Pacbrake PRXB

[jhenderson]

Is anyone running the ECM or throttle bypass wiring and if so why? I'm planning on replacing my Jake and I'm leaning towards Pacbrake PRXB but I'd like some input on the options. Thanks.

 

[Prairie Dog]

Mine is hooked into the PCM. It was easy to do and works perfectly.

 

[Shadrach]

It works great, and you get air for other things. The bypass is not needed IMHO. With it plugged into the ECM it will kick on when going downhill when the brake and cruise are both turned on. If you like to gain speed when going down to get momentum for going up, just turn the brake off. With the switch mounted on the stick it is easy to activate at will. I recommend you get the 100% duty cycle air compressor.

David

 

[AEdelheit]

Ive had one on my G56 equipped 06 and now on my 48RE equipped, Both work great and go through the ECM, on the G56 truck I did install a clutch switch so It did not engage every time I shifted, that got old. The warm up feature is great and the only downside on the 48RE truck is it cuts off at 25mph and from what I understand It has more to do with the transmission not being able to lock up in 1st.

 

[Prairie Dog]

Ive had one on my G56 equipped 06 and now on my 48RE equipped, Both work great and go through the ECM, on the G56 truck I did install a clutch switch so It did not engage every time I shifted, that got old. The warm up feature is great and the only downside on the 48RE truck is it cuts off at 25mph and from what I understand It has more to do with the transmission not being able to lock up in 1st.

The ECM gives a 2 second delay so you can shift so that should not be an issue.
Works perfectly on mine.

 

[AEdelheit]

Actually it does not, neither of my trucks have a 2 second delay, I can assure you it was an issue as I drove for a few months before doing the clutch switch. I didn't think the 2003s had exhaust brake function through the ECM, do you have a separate controller on yours or does it go though the ECM?

 

[Prairie Dog]

Actually it does not, neither of my trucks have a 2 second delay, I can assure you it was an issue as I drove for a few months before doing the clutch switch. I didn't think the 2003s had exhaust brake function through the ECM, do you have a separate controller on yours or does it go though the ECM?

That's interesting. I remember reading where some trucks didn't work quite right with an EB connected to the ECM because the APPS never went to zero or some such issue.
At any rate, yes, not only does my ECM support EB function it also can throw codes because of it. One time I had a relay in the EB circuit fail and it actually stored a code - "EB circuit stuck low" or something close to that.
Glad you got yours sorted out despite the ECM not playing along.

 

[Tuesdak]

What's wrong with the Jake that you are replacing it?

I can't shift the NV5600 fast enough to keep the brake off between shifts so I just blip the throttle. Well, it doesn't like being shifted fast anyway...

Mine is run through the ECM and works well shutting it down when on.

 

[jhenderson]

380,000 miles of use. 4 vac chambers, 1 relay, now it needs another vac chamber and the the vac switch ( electrical coil) is giving me grief. Parts, other than the vac pump are expensive and hard to get. When I replaced the relay, Jacobs wanted to sell me the entire wiring harness. Had to search the Internet for the correct weatherproof part. Wasn't an easy get. The butterfly is worn in the cast elbow and doesn't provide full back pressure any more. I think it has exceeded its projected lifespan.

 

[AEdelheit]

That's interesting. I remember reading where some trucks didn't work quite right with an EB connected to the ECM because the APPS never went to zero or some such issue.
At any rate, yes, not only does my ECM support EB function it also can throw codes because of it. One time I had a relay in the EB circuit fail and it actually stored a code - "EB circuit stuck low" or something close to that.
Glad you got yours sorted out despite the ECM not playing along.

Ya there is maybe a 1/2 sec delay if even between taking my foot off the throttle to the exhaust brake engaging, at least for me every 06 Ive driven with an exhaust brake, 4 of them, have been that way. Dont know if mine will store codes or not as Ive have not had any issues yet with them luckily!

 

[seafish]

AFAIK, the ecm delay is there to allow rail pressure to drain just in case you remove your foot from DEEP in the throttle with the EB on, the EB , sensing TPS of 0, does not immediately engage while rpm is till high (i.e. while the fuel rail pressure is still draining) thus protecting the engine/valves from excessive back pressure.

 

[AEdelheit]

So the ECM varies engagement time based on engine RPM up to 2 seconds? That would make sense, I know driving around town light throttle there is very little delay, dont usually run full throttle with the exhaust brake on.

 

[seafish]

So the ECM varies engagement time based on engine RPM up to 2 seconds? That would make sense, I know driving around town light throttle there is very little delay, dont usually run full throttle with the exhaust brake on.

Do NOT know for sure, but I believe that might be the case…. I've heard varying opinions as to what the ECM induced delay actually is and I am guessing that it has to do with preventing excessive back pressure on the engine/ exhaust valves. And while most people like you likely do NOT drive in high throttle situations with the EB on, those situations can and do exist….for example, someone might be passing another vehicle uphill with a truck and trailer at GVWC, thus using the pedal to the metal and then if they have to abort the pass, thus letting of the pedal abruptly…if there was zero delay, the EB would immediately engage and likely float the exhaust valves…I am simply thinking/guessing that the smart engineers at Cummins (or maybe Chrysler, though I give the,m less credit…lol) programmed in the delay for it for engine safety reasons.

 

[jhenderson]

Now another question. Is everyone running the engine mounted pump? I was hot for the pump relocated to the inner fender but PacBrake says it's no longer available. Any other options? Thanks

 

[AEdelheit]

Both mine have the engine mounted pump, no issues with them. It makes the engine look a little cluttered and dipstick access is not as good but I cant hear or feel it and most compressors mounted elsewhere that Ive seen are fairly noisy and vibrate the whole truck unless they have really soft mounts but then they dont usually hold up as well.

 

[Tuesdak]

I would move the heavy metal and related items off the compressor outlet to "elsewhere" when engine mounting. (Pressure switch, 3 way connector, etc.) The weight of all the stuff with diesel vibration wears the compressor head threads out and causes leaks. It appears to be a frequent service item and only weak point I've seen on it.

Also order some of the special oil for it and lube the spool valve now and then.

 

[wcjp]

Very happy with the Pacbrake on my 2006. My engine mounted compressor died some time ago. Replaced it with an AirZenith which is overkill. Manual transmission. The Pacbrake is connected to the ECM. No lag for engagement. At 108k miles on the odometer I'm still on the factory brakes with at least half brake pad life.

 

[LWalsh]

I've had the engine mounted compressor work well for about 18 months, but has now insufficient pressure to actuate the brake. Checking with ThoroughBred Diesel about a replacement pump.

 

[Prairie Dog]

Very happy with the Pacbrake on my 2006. My engine mounted compressor died some time ago. Replaced it with an AirZenith which is overkill. Manual transmission. The Pacbrake is connected to the ECM. No lag for engagement. At 108k miles on the odometer I'm still on the factory brakes with at least half brake pad life.

So if you don't manually turn off the PB, it will engage between shifts?

Scott

 

[RBridenbaugh]

You have about 2 seconds between shifts before the exhaust brake kicks in on my 6 spd manual.

My first PacBrake pump lasted about four years. Excessive back flow through the pump. Newer pump has a check valve built in. No issues so far after four years.

Only had one issue with the on top of motor mounting location, that could have been prevented by just turning off the exhaust brake while climbing. Outside temperature in the 90's, climbed up a steep, very curvy 6 mi grade in the Sierra, with the 4,200 lb TC in the back. I had accidentally left the exhaust brake on. The constant cycling of the airbrake compressor (on the throttle exiting the curve, off the throttle entering the curve), high outside temperature and engine heat caused the air compressor to become heat soaked and the thermal cutoff switch to open. Took about 20-30 minutes for the thermal link to reconnect and the compressor to function again.

Once you get used to an exhaust brake, you will really miss it when going down a steep grade. The PacBrake is the best add-on for my truck with a load in the back.