Robert Rausch

My Pacbrake hasn't worked in awhile so today I decided to troubleshoot it. I can make the Pacbrake engage and disengage manually by removing the solenoid and pushing on the little vacuum valve, and I can engage it by pushing on the end of the solenoid when the solenoid is connected to the vacuum valve. I have 12+ to the solenoid when the key is on, and the Pacbrake switch is thrown. So it seems like the solenoid won't engage. Is there a trick to cleaning these? I've cleaned mine before, and it generally got it working again. Or are these solenoids a weak point?

infidel

See if this helps http://pacbrake.com/PDF/L5223.PDF
The solenoids are a high maintenance item.
Seems like somehow exhaust soot works it's way back into the solenoid.
One thing I like about Pac is their excellent customer service. If you can't fix a problem they always send you new, often updated parts for free.

Robert Rausch

THAT'S what I've been looking for. That's the way I used to do it, but had lost the instructions, and I couldn't seem to figure them out on my own. Thanks Bill.

rebal

make sure your micro switch at the go pedal is not bad or maladjusted it will keep the solenoid from working too

Robert Rausch

What microswitch? A Pacbrake-specific m-switch, or something factory?

infidel

PacBrake switch.
Should be on the throttle linkage near the injection pump.
Keeps the butterfly open except at idle.

runningbird

or it could be mounted near the accelorator pedal.

Robert Rausch

OK. It's a bad solenoid. Everything else checks out fine. I can engage and disengage the Pacbrake manually by pushing the button on the end of the solenoid, but when I disconnected the solenoid, and hit the switch with the key on, it wouldn't operate at all, even though it is getting 12V+ just fine. I guess first thing Monday I'll call Pacbrake and order a new one. Thanks guys for the input.

Robert Rausch

Expensive little bugger--over $90 for that solenoid!

infidel

When I've talked to the fix it tech at Pac he's sent me parts, including the solenoid for free.
The parts guy there charges...

Robert Rausch

Damm. My Pacbrake is over 10 years old--it never occurred to me that they'd give me one.

Robert Rausch

Update: I put in a new solenoid, and got a replacement cylinder. And I have good news and bad news. Good news is it works. Bad news is it only works sometimes! So I traced that problem to the microswitch on the front of the pump. It only works when I press the fuel linkage against it and make it press the microswitch inwards. Adjustment you say? No amount of adjustment seems to work. Too far out and the truck idles at 1,000 rpm. If I move the switch backwards the idle goes back down, but there doesn't seem to be enough pressure to push the microwitch in and engage the Pacbrake. If I manually push the fuel linkage against the microswitch the Pacbrake will engage.

So my question is... is it possible a return spring of some sort came off my fuel linkage and therefore there's not enough pressure to push the microswitch inwards? I took the microswitch off and sprayed a little 100% silicone spray in under the boot and replaced it. Still no workie. Ideas?

infidel

Some have two return springs, mine have one inside the other.


The micro switch is a common Radio Shack item, less than $10

Robert Rausch

Thanks Bill for the diagram. I'll check tomorrow.

Robert Rausch

Bingo--it was broken. Mopar4Less wanted $4 and some change, but didn't have it in stock. Local Dodge dealer in L.A. (I'm out here on a job) wanted $7 but didn't have it in stock either. I'll get it and hopefully that'll get my PacBrake going again.