Navistar International® LT RH and LoneStar Series Schematics Manual 0000018825 – PDF DOWNLOAD

The Body Control Module is the central nervous system of these trucks. This section provides complete BCM designs for both X15 and A26 applications, including all major communication networks that keep the truck talking to itself and to external systems.

You will find detailed schematics for:

• ABS Private network
• Cab J1939 (250 Kbps)
• Engine Private J1939 for both A26 and X15
• Fusion Private J1939
• Low Speed J1939 (125 Kbps)
• Telematics J1708
• Body J1939 splice packs (1024, 1025, 1029) and multi-splice configurations
• Powertrain J1939 (500 Kbps) for Allison 3K, Eaton UltraShift+, Endurant, Manual, and TC10 transmissions — separate designs for A26 and X15

These diagrams show exact pinouts, termination points, and how the different networks interact. When you have a communication fault code or a module that will not respond, this is the section that tells you where the wires actually go and how the splice packs are laid out.

Engine and transmission integration is critical on these platforms. The manual separates A26 and X15 ECM designs and provides dedicated powertrain network diagrams for every major transmission option.

Coverage includes ECM pinouts and supporting circuits for both engines, plus transmission-specific J1939 and hard-wired interfaces for Allison, Eaton UltraShift+, Endurant, manual transmissions, and TC10. You also get body-builder powertrain interfaces, PTO circuits (single and dual, with and without clutch interlock), and auto-neutral logic for certain automatic transmissions.

Technicians working on performance complaints, transmission range issues, or PTO operation will find the exact circuits needed to verify inputs and outputs without guessing.

Lighting is one of the most frequently serviced areas on Class 8 trucks, and this manual covers it exhaustively. Designs are broken out by model (LT, RH, LoneStar), headlight type (halogen vs LED), and configuration (with or without integrated turn signals, low-beam wiring variations, sunshade, etc.).

You will find circuits for:

• Headlights (HAL-125, HAL-113, LED-125, LED-113) in all INT/LOWW combinations
• Directional signals / turn lights with headlights
• Marker lights, clearance and identification lights
• Fog lights (including LED white)
• Beacon / strobe lights
• Park lights with marker interrupt (10-pin and 4-pin clockspring)
• Backup / reverse lights for manual, UltraShift+, Allison, and TC10 applications
• Work lights (LED and customer-supplied) with switch packs, remote key options, and auto/manual reverse logic
• License plate lights, modesty lighting (day cab and sleeper), and skirt lights
• Interior lighting: dome, floor/search, reading, task, cabinet, courtesy, panel backlighting, and accent/mood lighting

Each design shows power feeds, grounds, switch logic, and how the Lighting Control Module interacts with the circuits. This level of detail eliminates the usual trial-and-error when a marker light or reverse light fails on a specific truck configuration.

Safety-related circuits demand accuracy. The manual provides complete ABS implementations for both Bendix and Wabco systems in 4-channel and 6-channel configurations, with separate designs for LoneStar and LT/RH trucks.

Additional coverage includes:

• Traction control (Bendix and Wabco controllers, with and without electronic brake)
• Wabco Full Stability Control
• Hill Start Aid (Bendix and Wabco)
• Park brake controls (with and without ECM, with gauge control)
• Service brake pressure and switch circuits
• Collision Avoidance System (warning)
• Lane Departure Warning systems (Bendix Fusion, AutoVue, Mobileye pre-wire, Wabco OnLane) with and without Qualcomm Safety Direct
• Adaptive Cruise Control (Wabco and Bendix, with and without display)
• Trailer ABS interface circuits (multiple configurations including center pin, BOC, EOF, TRAMEC)

When you are diagnosing an ABS light, a stability system fault, or a trailer communication issue, these diagrams show exactly how the modules are powered, grounded, and networked.

Driver comfort systems are fully documented, including both standard HVAC and the various no-idle options that fleets increasingly specify.

You will find complete circuits for:

• Front HVAC (auto temp control and standard) for A26 and X15
• Rear HVAC / sleeper systems (deluxe and premium)
• Bergstrom no-idle heat and cool with condensation management (2-switch and 4-switch versions)
• Espar no-idle heater
• Webasto Smartemp and standard no-idle heaters (with and without Swift)
• TRI-PAC no-idle APU
• Sleeper fan and bunk circuits

These diagrams include compressor, blower, and control logic as well as how the systems interact with the main electrical architecture. Useful for both repair and for verifying that a no-idle system is correctly integrated.

Modern trucks carry extensive telematics and monitoring equipment. This manual documents the factory wiring for a wide range of systems so you can install, repair, or troubleshoot them correctly.

Telematics coverage includes DriverTech (day cab and sleeper with J1939), Omnivision, PeopleNet / PMG (with and without DVR), Qualcomm IMCT and TMCT (multiple configurations with MVPC and panic button options), MCP50, MCT with and without Tracs, Tripmaster, Xatanet (J1708 and J1939), and OCC systems. Panic button and remote keyless access circuits are also included.

Instrumentation and monitoring sections cover instrument cluster (premium and standard), bulb check, request and status messaging, auxiliary gauges (primary and secondary), engine oil level and pressure, fuel economy and idle usage, transmission oil temperature, axle temperature (single and tandem), DEF economy, voltage monitoring, and high exhaust system temperature (HEST). Vehicle Information Display (VID) circuits with and without Bluetooth are also present.

If a fleet is adding or repairing a specific telematics platform, or if a gauge or monitoring function is not working, the exact power, ground, and data circuits are mapped.

Emissions systems are tightly integrated with the engine and electrical architecture. The manual provides Selective Catalytic Reduction (SCR) circuits for both A26 (ICT) and X15 applications, along with regen switch logic (including monostable and bi-stable inhibit switches).

Supporting circuits for aftertreatment power distribution modules, water-in-fuel sensors (Davco and Racor, with and without heaters), and related monitoring are also included. These diagrams are essential when diagnosing DEF system faults, regen issues, or aftertreatment-related fault codes that require verification of wiring and sensor power.

Accurate power and ground information prevents the most common diagnostic mistakes. This manual includes complete power distribution module (PDM) charts and diagrams for interior, underhood, sleeper, and aftertreatment PDMs, plus battery feed and key-switch circuits.

Ground and splice pack documentation is extensive:

• Ground splice packs 1022, 1023, 1027
• Powertrain ground and ZVR splice packs (6702, 6703, 6704)
• Forward and rear chassis splice packs (8800, 8802, 8803, 8804)
• Sleeper ground splice packs
• Interior dual post ground stud and various other splice locations

You also get battery configurations (including 3700 CCA packs), alternator circuits for Bosch, Delco Remy, and Leece-Neville units in multiple amperage and Delco/Mitsubishi variants, starter and crank inhibit logic (with hood switch options), and battery disconnect circuits. These pages turn “check the grounds” from a vague instruction into a precise, location-specific procedure.

Beyond the major systems, the manual covers a wide range of options and supporting circuits that appear on real-world trucks:

• Power windows, power door locks, heated and power mirrors, remote keyless access
• Seats (climate-controlled, RolTek hard-wired variants) and seatbelt reminder systems
• Fifth wheel slide, jaw monitoring, and jaw unlock control
• Axle loading (weight) monitoring, driver-controlled locking differentials (Dana and Meritor), height control, and rear axle load distribution
• Fuel level, water-in-fuel, and fuel heater circuits
• Engine block, oil, and fuel heaters
• Windshield wipers and washers (with low-fluid sensors)
• Radio and speaker systems (Bluetooth, amplifier, steering wheel controls)
• Auxiliary power outlets, cigar lighter, USB, and DC/AC inverter circuits
• Body-builder lighting blunt cuts and power modules
• Auto start-stop systems for automatic and manual transmissions
• Diagnostic connectors (9-pin green) and various interface connectors

This breadth means the manual remains useful even on trucks with uncommon option packages or body-builder modifications.

Navistar International® LT • RH • LoneStar
Schematics Manual

The complete electrical and electronic schematic set for International LT, RH, and LoneStar series trucks equipped with Cummins X15 or A26 engines. Every circuit, every connector, every splice pack — organized for real-world diagnosis and repair.

Stop Guessing. Start Diagnosing with Confidence.

When a LT, RH, or LoneStar truck comes into the shop with an electrical fault, the difference between a quick repair and hours of wasted time is almost always the quality of the schematic. This manual delivers the full factory-level wiring diagrams used by International dealers and fleet technicians.

You get every major system — Body Control Module, powertrain networks, lighting, ABS, HVAC, telematics, aftertreatment, and dozens of optional configurations — mapped with clear connector callouts, splice pack locations, and power distribution. Whether you are chasing a no-start, a communication fault on J1939, a lighting issue, or a complex telematics install, the circuits are here.

This is the reference that lets experienced technicians move faster and gives less-experienced techs a reliable map instead of trial-and-error. Instant download means you can have it open on a laptop or tablet at the truck before the next job rolls in.

Body Control Module & Communication Networks

Powertrain, ECM & Transmission Circuits

Lighting Systems — Exterior & Interior

Brakes, ABS, Stability & Safety Systems

HVAC, Comfort & No-Idle Systems

Telematics, Monitoring & Instrumentation

Aftertreatment, Power Distribution & Supporting Systems

Built for People Who Actually Work on These Trucks

This schematic manual is used by independent shops, fleet maintenance departments, dealer technicians, and mobile mechanics who need accurate electrical information without waiting for dealer-only resources or incomplete online fragments.

It is especially valuable when you are diagnosing intermittent electrical or communication faults, working on modified trucks, verifying repairs, training technicians, or servicing a mixed fleet of LT, RH, and LoneStar trucks with both X15 and A26 engines.

Because it is a searchable PDF, you can open it on a shop computer, laptop, or tablet, zoom into a specific circuit, and print only the pages required for the job.

Get the full 3,013-page Navistar International LT, RH, and LoneStar Schematics Manual (0000018825) as a clean, searchable PDF. Download immediately after purchase and keep it in your shop reference library for years of use.