Vehicle Diagnostic &
Engineering Guide Library
Internal engineering knowledge platform for Vincek d.o.o. — covering electrical systems, HVAC, pneumatic brakes, diesel powertrain, Cummins X11, and MAN D2676 diagnostics. All values in metric/SI standard.
Diagnostic Guide Collection
Comprehensive engineering guides covering electrical charging systems, HVAC refrigeration cycles, and pneumatic brake diagnostics for buses and trucks.
Alternator Charging Diagnostic Guide
Step-by-step voltage and circuit verification using a multimeter.
Bus HVAC System — R134a Refrigeration Cycle
Thermodynamic operation, component function, and flow analysis.
Air Brake System — Operation, Diagnostics & Repair
Pneumatic circuits, braking logic, and failure analysis.
Diesel Engine Diagnostics — Fuel, Turbo & Emissions
Common rail fuel injection, turbocharger, DPF, EGR, and SCR/AdBlue systems.
Cummins X11 CM2670 — Complete Training Suite
Dedicated teaching process and diagnostic guides for the Cummins X11 engine with CM2670 ECM. Covers engine architecture, XPI fuel system, VGT turbo, EGR, aftertreatment (DOC/DPF/SCR/ASC), UL2.2 DEF dosing, INSITE diagnostics, and overhead adjustment procedures.
Engine Overview
X11 architecture, XPI fuel, VGT turbo, EGR system, and specifications.
Aftertreatment System
DOC, DPF, SCR, ASC catalysts, UL2.2 DEF dosing, and regen control.
CM2670 Control System
ECM architecture, sensors, actuators, J1939 data links, and fault codes.
Key Skills & Procedures
Overhead adjustment, sensor testing, INSITE procedures, and maintenance.
MAN D2676 LOH Euro 6c — Complete Training Suite
Dedicated teaching process and diagnostic guides for the MAN D2676 LOH 12.4 L inline-6 engine. Covers engine architecture, Bosch CP 3.4+ fuel system, VGT turbo, AGR/EGR, aftertreatment (DOC/DPF/SCR), EDC17 control, valve adjustment, EVB exhaust brake, filling quantities, and A/C system data.
Engine Overview
D2676 architecture, CP 3.4+ fuel, VGT turbo, AGR/EGR, EDC17, and full specifications.
Repair Procedures
Valve adjustment, EDC17 removal, rail sensor replacement, AGR leak test, EVB setup.
Filling Quantities & A/C
Engine oil, gearbox, retarder, hydraulic, axle oil, R134a refrigerant, compressor oil.
Technical Values Reference Table
| System | Parameter | Value | Status |
|---|---|---|---|
| Alternator (24 V) | System voltage (engine OFF) | 24.8–25.4 V | Nominal |
| Alternator (24 V) | Charging voltage (engine idle) | 27.0–29.0 V | Nominal |
| Alternator (24 V) | Voltage drop B+ terminal | < 0.5 V | Nominal |
| Alternator (24 V) | Ground voltage drop | < 0.3 V | Nominal |
| Alternator (24 V) | AC ripple (diode test) | < 0.5 V AC | Nominal |
| R134a HVAC | Low-side pressure | 2–4 bar | Nominal |
| R134a HVAC | High-side pressure | 12–18 bar | Nominal |
| R134a HVAC | Compressor discharge temp. | 70–90 °C | Nominal |
| R134a HVAC | Cooling capacity (bus) | 20–40 kW | Nominal |
| Air Brake | System pressure | 8–12 bar | Nominal |
| Air Brake | Cut-out pressure | ~10–12 bar | Nominal |
| Air Brake | Acceptable leak rate | < 0.5 bar/min | Nominal |
| Air Brake | Brake chamber stroke | Per OEM spec | Check OEM |
| Diesel Engine | Common rail pressure (idle) | 300–400 bar | Nominal |
| Diesel Engine | Common rail pressure (rated) | 1800–2200 bar | Nominal |
| Diesel Engine | Injector leak-back (max) | < 80 mL/min | Nominal |
| Diesel Engine | Turbo boost pressure (max) | 1.8–2.2 bar | Nominal |
| Diesel Engine | DPF regen temperature | > 600 °C | Check OEM |
| Diesel Engine | AdBlue concentration | 32.5% urea | Nominal |
| Diesel Engine | DPF differential pressure (clean) | 2-5 kPa | Nominal |
| Cummins X11 | Rated power | 298 kW @ 2100 RPM | Nominal |
| Cummins X11 | Peak torque | 1966 Nm @ 1200 RPM | Nominal |
| Cummins X11 | XPI rail pressure (idle) | 400-600 bar | Nominal |
| Cummins X11 | XPI rail pressure (rated) | Up to 2400 bar | Nominal |
| Cummins X11 | VGT boost (rated) | ~2.0-2.5 bar | Nominal |
| Cummins X11 | EGR valve position | 0-100% PWM | Nominal |
| Cummins X11 | DPF regen outlet temp | 500-600 deg C | Check OEM |
| Cummins X11 | DEF dosing rate | ~2-5% of fuel | Nominal |
| Cummins X11 | SCR DeNOx efficiency | > 97% | Nominal |
| Cummins X11 | Overhead valve lash (intake) | 0.254 mm | Nominal |
| MAN D2676 | Rated power (LOH 37) | 368 kW (500 PS) @ 1800 RPM | Nominal |
| MAN D2676 | Peak torque | 2500 Nm @ 930-1350 RPM | Nominal |
| MAN D2676 | CP 3.4+ rail pressure (idle) | 350-400 bar | Nominal |
| MAN D2676 | CP 3.4+ rail pressure (rated) | 2000+ bar | Nominal |
| MAN D2676 | VGT boost (max) | 2.2 bar | Nominal |
| MAN D2676 | Valve clearance (inlet, cold) | 0.50 mm | Nominal |
| MAN D2676 | Valve clearance (exhaust, cold) | 0.80 mm | Nominal |
| MAN D2676 | EVB clearance (cold) | 0.60 mm | Nominal |
| MAN D2676 | Engine oil (with filter) | 42.0 L | Nominal |
| MAN D2676 | AGR leak test pressure | 3 bar / 30 min | Check OEM |
Diagnostic Decision Tree
Is system voltage below 24.0 V (engine OFF, 24 V system)?
Download Training Material
Alternator Diagnostic Checklist
R134a Bus HVAC Cycle Reference
Air Brake Leak Test Procedure
Workshop Safety Notes
Diesel Engine Diagnostic Checklist
Cummins X11 CM2670 Training Package
MAN D2676 LOH Euro 6c Training Package
Interactive Training Mode
Step-by-step guided diagnostics with interactive quizzes and knowledge checks.
FieldNotes — Real-World Diagnostic Tips
Lessons learned from the field — actual problems, root causes, and quick-fix solutions from Vincek d.o.o. fleet operations.