01
Capture
Verify the complaint. Save codes, freeze-frame and a cold-start data log before clearing anything.
915 Industries Technical Library
Diagnose the fault.
Not your wallet.
Real diesel troubleshooting organized by engine, symptom and system. Start with data, prove the failure, and stop firing expensive parts at a problem you haven't measured.
Educational starting points—not a replacement for year-specific service information. Common-rail fuel can cause fatal injection injuries. Never loosen a high-pressure line on a running or cranking engine.
Start with the complaint
What is the truck doing?
The same trouble code can have five causes. The symptom, operating condition and live data decide which road to take.
Cranks / No Start
Separate electrical, synchronization, low-side fuel, injection-pressure, air and mechanical failures in the right order.
Open diagnostic pathRough / Smoke / Miss
Use contribution data, fuel quality, sensor plausibility and mechanical checks before calling an injector.
Open diagnostic pathLow Power / No Boost
Prove the intake, charge-air, exhaust, turbo-control and fuel-delivery sides under the load that causes the complaint.
Open diagnostic pathElectrical / No Comms
Find voltage loss, bad grounds, network faults and weak series/parallel battery banks with measurements—not guesses.
Open diagnostic pathEngine-specific diagnostics
Choose your platform
Every card opens a dedicated guide with platform-specific no-start, rough-running and scan-data checks.
Cummins · Power Stroke · Duramax
Pickup and commercial diesel systems
Pickup and commercial diesel systems
1989–2007
Cummins 5.9
VE, P7100, VP44 and common rail—four systems, four correct diagnostic paths.
Open guide
2007.5–current
Cummins 6.7
Rail pressure, airflow and aftertreatment must tell the same story.
Open guide
2003–2007
Ford 6.0 Power Stroke
Base oil, high-pressure oil, FICM power and synchronization before injectors.
Open guide2011–current
Ford 6.7 Power Stroke
Clean fuel, strong cranking, verified supply and rail-pressure tracking.
Open guide
2001–current
Duramax 6.6
Choose the RPO first: LB7 through L5P do not share one test sheet.
Open guideSan Antonio diesel diagnostics
Need hands-on testing?
Bring us the symptoms, codes and what has already been replaced. We'll start with the truck—not the story the parts cannon told.
Book diagnosticsA repeatable method
Four moves before one part
Good diagnostics is controlled elimination. Each test should tell you where to go next.
02
Compare
Compare commanded versus actual values, and compare sensors that should agree before the engine starts.
03
Load test
Test power, grounds, fuel delivery and air-path control while the failure is happening.
04
Isolate
Divide the system into sections, prove the failed section, then test the component before replacement.
Fundamentals
Diesel theory & operation
Compression ignition, common rail, HEUI, fuel control, turbocharging, smoke clues and why commanded-versus-actual data matters.
Learn the systemsElectrical fundamentals
12V & 24V diagnosis
Series and parallel batteries, voltage-drop testing, starting and charging systems, grounds, relays and CAN-network basics.
Open electrical guideStill chasing the fault?
Call 915 Industries at (915) 247-2782. We handle diesel diagnostics, electrical faults, fuel systems, fabrication and calibration work in San Antonio.