Where to find free wiring diagrams online?

You're in the right place actually — SpotOnAuto has the largest free wiring diagram library I've found. Over 148,000 diagrams covering most makes from 1982-2013. Check out the [wiring diagram library](/wiring) — search by year, make, and model. They have everything from headlight circuits to engine management to body control modules. Full color, zoomable, and you can download them. For newer vehicles (2014+), your options are more limited for free: - Some manufacturer websites offer limited free access (Toyota TIS is free for some info) - AutoZone's repair guides have SOME wiring diagrams - YouTube has people walking through specific circuits But for anything 2013 and older, the library here is honestly better than what I was paying Mitchell for.

The SpotOnAuto wiring section is legit. I used it last week for a power window circuit on my '07 Tundra and it had the exact diagram down to the connector pin numbers. Saved me a $35/month subscription. Also worth knowing: some public libraries give free access to Chilton's online, which includes wiring diagrams. Check your local library's website for database access.

For DTC-specific wiring, the [trouble codes section](/codes) here also cross-references the relevant circuits. So if you have a P0135 (O2 sensor heater circuit), it'll point you to the right wiring diagram. Pretty slick.