rando said:I agree and that appears to be the case with the 4runner. The only caveat is that some parts require there own harness.
Example:
1) The wiring for the autodimming mirror isn't in the truck because that harness is used exclusively for the mirror. Leaving it out doesn't require Toyota to make a different harness. They just omit it completely.
2) Wiring for the light sensor isn't in the truck. Instead there is a junction block (fancy name for a connector) where the solar sensor and light sensor connect. For non Limited and non DRL models, only a 2 wire harness connecting the solar sensor to the j/b is in the truck.
And for what it's worth, the assumption is not strictly true. I've seen cars that DO have different harnesses based on trim levels. In those cases perhaps the harnesses had uses in other platforms that justified their existence in the manufacturers parts bin.
It's not uncommon to have different harnesses for different trim levels as some options are not available in certain levels so they can save money on manufacturing costs. Within the same level it all the harnesses should be the same as it's easier for the assembly line worker to grab an SR5 harness rather than a Limited but it would be alot harder for him to find the harness that has fog lights, but not the sunroof or the JBL but does have the nav system...
As for the autodimming mirror. It only comes standard on Limited models so all the wiring may be built in, but on the SR5 and Sport you need to splice in under the dash (there is no connector or junction block for it to connec to). Makes me wonder what a factory ordered SR5/Sport autodim harness looks like... or if they are all just port installed using the splicing method.