Working on a 1996 379 Peterbilt with the Cummins N14 with Celect ECM. Engine brake is inop. I'm looking for wiring schematic to figure out location of the OEM engine brake relay. I have access to cummins QuickServe Online, so I got the engine side covered. Hoping someone has a Peterbilt schematic that will help me out. Truck is beat, relay box in cab has no cover and nothing's labeled. Thanks
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1996 Pete 379 N14 Engine Brake
- Thread starter WCR73
- Start date
Truck Shop
Senior Member
Probably have to go to Pete and have them run off a copy of schematic. IIRC there also is a breaker panel left of the clutch pedal, if you haven't found that already.
Member-Junkyard might know where it's located.
Truck Shop
Member-Junkyard might know where it's located.
Truck Shop
Junkyard
Senior Member
I don't recall off the top of my head which relay under the dash is engine brake. Somewhere in the shop I think I have a 379 factory manual. I'll see if I can scrounge it up. A few continuity checks might help you find the relay or the spot it's supposed to be.
Have you popped and valve cover and pushed on an actuator to see if they're even adjusted tight enough to work? Clutch switch functioning? No parameters set to keep them from working?
I did a quick google search and found quite a few different fuse panel diagrams and didn't see a separate fuse or relay for the engine brake by itself. Tried to look at a few schematics but couldn't blow them up enough to read what went where. Does 96 have a panel or anything under the hood on driver's side where harness goes into cab?
Might be one of those deals where you end up chasing wires to find the culprit....not much fun.
Have you popped and valve cover and pushed on an actuator to see if they're even adjusted tight enough to work? Clutch switch functioning? No parameters set to keep them from working?
I did a quick google search and found quite a few different fuse panel diagrams and didn't see a separate fuse or relay for the engine brake by itself. Tried to look at a few schematics but couldn't blow them up enough to read what went where. Does 96 have a panel or anything under the hood on driver's side where harness goes into cab?
Might be one of those deals where you end up chasing wires to find the culprit....not much fun.
92U 3406
Senior Member
My first go to would be to test the clutch switch. Especially if both cruise and jake aren't working.
pushbroom
Well-Known Member
Whats the last six of your s/n
Last 6 of VIN are 397343... I had Insite hooked up to it while I was troubleshooting a faulty intake air pressure sensor, and looked at the few parameters that are visible with J1708 and it's recognizing engine brake switch functioning on and off in the cab, idle validation ok. It's sidework so I like to have as much info before I go take the time to fix ****.
I have access to Peterbilt ECAT at work, but I guess our subscription only lets us look up the trucks in our fleet. I've tried in the past to search for VIN's outside of our fleet and it says NOPE!
Thanks for the responses fellas.
I have access to Peterbilt ECAT at work, but I guess our subscription only lets us look up the trucks in our fleet. I've tried in the past to search for VIN's outside of our fleet and it says NOPE!
Thanks for the responses fellas.
pushbroom
Well-Known Member
Truck came with a series 60 from factory. Someone has swapped out engines since then, unless the s/n is wrong. Truck does show as a 96 379. The diagrams are all for a series 60, so I attached 2 generic schematics for 379s.
yup, sure as s***.... gave you the wrong VIN. 397434 is correct last 6.... apologize about that. Guess the new year gave me dyslexia.
This guy is anxious to get his eng brake working. He has this rig, a 96 Pete with reliance transfer setup... and he also has a 70's Kenworth with the same setup. We had the terrible October wildfires come through Santa Rosa, ca and wipe out 5,100 homes, 8000 total in the greater area. They are paying end dumps and transfers $140 an hour to haul the debris away for the widespread cleanup... pretty wild. Clean up is going to last for months
This guy is anxious to get his eng brake working. He has this rig, a 96 Pete with reliance transfer setup... and he also has a 70's Kenworth with the same setup. We had the terrible October wildfires come through Santa Rosa, ca and wipe out 5,100 homes, 8000 total in the greater area. They are paying end dumps and transfers $140 an hour to haul the debris away for the widespread cleanup... pretty wild. Clean up is going to last for months
pushbroom
Well-Known Member
Haha. Wondered that. Truck shows a 96 379 with a N14 now. You will still have to use the above diagrams but i did find some more specific ones for you.
Also like 92U said above, start at the clutch switch.
Also like 92U said above, start at the clutch switch.
DMiller
Senior Member
Clutch switch, trailer brake pressure switch, foot brake pressure switch, throttle switch, power from the dash control into the stagger (123)switch, the stagger control, then off to the rest of the system.
What is the purpose of brake pressure switches as far as effecting the engine brake?
Truck Shop
Senior Member
Cruise
Truck Shop
Truck Shop
Thanks truck shop, I wish all my questions could be answered with one word....
ok so in case anyone gives a s*** or not, here's what happened with the inop engine brake. Before I started troubleshooting this thing, the owner went down to the local Peterbilt dealership parts department for a new engine brake on/off dash switch just to throw an easy part at it and see if it cured the problem. He brought the old 4 blade switch with him along with the VIN. Parts guy brings out a 2 blade switch. Owner questions young guy behind counter, parts guy had 2 others behind the counter reassure him that the 2 blade would work in place of a 4 blade. He took their word, swapped switches out. Still inop...
I had Insite linked up a while back, all visible PIDs were functioning OK. Even engine brake on/off. That's all I had time for
Fast forward to today. I finally got back on the truck. Started locating all the things that make the jake's work. All was checking out ok. Finally found where all the cummins celect stuff is in the cab, (just to the right of steering column a fuse block and a relay block) found engine brake relay. I had no trigger power at pin 85 of relay.
Ended up getting back to brake on/off switch. At this point I didn't know the owner had swapped switches... Remember that 2-pin/4-pin thing? One pair of pins is 5v from the ecm, 5v gets sent to ecm when switch is on. Other pair is the 12v trigger side of the engine brake relay. This is the pair of pins that was missing from switch. I was getting the signal to ecm but no power to relay. That's why Insite would show the engine brake functioning on/off. Easy fix at that point. Got a 4 pin 2-pole switch, engine brake working fine.
My point here isn't about the troubleshooting. This was probably elementary for most of you veterans. My point is the guys that promised the owner "this is the right switch". when a guy lays a 4 pin switch on the counter, they hand him a 2 pin and say you don't need the 4-pin.... see this kind of stuff all the time. Owner said they were a bunch of young guys with attitudes, could tell they could care less of the switch was right or not.
What's it take for a place to get a good parts guy??? Or one that gives a s***. No one cares anymore. Do these parts houses not think that a good parts guy is key to a successful business??
There's a NAPA in town, had THE best all around truck/equipment parts guy i have ever met. Used him heavily in October/November after the fires when our equipment was running 24/7 at work. 2 months later I found out that he got a sweetheart offer to go run the parts department for the biggest construction company around. NAPA probably had no clue what they were loosing. Being that parts are Their money maker, I would have doubled his salary. Especially due to the fact that anyone else working there will ask if my truck is auto or manual and 4x4 or 4x2 when buying wiper blades.
Someone rant with me
ok so in case anyone gives a s*** or not, here's what happened with the inop engine brake. Before I started troubleshooting this thing, the owner went down to the local Peterbilt dealership parts department for a new engine brake on/off dash switch just to throw an easy part at it and see if it cured the problem. He brought the old 4 blade switch with him along with the VIN. Parts guy brings out a 2 blade switch. Owner questions young guy behind counter, parts guy had 2 others behind the counter reassure him that the 2 blade would work in place of a 4 blade. He took their word, swapped switches out. Still inop...
I had Insite linked up a while back, all visible PIDs were functioning OK. Even engine brake on/off. That's all I had time for
Fast forward to today. I finally got back on the truck. Started locating all the things that make the jake's work. All was checking out ok. Finally found where all the cummins celect stuff is in the cab, (just to the right of steering column a fuse block and a relay block) found engine brake relay. I had no trigger power at pin 85 of relay.
Ended up getting back to brake on/off switch. At this point I didn't know the owner had swapped switches... Remember that 2-pin/4-pin thing? One pair of pins is 5v from the ecm, 5v gets sent to ecm when switch is on. Other pair is the 12v trigger side of the engine brake relay. This is the pair of pins that was missing from switch. I was getting the signal to ecm but no power to relay. That's why Insite would show the engine brake functioning on/off. Easy fix at that point. Got a 4 pin 2-pole switch, engine brake working fine.
My point here isn't about the troubleshooting. This was probably elementary for most of you veterans. My point is the guys that promised the owner "this is the right switch". when a guy lays a 4 pin switch on the counter, they hand him a 2 pin and say you don't need the 4-pin.... see this kind of stuff all the time. Owner said they were a bunch of young guys with attitudes, could tell they could care less of the switch was right or not.
What's it take for a place to get a good parts guy??? Or one that gives a s***. No one cares anymore. Do these parts houses not think that a good parts guy is key to a successful business??
There's a NAPA in town, had THE best all around truck/equipment parts guy i have ever met. Used him heavily in October/November after the fires when our equipment was running 24/7 at work. 2 months later I found out that he got a sweetheart offer to go run the parts department for the biggest construction company around. NAPA probably had no clue what they were loosing. Being that parts are Their money maker, I would have doubled his salary. Especially due to the fact that anyone else working there will ask if my truck is auto or manual and 4x4 or 4x2 when buying wiper blades.
Someone rant with me
RZucker
Senior Member
I'm not really sure if you want me to join your rant. We could go on for pages...
DMiller
Senior Member
Same here, when I have to go behind the counter to tell the guy with the computer he's on the WRONG page I figure I may as well ask someone else or go somewhere else. Nobody worth their salt it seems is getting hired or if are they don't give a ****.
John C.
Senior Member
Hey, what does a parts guy have to know! They get paid to sit in a chair in front of a screen and sell parts that the store owner's believe a person has no other choice but to buy from them. Why would they pay that parts guy any money to stay and they usually hassle them to make phone sales calls out or stock shelves or sweep the floors when not taking care of a incoming calls. The owners think they can't afford to do any training. Now throw all the politics on top of that and getting out of the parts business becomes a priority for an older person.
not to mention you will never get a dollar back of lost time for the wrong parts. i hate napa anymore corporate took all the stores over around me i cant even get waited on at the counter without them trying to take a phone call the poor guys cant even get me the right grease with the napa number. was down at the kenworth dealer getting some parts and also need a gear shift boot and the guy pulled up the price and he said oh wow thats cheap let me check on that comes back well its right that will be 35 bucks i said no thanks went down the road to fleet pride got it for 15 its ridiculous. i find no one cares because they dont know they need to or there not held accountable for there mistakes that cost us time and money i will stop here
Truck Shop
Senior Member
When I call to order parts I have the part numbers and quantity ready. I don't have time to wait or set on hold while someone looks up each part number taking forever
then saying the computer is slow or blaming it on a new program. I have most of the common part numbers in my head and the last six serial numbers for five different
series of trucks the company owns. A simple order from me is usually $1,500 to $4,000. I have three outside parts salesman calling on the shop every week so if there
is a problem there going to hear about it. When I call for parts I ask for certain counter people. In my situation our accounts with these outfits are so big they can't
afford to p!$$ me off. But I hear what everyone is saying, when you call or walk up to a parts counter you have entered the DEAD ZONE.
Truck Shop
then saying the computer is slow or blaming it on a new program. I have most of the common part numbers in my head and the last six serial numbers for five different
series of trucks the company owns. A simple order from me is usually $1,500 to $4,000. I have three outside parts salesman calling on the shop every week so if there
is a problem there going to hear about it. When I call for parts I ask for certain counter people. In my situation our accounts with these outfits are so big they can't
afford to p!$$ me off. But I hear what everyone is saying, when you call or walk up to a parts counter you have entered the DEAD ZONE.
Truck Shop
I thought it was just me. My local NAPA I've had an account with for something like 30 years & the FleetPride across the bridge are frickin' worthless since the "old hand" counter guys left. I did have a good experience a while back at the NAPA in Missoula MT when I had fuel filter problems on the road and no spares onboard- those guys were great. I walked through the rail yard to their place from where I parked the night before, they knew right off what all I needed & they wouldn't take a no to giving me a ride back to the rig.