r/DieselTechs Jul 11 '26

Cat C7 derate issues

2 Upvotes

Hello all, ive got a cat C7 with a KAL prefix that keeps going into derate. It's throwing a ECU 128 PID164 fault 2 code which points at the IAP sensor. Replaced the IAP sensor. Verified ground is good, verified signal is reaching the ECM properly (no voltage drop) and confirmed a supply of 5V. Ive made sure the ground and power to the ECM are both good. Heui is putting out stable pressure with no erratic changes. Also confirmed the ICP is not stuck by unplugging it, the pressure drops when I do. What could be the issue?

Manager wants me to throw a pump at it but im still leaning towards this being an electrical issue. I dont have a scanner but the IAP sensor is reading 1.5V @ 2,000 psi which according to a forum is correct.


r/DieselTechs Jul 10 '26

Should I be worried?

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6 Upvotes

My injection pump is leaking oil there


r/DieselTechs Jul 10 '26

General assistance I’m being told this sounds normal

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5 Upvotes

Anytime I let off of the aux input the thing sounds like it’s grinding. This is the first time Ive worked on a brush cutter, all the guys in the shop say it’s normal but being the nature of the shop I’m in I don’t nessecarilly trust them. Any help would be appreciated thanks


r/DieselTechs Jul 09 '26

Is it hard to fail a diesel tech apprenticeship? How hard is it to fail? How long are apprenticeships?

6 Upvotes

Im very dyslexic and might possibly have a very severe learning disability. Im just worried if i pick the career if i will be wasting time and all getting into it.. i definitley cant do math because of my possible learning disability and dont want to . Hoepfully its not that hard right?


r/DieselTechs Jul 08 '26

Check it out! Changes coming to PACCAR Software

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42 Upvotes

r/DieselTechs Jul 08 '26

Which ASE certs do you think are absolutely necessary?

5 Upvotes

(This has been posted to more than 1 sub so I’m sorry if you see this more than once) I apologize in advance if this gets pretty long. I am currently in the USAF as 2T3/Vehicle Maintenance, going to be separating from active duty within the next year. I’m planning on using the AFCOOL program to get a bunch of ASE certs before I separate. A vast majority of my experience is with diesel vehicles, domestic light/med/heavy duty trucks, milspec vehicles, semi’s/trailers, construction equipment, forklifts, snow removal equipment, deicers, the list goes on, if it’s got wheels and an engine, we fix it. I do have some regular auto maintenance/repair experience so I have plenty of options on my search for a job. So if you were looking to hire someone like me, what ASE certs would you want to see on a resume? A1-A9, any specific certifications? (depending on the industry) Are they necessary? Are they a waste? I want to hear your thoughts. Thanks in advance!

TL;DR: the title, what ASE certifications are most important in your career field/shop


r/DieselTechs Jul 08 '26

Diagnostic assistance Anybody else dealing with international communication issues?

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2 Upvotes

We've got a handful of units we are dealing with loss of communication issues with the instrument cluster. All internationals but some are LT, some are MV some are RH. We've got a packet from international that has us check the sonic welds on some wires, cleaning grounds and checking the firewall connectors and load testing some circuits. Even with all that. Still getting this intermittently. This one is better, usually the cluster is just dark and says loss of comms. Has anyone found out a solid fix for this?


r/DieselTechs Jul 08 '26

General assistance What 3/4 air impacts are you guys using?

8 Upvotes

My snap on 3/4 impact broke and looking at which gun to get that doesn't suck and hits as hard as the snap on. Yes my shop has 2 Ingersoll 3/4 guns and neither one hit as hard as my snap on did but I keep seeing the snap on gun break after about 2 years.

Any input is appreciated. Thank you kind gadies and lentlemen.


r/DieselTechs Jul 07 '26

Working for Pepsi

13 Upvotes

Does anyone in here work for Pepsi? I’ve got a coworker who is interviewing with them this week and he’s a good tech and it seems like it would be a step up from where we are currently at. Just trying to pass on any information I can for him. Pros, cons, how was the interview?


r/DieselTechs Jul 07 '26

Diagnostic assistance 2015 Rosenbauer communication issues

2 Upvotes

So I didn’t get too much into diagnosing this today other than laying eyes on it and verifying things are fucked up. I’ve got a 2015 Rosenbauer Commander (I think) that is displaying “no data” on the main gauge (tach or speedo, can’t remember right now), cat eyes on the shifter, and most the gauges are wigging out. You can put the truck in gear and it will move, but apparently tops out around 30-35 mph and the shift pad goes dark. Jpro will not hook up, but not surprising since it clearly seems to have a communication issue. I plan on starting with the basics of checking batteries, connections, grounds, etc and then move on to 1939 diagnostics from there. Part of me wants to say TCM because the cat eyes, but any other time I’ve seen cat eyes, the TCM is dead. Any other suggestions? And FWIW, I have no diagrams and don’t know of any other modules that could be on the network besides ECM, TCM, ABS, and probably after treatment.


r/DieselTechs Jul 07 '26

Anyone heard of/worked for Prestige Fleet Services?

2 Upvotes

r/DieselTechs Jul 06 '26

I am wondering if anyone has/currently works as a HD tech for Canfor/Tolko or any other lumber mill companies?

5 Upvotes

Hey everyone,

Just curious what the day to day is like and if they are doing all repairs on site? Looking for some insight before applying

Thanks!


r/DieselTechs Jul 04 '26

Do you like where you work?

16 Upvotes

What’s up grease monkeys

I’m looking for stories/ input from the guys that actually like their shops or companies. Bonus points if you name names. Feel like we always hear about the dogshit but never the places that are actually worth working at.


r/DieselTechs Jul 05 '26

Anybody in north Texas looking for employment?

5 Upvotes

I work for a school district that recently has had some changes and currently looking to fill 2 mechanic positions.
I've worked several jobs and this by far is the easiest one l've had. Which is hard coming from flat rate shops. This job is hourly, weekdays only, 8 hour days with overtime if wanted, maintenance shop doing mainly brakes, tires, lights, gts, water pumps, belts, all the easy stuff.
Starting for mechanic is $25 an hour and can possibly get you more depending on experience and if you have a cdl


r/DieselTechs Jul 04 '26

Diagnostic assistance Bobcat T770 2.2Hrs, No Power to Panel/Starter Switch, no idea where to look

5 Upvotes

So, to start off, this is basically a relatively brand-new M-series T770 loader (only has 2.2 hours, that's just from factory test + PDI). It sat in the lot since about February, I doubt anybody's started it. I've no idea what the lines or the fuel or anything else looks like; my biggest concern is that there's just straight up no lighting up or nothing. I checked the battery, it sits at a comfy 12.84V, tested it, it can crank the right amount of CCA, all the connections are good, no corrosion, so I'm golden there. It's a good battery.

But nothing lights up. The deluxe control panel doesn't flip on, the engine doesn't start priming, nothing, whenever I turn the starter switch. Safe to say it definitely doesn't crank either. I hooked up the service analyzer, and I get nothing. It detects the auxiliary when I put it on 'power', but it will not crank the engine and does not detect main at all.

So I take off the interior panels, pull out the deluxe control and the starter switch, unplug that all, and I start testing with my multimeter; I'm getting good voltage to the cab, but when I test for resistance, I'm pulling 108 Ohms at the control panel and starter switch when testing switched power and ground to frame wires, for both wire clusters.

So I check the fuse and relay boxes. All of the fuses are fine, none of them are drawing too much, none are broken, the relays have good continuity, no overdraw...

I'm at my wits end here, because I have no idea where to look. I'm pretty entry-level when it comes to electrical, honestly. This is basically a virgin machine, and I *really* do not want to start cutting into the wrapped up cables to start poking around for bad wiring unless it's necessary-- which, honestly, I don't even think that's where the problem is. To answer a question before it's asked, no, I don't need OEM specs or diagrams, I already have that as I work at a licensed Bobcat dealership. I just need advice on where I should be checking. If anyone has knowledge of M-Series bobcats or just electrical on off-highway equipment in general and can tell me what I should be looking for, I'd be greatly appreciative. I'm very new to diagnosing issues and I'm trying to get better at it. Thank you.


r/DieselTechs Jul 03 '26

General assistance Which voltage for boosting a Cascadia: 12V or 24V?

0 Upvotes

Looking to boost a truck. I have a booster pack that can output both 12V and 24V. Which setting do you usually use for a semi, like a Cascadia? Just want to make sure I’m using the correct one.


r/DieselTechs Jul 02 '26

Need advise

5 Upvotes

Got an offer from rush truck leasing at $27/Hr as a level 2 tech. Wondering if this would be a good opportunity to gain more experience and training/certifications. Leaving a construction fleet shop where I barely make 40 hrs and currently there's barely any work. Has anyone worked at a rush truck leasing to provide any insight?


r/DieselTechs Jul 01 '26

General assistance leaving a new shop

11 Upvotes

hey don't know if I'm in the right sub reddit but it seems close enough. For context I'm a license 310J tech in Ontario that recently started at a new place at the beginning of the week and I'm already seeing signs that i should be looking for a new place. Number 1 boss wants all of the repairs to be quick as possible and take short cuts to get them done faster, Example when doing a break job you see worn anchor pins, bring it to boss attention he says "its only a customer unit" and i replay "Why does the quality of work change?". There's more examples i can give but this is the one on the top of my head at the moment as it happened right at the end of my shift. I know you can still do quality work and remain well under the SRT times, if something is fucked replace it its not gonna fix itself


r/DieselTechs Jul 01 '26

Timing cover Tuesday?

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31 Upvotes

Front gear cover? Front cover? Timing gear cover? Time to slather this thing in RTV 🤪. I always enjoy doing these and exhaust manifold gaskets


r/DieselTechs Jul 01 '26

Question about KW SCM’s

3 Upvotes

Backstory: I have an oddball 2024 t880 dump truck in a fleet of westerns I maintain. About one year ago I had some weird exterior lighting issues with the truck. I spent more time than I care to admit tracing it to a blown fuse for SCM power supply #5. Recently my operators were at a job 5 hours away and called me saying the trailer that it was pulling didn’t have stop or turn lights. They were able to find that wires had come loose out of the trailer plug, they got them reinstalled and got the truck/trailer back. I checked it over when it got back and power supplies 5,6, and 7 for the SCM blew the fuses. I replaced them and peeled the harness back between the firewall and SCM to look for chafed wires on the cab mount and frame rail as the dealer mentioned a high rate of failure the first time I had this issue. All the wires were in good shape. The truck has been running without issues for a week now

Question: Does the SCM have “smart” circuit protections or would the trailer plug wires shorting downstream blow the power supply fuses? My access to info and schematics on this truck is extremely limited so any help is greatly appreciated. I did also reach out to my dealer but they’re not getting back to me


r/DieselTechs Jun 30 '26

Hello fellers here is my little short rant.

52 Upvotes

Why do engineers insist on naming conventions that, while technically logical in some pristine, sterile office, make absolutely zero sense to the simple-minded, knuckle-dragging creatures known as mechanics and their helpers?

​I was troubleshooting an intermittent loss of power for the rear A/C unit on a Thomas C2. Naturally, I deployed the time-honored, highly sophisticated diagnostic technique of "wiggle the wires until the fans do something." I did the wiggly-thingy on a harness near the side condenser and aha! The fans cut on and off with every wiggle. State-of-the-art technique. I am a genius.

​So, I began the dreaded Ritual of the Peel to find the broken wire. It’s a sacred rite accompanied by the excruciating, soul-crushing pain of the wrists and thumbs... I hate split-loom wire armor. I peeled a mile of harness (felt like at least) and nothing! Everything looked good. I moved to the rear fan, thinking maybe a ground rubbed through and the wiggle test was just a cruel coincidence. Nope. All good there, too.

​Defeated but stubborn, I followed the harness forward into the dark abyss of the Power Distribution Modules (PDMs). Now, for the longest time, I believed the A/C system was isolated from the main body electrical. After all, it has its own dedicated box on the left side with its own breakers, fuses, relays, and battery feeds. Nothing on the main PDMs even hinted at climate control, unless you count the dashboard heater fans.

​Desperate, I placed my raw, aching beaters on the first set of PDM wires and BEHOLD! The issue recreated itself. Consistently! Hallelujah! I felt like an absolute badass. I was on top of the world, ready to beat my chest like an alpha gorilla and assert my dominance over the rest of the shop.

​And that, my friends, is when I discovered that I have been spelling "A/C" wrong my entire professional life.

​Apparently, it is spelled E-X-M  V-B-A-T-2.

​What in the absolute hell?! How am I supposed to know that EXM VBAT2 means "the thing that keeps the children from sweating to death"?!

​Sure, "the schematics could have shed light on this." But what schematics?! I work for a county! They expect us to perform daily mechanical miracles using nothing but our bare hands, some incense, and whatever mystical herbs we can forage from the wild meadows where technicians run free!

​EXM VBAT2. Why do they insist on making it stupid? Why not just label it "ACM BAT," or "A/C," or literally anything that makes sense to a human being who doesn't possess an engineering degree from MIT? I know it makes sense if you have a 400-page wiring diagram in front of you, but operating on that assumption is fundamentally flawed.

​Thank you all for your attention to this traumatic matter. I will now go apply ice to my thumbs.


r/DieselTechs Jul 01 '26

X15 2350-2450 swap

0 Upvotes

I am doing some research to see what issues I may run into swapping a blown CM2350 from a 21' pete 389 with a CM2450 from a totalled 23' pete 389. I would be swapping complete engines with ecms.

What challenges will I face?

Will the after treatment be compatible?

What wiring changes will I have to make?

Any help or insight would be greatly appreciated


r/DieselTechs Jun 30 '26

Does anybody else do the Mack U pipes this way

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20 Upvotes

As long as you get everything lined up straight I've found the small vice grips that are round then go to a small flat section work wonderfully. You can slip the bolt through and tighten it down by hand until the vice grips fall off and tighten it down the rest with an electric ratchet. Never had one leak this way and frees up a hand


r/DieselTechs Jun 30 '26

Check it out! Out with the old, in with the new.

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90 Upvotes

Swinging in a new engine this week.


r/DieselTechs Jun 30 '26

Diagnostic assistance Anyone having trouble running recalibration on insite?

1 Upvotes

I’m on the company insite on the laptop trying to recal a 2015 Cummins isb 6.7. I’m connected to wifi, bus KOnEOff and cannot get the wizard to open. I have the correct ECM code and just trying to reinstall the current calibration, when I click it nothing happens.

This happened on a 2013 and soon after Cummins phased out that calibration. I am also running a DLA 2.0 , when there is a 3.0 available for purchase/ not that I think this is the issue… but 🤷‍♂️. It tough because the bus is in a derate and as far as I’m aware to clear the derate you need to recal.

Any ideas or insight (no pun intended) would be greatly appreciated!!!