Jaguar XJ8, XJ8L, XJR & Vanden Plas 1998 Technical Guide (P/N JJM 18 15 12/80)

Jaguar Cars Limited’s V8 XJ Series Sedan Technical Guide, P/N JJM 18 15 12/80, August 1997, introduces the 1998 XJ8, XJ8L, XJR, and Vanden Plas. The equipment tables distinguish US, Canadian, and Mexican specifications. The XJ8L is US-only, and the Mexican lineup excludes the XJR.

PDF Bookmarks and Diagram Readability

Navigation and diagram labels: Embedded bookmarks link to chapters and subsections. PDF text search is unavailable. The network and relay diagrams are legible, with zoom helpful for smaller labels and reference numbers.

The download is one printable English-language PDF. Its 110 pages include 102 numbered content pages, two cover and title pages, one preface page, four notes pages, and one closing publication page.

AJ-V8, Chassis, and Electrical System Changes

This selection of topics highlights the major system changes. The guide also covers the new paint-code format and revisions to the in-car audio system.

• AJ-V8 engines: Naturally aspirated and supercharged engine construction, valve timing diagrams, Eaton M112 supercharger operation, and engine specification tables.

• Fuel and emissions: Single- and twin-pump fuel delivery, on-board refueling vapor recovery (ORVR), evaporative emission control, and exhaust gas recirculation (EGR) on applicable SC models.

• Cooling and lubrication: Intercooler circulation, SC coolant pump and radiator changes, engine oil cooling, and cooling-fan switching points.

• Transmission and driveline: 5HP24 and W5A580 installations, electronic shift control, limp-home behavior, driveshaft changes, and the 14HU final drive.

• Chassis: Front and rear suspension changes, adaptive damping, ABS hydraulic modulator integration, and identification of Sport and Comfort variable-ratio steering racks.

• Electrical systems: CAN, SCP, and ISO 9141/2 network diagrams, harness layouts, fuse and relay identification, and immobilizer operation.

• Occupant protection: Side airbags, pyrotechnic front seat belt pretensioners, side impact sensing modules, and single point sensor diagnostics.

Jaguar prepared this guide for dealer workshop personnel reviewing the model-year changes. Repair and servicing procedures are in the separate Service Manual.

AJ-V8 and Supercharger Differences

The valve timing diagrams show how the NA engine’s variable valve timing differs from the SC engine’s fixed intake-cam sprockets. The SC engine also uses different pistons, head gaskets, and a revised timing cover.

The Supercharger System Schematic shows the Eaton M112, bypass valve actuator, and twin intercoolers. The Engine Control Module (ECM) section explains the SC engine’s narrower misfire-monitoring range and the protective limits it applies when it detects a coolant-pump relay or second fuel-pump relay fault.

Fuel Delivery and Exhaust Variants

The guide explains when the ECM brings the SC engine’s second fuel pump online and how the ORVR system routes vapor during refueling. A check valve in the filler neck prevents the tank from being fully drained through a siphon tube.

The exhaust section distinguishes the flanged front-muffler connection on the XJR and Vanden Plas from the slip joint on the XJ8 and XJ8L.

Intercooler Cooling and Engine Lubrication

The Cooling System Schematic – 4.0 Liter SC identifies the intercooler radiator, coolant pump, and dedicated fill and bleed points. The lubrication section explains how a thermostat-controlled diverter valve routes oil through the SC engine’s oil cooler.

Transmission Controls and Reference Data

The W5A580 section describes the valve block, dual linear selector switch, reverse-gear selection, and limp-home operation. Its technical data includes the specified oil type, approximate oil volumes, and gear ratios.

The 5HP24 discussion focuses on sedan installation and control changes and points to the separate AJ-V8/5HP24 and XK8 technical guides for further detail. The mode switches for the two transmissions look alike but are not interchangeable.

Body, Steering, and Climate Control

Body coverage explains the revised suspension supports and dashboard mounting, along with high-strength steel reinforcement for side-impact resistance. Color-coded identification plates distinguish the Sport and Comfort steering racks.

Climate-control coverage describes the revised refrigeration hardware and heater circulation. It also explains how the Air Conditioning Control Module (A/CCM) operates the heated windshield where fitted and the heated door mirrors.

Hood-latch repair: The latch screws form threads in the plastic housing. Cross-threading the screws during reinstallation can damage the housing.

Electrical Networks, Immobilizer, and SRS

Separate NA and SC network diagrams show how the powertrain and body modules communicate. The Harness Layout, Fuse Box and Relay Locations, and circuit assignment tables help technicians identify a module and its power supply before electrical repair. The illustrations cover system connections and component locations. Connector pinouts and individual wire identification require a separate wiring reference.

The guide explains the revised lighting and body functions of the Body Processor Module (BPM) and Security and Locking Control Module (SLCM). It also describes how the Key Transponder Control Module (KTCM), BPM, and ECM authorize cranking, ignition, and fueling.

Jaguar identifies its Portable Diagnostic Unit (PDU) as the tool for replacement-key programming and SRS fault retrieval. The SRS section explains how the single point sensor logs faults and triggers the warning lamp or backup audible warning.

High-pressure fuel systems and heavy driveline components require the applicable workshop safety precautions. The occupant-protection section also addresses handling precautions for airbags and pyrotechnic pretensioners.

Sample Valve Clearances and Transmission Oil Volumes

The engine specification table lists the same cold valve clearances for the NA and SC AJ-V8. Intake clearance is 0.18–0.22 mm and exhaust clearance is 0.23–0.27 mm.

The W5A580 technical data lists approximately 9.4 liters of oil for the transmission alone and 10.0 liters including the oil cooler.