Electrical Wiring Diagrams, Connectors and Terminal Numbers

Not exactly a novice to electrical wiring diagrams and such, my 2023 Tacoma and Toyota threw a curve; Short-story long:

Connectors are male or female housings (sexist terminology, I know) with metal connections known as terminals. Connector housings derive their "sex" from the type of terminals that they hold. so, a "plug" that houses female terminals is a female connector.

The terminals are usually numbered by looking at the mating face of the fixed or mounted housing, having the latch on the top, then count rows left to right and top to bottom, as if reading from a page.

Therefore, the wire harness end of a loose plug attached to a fixed connector may be "read" in a similar fashion, by rows: upper left to lower right. "UON", unless otherwise noted.

Reviewing TIS connector data to investigate the 22-position Delphi brand plug (EB5) in the engine compartment Fuse/Junction Box, it was noted that the actual plug was marked to indicate Position #1: upper left. Positions #11, #12 and #22 were marked by Delphi to suit, so, no mistake.

The layout in TIS for EB5 conveniently showed the plug and also the receptacle with numbers transposed to match.

Now, TIS provides wire colors and advises that some may be different depending on systems or accessories. Finding more mismatches than matches, it was discovered that both the plug marking and TIS data were reversed!

After a bit of research, Tacoma Technical Training 223, Appendix explained:

"The EWD (electrical wiring diagram) view of connectors only shows the face view.
Location of pins and wire colors can be identified, but all the locations must be transposed to
the wire harness side of the connector for proper T-pin placement."
Further,
"The Terminals of ECU charts appear only in the Repair Manual – not the
EWD. Wire numbering and locations are shown for the harness side of the
connector and all connectors used on the ECU are shown in actual location."

So, Short story long: The Delphi connector terminal marks were ignored by Toyota and the TIS data (which appears to match the connector) must be transposed to be correct when viewed from the wiring harness!



Note the Pin#1 and #11 locations indexed on the connector.