Description

Unknown EF, EC, TB42E, TD42, TB42S Wiring Diagram – 130 Pages of Factory Electrical Data

You’ve got an engine that won’t fire, a preheat system that’s dead, or a wiring harness that looks like a rat’s nest. Before you start poking around with a test light and guessing, you need the actual factory wiring diagram. I’ve seen too many DIY guys fry an ECU because they used a haywire aftermarket schematic. This 130-page document covers the Unknown EF, EC, TB42E, TD42, TB42S Wiring Diagram — the kind of stuff you find in Nissan Patrols and other off-road rigs. Period.

130 Pages of Factory Wiring Data

That’s 130 pages of OEM electrical schematics, component locators, and pinout tables. The manual covers four distinct engine families: EF/EC (likely the earlier injection control), TB42E (4.2L petrol inline-six), TD42 (4.2L diesel), and TB42S (a variant of the petrol six). Each engine gets its own supplement section with dedicated wiring diagrams. The binder-style layout means you can flip directly to the engine you’re working on without wading through irrelevant pages. Page 1 shows the preheating and EGR system schematic for the RD28T — a reference point for the whole glow-plug circuit.

EF & EC: What’s in the Preheating Section?

The OCR excerpt from page 1 shows the “SYSTEME DE PRECHAUFFAGE INSTANTANE ET SYSTEME EGR” — instant preheating and EGR control. Follow the lines from the battery through the fusible links, ignition switch, glow-plug relay, and temperature sensor to the ECU. Note the four 1.5A fuses inline; if you lose a preheat cycle, those are the first things to check. The diagram also includes the vehicle speed sensor input and the tachometer feed. If your glow plugs aren’t cycling, trace the circuit with this schematic before replacing parts.

TB42E, TD42, TB42S – Spot the Differences

Each of these engines has a distinct fuel and emission control system. The manual separates them into Supplements IV, VI, and VIII. For example, Supplement VI (pages EF & EC-6002 through EF & EC-6025) specifically covers the TB42E and TD42 with their own “SYSTEME ENTIER DE COMMANDE DU MOTEUR ET DE CONTROLE ANTIPOLLUTION” — full engine management and emission control wiring. The TB42S supplement appears in Supplement VIII (EF & EC-8017). If you’ve got a Patrol with a TB42S, don’t try to use the TB42E diagram; the pinouts differ. Page 2 of the manual lists the exact supplement pages for each engine code.

Why OEM Wiring Diagrams Beat Aftermarket Hand-Drawn Schematics

Aftermarket wiring diagrams are often redrawn by someone who never laid hands on the actual harness. They drop ground points, merge connector pins, and guess at wire colors. This manual is a direct scan of the factory binder — possibly Nissan’s own service material for the RD28T and related engines. The wire colors are printed next to each line, the connector shapes are drawn to scale, and the component locations reference specific spots on the vehicle. If you’ve ever spent an afternoon chasing a short because a third‑party diagram showed a 12V wire where it should be ground, you’ll appreciate the precision. Don’t use aftermarket for electrical work. Use this.

Using the SDS Table for Tune-Up Specs

“SDS” in the table of contents stands for “Caractéristiques et valeurs de réglage” — specifications and adjustment values. These pages list injection pump timing, glow plug resistance, idle speed, and other tune‑up data. For the TD42 diesel, you’ll find the injection timing in degrees; for the TB42E petrol, the ignition timing and dwell angle. The SDS section is where you go after you’ve fixed the wiring but the engine still runs rough. Always pull those numbers before turning a screw. A factory SDS is not a Haynes approximation.

Does this manual cover the RD28T engine?

Yes. The RD28T preheating and EGR system is covered on page 1.

What if I have a bilingual French/English manual – can I still use it?

The schematics use international symbols and color codes, so language isn’t a barrier. The component labels are in French, but a quick translation or a look at the diagram will tell you what’s what. I’ve used French diagrams for years without speaking a word of French. What matters is the wire colors and connector numbers, which are universal. This manual also includes English headings in the TOC, so you can navigate. If you get stuck, search for the component name in French online.

Stop tracing dead ends with third‑party drawings. Get the real thing. Workshop Manual ETL10, Engine Electrical System (G4ED-GSL 1.6), and Toyota Mazda GM Wiring Diagram Manual 230 Pages are also available if you need related wiring data. For more background, check Automotive Wiring or this Wikipedia article on diesel engines. Access the Factory Manual from AutoRepairManuals and keep your engine wiring straight.