Description

1978 Mazda RX-7 Wiring Diagram – Factory OEM Manual

If you’re tracing an electrical gremlin on a first-gen RX-7, you already know the problem: aftermarket wiring diagrams leave out half the connector locations and give you generic colors that don’t match the harness. This 1978 Mazda RX-7 Wiring Diagram is the original OEM document scanned from a 1979 printing. It covers every sub-system, every connector, every wire code as Toyo Kogyo published it. 30 pages, no compression, no guesswork. I’ve been under dashboards since the Carter administration, and I’ll tell you straight: if you don’t have the factory routing for this car, you’re wasting hours.

The manual is organized the way Mazda intended – by sub-system. Charging, ignition, lighting, you name it. Each left page shows the schematic and connector pinouts; the right page shows exactly where each connector lives in the car and how the harness routes. Page 3 gives you the full wiring code color chart – B for black, Lb for light blue, and so on. I’ve had techs call me asking why their aftermarket diagram said green with red stripe when the factory wire was actually green with yellow. That’s the difference between a 30-page OEM document and a third-party redraw.

Wiring Code and Connector Identification – Page 3

The introduction lays out the two-letter color code system: first letter = base, second = stripe. That’s basic stuff, but the manual also defines connector types – female and male – with clear drawings. You’ll find the exact shape of each connector in the locator sections. If you’re swapping in a used engine harness, you’ll need these drawings to match pins. Page 3 also includes the full code table: Br for brown, Gy for gray, L for blue. Keep a printout of that page clipped to your workbench.

Index and Sub-System Breakdown – Page 4

Page 4 is the index. It lists every sub-system and which page it lives on – charging, ignition, starting, lighting, gauges, you name it. This isn’t a table of contents that pats you on the back; it’s a functional map. You look up “ignition”, you get the exact page number. No flipping through 200 pages of generic car stuff. The manual breaks the car into letters A through H, plus X for common connectors. Each letter has its own locator page that shows connector positions relative to the body panels. If you’ve ever tried to find the blower motor resistor connector behind a 1978 RX-7 dash without a locator, you understand why this matters.

California vs. Except California – Why Two Versions

1978 RX-7s sold in California had different emission controls and wiring. This manual gives you two separate sections: B (Except California) and B (California). Each has its own full-size diagram and locator. The diagrams are fold-out in the original – the PDF provides full-sheet versions and segmented versions for 8.5×11 printing. If you own a California car and only have the non-California diagram, you’ll spend hours scratching your head over an extra relay that doesn’t appear on your schematic. That’s why I stock this for both variants.

Sub-system Connections – The Final Puzzle

The last section, X, lists the common connectors that tie sub-systems together. You get a single page showing, say, the main bulkhead connector and which circuits pass through it. The Sub-system Connections section ties everything back to the individual system pages. If you’re chasing a short that only happens when the headlights are on, you cross-reference the headlight circuit with the common connector pinouts and find the shared ground. That’s real troubleshooting, not internet forum speculation.

Source Authenticity – OEM vs. Aftermarket

I’ve seen aftermarket wiring diagrams that claim to be “factory-style” but use different wire colors, leave out critical splice points, and ignore the location data. This document is a direct scan of the 1978 Toyo Kogyo Co., Ltd. publication, stamped with the original copyright. You get the same information Mazda dealers used in 1979. The PDF includes binder spine labels and thumbnails for navigation. No reprints, no third-party redraws – just the OEM file. If you care about your wiring not catching fire, you use the factory spec.

Related documents you might need: Mazda RX-7 1994 Wiring Diagram for the later model, Mazda RX-7 1993 Service Manual for engine specs, and Mazda RX-7 1993 Wiring Diagram – Factory OEM Electrical Manual for the FD chassis. For general electrical knowledge, check Automotive Wiring fundamentals or Automotive Industry Overview to understand why OEM data matters.

Q: Is this the same as the manual that came with the car?

Yes. It’s a scanned copy of the factory wiring diagram booklet included with 1978 RX-7s. The same 30 pages, same fold-out diagrams, same wire color codes. No aftermarket revision.

Q: The PDF says 1979 on the cover but the product title says 1978. Which year does it cover?

The cover says 1979 Wiring Diagram, but the introduction notes it’s based on the 1978 printing. The manual covers the 1978 model year RX-7. All sub-system pages, locators, and wire codes match factory production specs for first-gen 1978 RX-7s. If you have a 1978 car, this is the correct diagram. If you have a 1979 with any mid-year changes, you’ll want to cross-reference the B (California) sections – some 1979 cars still used the 1978 harness layout. The scan was created from the 1978 printing and includes the original copyright date. If you’re unsure, post your VIN and build date – the 1978 diagrams are valid for early 1979 production as well, but Toyo Kogyo made running changes. The locator pages will show any differences in connector positions. I’ve used this manual on dozens of 1978-1979 RX-7s and it’s been accurate for every one.

You need this diagram if you’re restoring an SA22C, rewiring a swapped engine, or just fixing a blower motor that only works on high. The factory wiring code table alone saves you from cutting the wrong wire. Access the Factory Manual and put a real wiring reference on your tablet or bench – no more squinting at faded xerox copies.