inconsistent basis. Help?
- Ed

 

[Prairie Dog]

Yes, I have had mine stick. I got the number off it and replaced it with one from NAPA.
I feel that it was cooked by its location on top of the eng. So I moved mine to a cooler location - no problems since.

Scott

 

[mwilson]

After replacing the relay is there a temporary improvement??? Wondering if the compressor is getting shakey and it's drawing enough to roughen up the contacts in the relay when it engages. Then the relay gets sticky from the arc spots.

 

[Killgore]

Yes, Mike. It appears to run for several weeks without sticking after replacing the relay with a new one. The compressor is less than a year old. Now that I think about it there appears to be some correlation between hot days, heavy stop and go traffic, and sticking. The relay, regulator, etc. are all mounted on the firewall, exposed to some heat. I've thought at times that the small spring in the relay just wasn't strong enough to return the points to the open position when the magnet was deactivated, or perhaps there is a small residual charge still on the magnet. With cold weather fixing to hammer us this weekend I may not have any additional sticking for awhile.
- Ed

 

[mwilson]

Prairie Dog's relocation idea may help, or a bigger relay. Maybe a combination of both.

I know that there are 12V relays with a higher amp rating. I think? 40, even 50. Thermo King may have a larger one than that. Home now so can't run down an aisle and look.....

 

[jelag]

We installed pacbrake for 20 years and installed lot of relays close to the intake manifold with no problems I'm aware of.. I personally buy relays and their sockets from delcity.net.. I use them for relays, connectors, shrink tubing with adhesive in the tube... and all kinds of things... I personally would get a new relay...

 

[Killgore]

Good advice from all of you, and thanks. I ordered a Bosch 60A 5-prong relay today and will be surprised if that doesn't solve the problem.
- Ed

 

[p-Bar]

Sounds like a capacitor across the contacts would stop a lot of arcing and possibly sticking. I'm getting ready to install EB in my truck . Wondering why they go to a solenoid?

 

[Killgore]

p-Bar, I'm not much of an electrician as you probably can tell and up to this point my understanding is very elemental. That being said, I am aware that the compressor is pulling some kind of power because the headlights will slightly dim when it cycles. Is this normal? If problems persist after replacing the 40A relay with the 60A that I just ordered, I will either seek to replace the compressor under warranty or spring for an on-board air system with a compressor and tank large enough to air up my tires and support an impact wrench.
- Ed

 

[p-Bar]

Ed , I just purchased the complete BD EB with compressor . I pulled the compressor out of the box and it says max 20 amp. I would put an amp meter on it and see how much it is drawing just to make sure it isn't the motor going bad. I had bought a larger compressor which I am wanting to do on board air with a tank too. but I know this down the road and I want to get this unit on for my Christmas trip to Texas. Good Luck

 

[BD-Hector]

Also check the relay socket/holder, inspect the plug portion for any signs of corrosion. the 2006 is triggered by a ground signal so ig you have a short to ground anywhere this will also cause your issue. check the harness that is running through the firewall for chaffing.

 

[Killgore]

Hey there, Hector. I've looked from one end to the other without finding anything amiss. I've got the 30A fuse in the line and it hasn't blown at anytime. It's a real head scratcher.
- Ed

 

[Deleted member 995608]

I that's pretty cool that Hector chimed in. Can't ask for better service than this.

 

[Killgore]

Hector, Cam and Mark have always been very accommodating when I've had installation questions or a service issue. Service after the sale is very important and they do an outstanding job.

 

[BD-Hector]

Ed, I'm glad the guys have been working with you. This is really an odd situation, the next time it happens will you cut the relay open the bottom and send me photos (or send me the relay I would like to cut it open and see what might be going on.) What happens if you use the toggle switch off and on quickly? As a test to rule out the ECM, being a ground feed we can connect the tan wire running through the firewall (pin 39) to the black ECM to relay wire (pin 42). keep in mind the exhaust brake will no longer shut off with the throttle, but if it acts up again bypassed from the ECM we can quickly check the harness and then look at the mounting location of the relay or possibly a different relay supplier.

 

[Killgore]

Thanks, Hector. The 40A relay I'm running now has been on about three days with no issues. The one it replaced got thrown about a country mile into the woods, otherwise I would have sent it to you, lol. If this one starts to stick I'll send it to you though. I did receive a 60A relay in the mail today that is being held as my backup pending a trip to South Texas in a week or two.

Flipping old rattler on the stick off and on doesn't cause the relay to release which would have been an easy fix. I think I'm mystified. I will isolate the ECM as a last resort.
- Ed

 

[Prairie Dog]

If your headlights are dimming with the compressor cycling then you have a poor connection someplace. That is a definite sign that something is wrong.

 

[Killgore]

Prairie Dog, I see just a little dimming as the compressor cycles. I thought something didn't add up though. I've cleaned battery posts and connections, but will go over it again in the morning. I need to borrow somebody's amp-meter that will register more than mine.

 

[Prairie Dog]

So if I understand correctly, the EB stays on even though you put your foot on the throttle - right?
When this happens, can you pull the relay and make the EB turn off?

Scott

 

[Killgore]

No, actually there is a slight hum from the relay/compressor (hard to tell which because of all the racket coming out of the engine compartment) that is unaffected by throttle or switch, but the EB continues to operate normally. When I turn off the ignition the compressor starts to run. Pulling the relay or just tapping on it will shut the compressor down. I've taken several relays apart, removing the cover, and used the relay with the cover off observing that when this condition results, the points are open as if the magnet is being energized or at least the switch is not returning to where the points close. This would of course be indicative of a negative ground leak. I have broken the contact with the magnet by just barely touching the points. Hmmm...is the spring heavy enough to return the points to a closed position? Is the relay just worn out after so many cycles, meaning it needs to be a heavy duty item? All this leads back, assuming the harness is okay, to putting the 60A relay on and probably fixing the issue. Thanks, Scott.
- Ed