1985 Autocar — we work on any truck
If it runs diesel and needs help, we'll show up. Age is not a barrier — classic, vintage, or modern.
Mobile Chevy & GMC Truck Repair
Chevy & GMC Truck Repair in Charleston, SC — Duramax & Gas, We Come to You.
On-site repair and diagnostics for Chevy and GMC work trucks — 6.6L Duramax diesel and 5.3/6.0/6.2L Vortec gas, with a focus on Silverado and Sierra 2500 and 3500 and up. We come to your yard, jobsite, terminal, or roadside location, test the actual cause, and give you a clear repair direction before parts get thrown at the problem.
- Duramax LB7–L5P: CP4, injectors, DPF/DEF/EGR derate, turbo, Allison
- Vortec 5.3/6.0/6.2 gas: AFM/DFM lifters, misfires, oil consumption
- Silverado & Sierra 2500/3500 and up — work trucks and fleets
6.6L Duramax — Diesel (LB7 through L5P)
Known Duramax problems we diagnose on-site
CP4 & injectors
CP4.2 pump failure and metal contamination, injector balance rates, hard start, misfire, white smoke, and fuel-in-oil dilution traced before we tear anything down.
Glow plugs & hard start
No-start and long crank in the cold, failed glow plugs and controller, low rail pressure, and air-in-fuel confirmed with live data instead of guessing.
DPF / DEF / EGR & derate
Failed regens, plugged DPF, DEF quality and dosing faults, EGR and NOx sensor codes, and speed derate countdowns diagnosed to keep the truck moving.
Turbo & Allison trans
Variable-vane turbo sticking and overboost/underboost, plus Allison 1000 harsh shifts, slipping, and limp mode checked at the truck.
5.3 / 6.0 / 6.2L Vortec — Gas (AFM/DFM)
Known Vortec gas problems we diagnose on-site
Collapsed AFM/DFM lifters
The classic GM lifter tick, misfire, and dead cylinder from Active Fuel Management and Dynamic Fuel Management. We confirm the exact cylinder and lifter before any teardown.
Misfires & ignition
Rough idle, stumble, and P0300-series misfire codes traced to coils, plugs, injectors, or a mechanical cylinder problem with live data and testing.
High oil consumption
AFM-related oil burning, fouled plugs, and low-oil warnings on 5.3 and 6.2 engines evaluated so you know whether it is rings, the AFM system, or a leak.
General driveability
Stalling, hesitation, reduced-power messages, and check-engine lights on Vortec gas trucks diagnosed to the real cause before parts.
Service & Repair Menu
General work on 2500/3500 Chevy & GMC and up
Diagnostics & scan
Full code scan, live data, and targeted testing across engine, trans, chassis, and body modules on Duramax and Vortec trucks.
Ball joints & front end
GM independent front suspension wears these out — ball joints, control-arm bushings, and front-end play checked and replaced on-site.
CV axles & steering
Front CV/half-shaft boots and joints, tie rods, pitman and idler arms, and steering slop on the IFS front end.
Wheel bearings & hubs
Noisy or failing front hub bearing assemblies and ABS/wheel-speed faults tested and replaced where the truck sits.
Brakes
Pads, rotors, calipers, and brake hydraulics on 2500/3500 work trucks, plus service on larger units.
Oil changes & scheduled PM
Duramax and Vortec oil and filter service, DEF top-off, and full scheduled PM — including recurring fleet PM.
Suspension
Shocks, leaf springs, U-bolts, and worn steering/suspension components on loaded work trucks.
Electrical & charging
Batteries, alternators, starters, grounds, wiring, and parasitic-draw and no-start diagnostics.
A/C, heat & cooling
A/C and heat performance, plus cooling-system leaks, thermostats, water pumps, and overheating diagnosed on location.
Why Call a Mobile Mechanic
Skip the tow and the dealer wait
Getting a Silverado or Sierra work truck to a dealer or shop means a tow, a bay in someone's queue, and days of downtime before anyone has even looked at it. A lot of that is avoidable. Many Duramax and Vortec faults can be diagnosed — and often repaired — right where the truck is parked.
Lowcountry Diagnostics brings the diagnostic equipment to the truck and works through the fault systematically. Whether it is a CP4 concern, a DPF derate, a collapsed AFM lifter, or worn front-end parts, the goal is a clear answer: what failed, what was tested, what needs to happen next, and whether it can be handled on-site.
Why fleets & owners call us
- Duramax diesel and Vortec gas expertise in one call
- Testing before parts replacement — no guessing
- Mobile service where the truck is sitting
- Clear written findings and next steps
- 24/7 Charleston-area availability
Need a Chevy or GMC truck mechanic in the Charleston area?
Call or text Lowcountry Diagnostics and we will come to the truck — Duramax or gas.
Common Chevy, GMC & Duramax questions
Do you work on both Duramax diesel and Vortec gas Chevy and GMC trucks?
Yes. We handle the 6.6L Duramax diesel from LB7 through L5P and the 5.3L, 6.0L, and 6.2L Vortec gas engines. Most of our Chevy and GMC work is on Silverado and Sierra 2500 and 3500 work trucks and up, plus larger commercial and fleet units.
Can you diagnose a Duramax DPF, DEF, or derate problem on-site?
Usually. We read the codes and live data, check regen status, DEF quality, EGR and NOx sensors, and figure out why the truck went into a speed derate — where the truck sits, so you avoid an unnecessary tow or the wrong parts.
My 5.3 or 6.2 has a lifter tick or misfire — is that the AFM/DFM problem?
Often. The Active Fuel Management and Dynamic Fuel Management lifters on GM Vortec engines are known to collapse and cause ticking, misfires, and rough running. We confirm which cylinder and lifter before any teardown so you are not paying to guess.
Do you come to my yard or jobsite for Chevy and GMC trucks?
Yes. We are mobile and come to your yard, jobsite, terminal, shop, or roadside location throughout the Charleston area. Running a mixed fleet with smaller vehicles too? Ask us. Call or text (843) 310-0995.
Request Chevy & GMC Truck Service
Tell us where the truck is and what it is doing. For urgent truck-down calls, calling or texting is fastest.
Urgent breakdown? Call or text (843) 310-0995 now.
Recent Repair Photos
A look at the repairs we make
Real field photos from Lowcountry Diagnostics — from engine diagnostics and electrical to hydraulic, HVAC, and heavy-duty truck service, handled on-site across the Charleston area.
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