Cummins ISB & QSB5.9 Electronic Troubleshooting & Repair Manual, 1999 (P/N 3666194-01)

The Cummins Troubleshooting and Repair Manual — Electronic Control System, ISB and QSB5.9 Engines, Volume II covers electronic fault diagnosis and in-chassis repair decisions. This is the May 1999 printing, copyright 1999, P/N 3666194-01, identified as the bulletin number on the publication page.

PDF Bookmarks, Diagram Detail, and File Contents

Fault-code navigation and diagram detail: Embedded bookmarks provide access to the introduction, individual fault-code sections, and index. PDF text search is not available. Small connector and pin labels require zooming.

The ZIP contains one printable, English-language PDF with 507 pages, including the cover, publication details, foreword, contents, safety pages, notes/blank pages, and index.

Electronic Fault Isolation and VP44 Diagnostics

The following selected coverage highlights outline the main diagnostic areas. Other entries address engine overspeed and loss of power to the ECM’s real-time clock.

• Fault-code troubleshooting: Provides 60 step-by-step fault-isolation trees covering 78 fault codes, plus six information-code entries with direct corrective guidance.

• Speed and throttle inputs: Engine and vehicle speed sensors, accelerator and remote throttle circuits, pedal calibration, idle validation, and auxiliary speed or pressure inputs.

• Pressure, temperature, and level sensors: Oil pressure, coolant temperature and level, intake manifold pressure and temperature, fuel temperature, water-in-fuel, and OEM pressure circuits.

• VP44 fuel-system diagnosis: Pump-internal failures, lift-pump circuits, fuel-metering and shutoff faults, power relays, datalink communication, commanded timing, and pump-to-engine synchronization.

• OEM outputs and control features: A/C clutch, exhaust brake, fan clutch, intake-air-heater relays, switched droop, alternate torque-curve selection, dual-output drivers, and transmission shift modulation.

• Illustrated test support: ESS supply/signal/return, shared sensor supply, VP44 pump/ECM datalink, unswitched battery supply, dual-output driver, and transmission shift modulator diagrams, with connector and ECM pin-location views.

Written to guide a service technician through logical fault isolation, this manual is suited to technicians and experienced engine or equipment owners who are comfortable using INSITE, a multimeter, connector test leads, and OEM wiring information.

Fault Codes, Sensor Circuits, and INSITE Checks

Diagnostic entries identify PID/SID, SPN, FMI, warning-lamp status, reason, and effect. Circuit descriptions, component locations, and “Shop Talk” notes explain the system before troubleshooting summaries lead into numbered tests.

The charts cover connector inspection, supply and signal checks, sensor resistance, continuity, shorts to ground, shorts between pins, ECM output checks, repair or replacement decisions, and final code verification and clearing with INSITE.

The shared sensor-supply tree explains that the engine position, intake manifold pressure, and oil pressure sensors use a common ECM supply and return. The intake manifold and coolant temperature circuits also depend on that source. That relationship helps a technician interpret several simultaneous sensor codes before replacing individual parts.

VP44 Pump Faults and External Causes

The VP44 chapters distinguish Bosch pump-internal failures requiring pump service from external problems involving battery supply, relay operation, ground integrity, and ECM-to-pump communication.

Commanded-timing and synchronization entries also address inlet or outlet restrictions, static timing, and the engine-position reference signal. An active pump fault can deactivate the lift pump, so loss of lift-pump operation does not by itself establish that the lift pump has failed.

Test Equipment, Application Differences, and Repair Scope

Service aids: Named equipment includes INSITE, Cummins connector test leads Part Nos. 3822758 and 3822917, Weather-Pack leads 3823995 and 3823996, sensor breakout cable 3824775 from kit 3824773, and thermometer kit 3822666. Connector-matched leads are specified to prevent pin and harness damage during measurements.

Application differences: Power-supply diagnostics distinguish 12-volt and 24-volt systems. Notes address single- and dual-coil vehicle speed sensors, the Sterling two-pin coolant-level arrangement, and the illustrated 23-pin OEM interface. Some older ISB engines use a different OEM interface connector; Bulletin No. 3666195 is referenced for the matching wiring diagram.

Companion manuals: This volume focuses on electronic troubleshooting. Component and assembly rebuild procedures belong to the engine shop manual. Corrective branches refer to separate publications, including Bulletin No. 3666193 for VP44 and lift-pump replacement and several base-engine checks. Those companion manuals are not included.

Vehicle- or equipment-specific component operation, locations, and repairs are deferred to OEM service information, although this volume tests related OEM harness circuits up to the ECM interface.

Cummins cautions that unresolved active faults can damage a replacement ECM. Repair safety notes address battery isolation, stored capacitor energy, and system pressure; energized diagnostic tests have their own specified conditions.

Selected Speed-Sensor and Lift-Pump Resistance Specifications

The vehicle speed sensor test specifies 750 to 1500 ohms across each sensor-side connector’s coil, with the keyswitch off and the OEM harness disconnected.

Lift-pump resistance specifications distinguish 0.1 to 2.0 ohms for the 12-VDC pump from 0.1 to 4.0 ohms for the 24-VDC pump. These limits apply with the keyswitch off and the pump disconnected, after subtracting multimeter-lead resistance.