2005 F150 4.6L 4x2 XLT (I believe the build date is prior to 11/2004)
ABS Code C1230

I've replaced the rear speed sensor and examined the wiring from the pigtail to the wiring harness and find no obvious damage.

Is the next step a rebuild of the ABS module? I've not found a source for new modules. Any other things to try that I've not listed?

 

Here are some tests you can try.

 

Awesome, thank you!

I may have overlooked them, but can you confirm resistance values for E3 and voltage values for E5?

 

I cropped those off by mistake.
E3: 5 ohms or less
E5: less than 9 volts

 

I was getting short to power on both rear ABS sensor circuits and finally traced the problem to the wiring harness connector that sits at frame level below the drivers side door. The connector had water inside and looks to have been shorting. I used some electronics cleaner and then a liberal amount of dialectric grease when reconnecting and the ABS light cleared itself.

Thanks again for the troubleshooting guide - it was a tremendous help!

 

Glad to hear this. Feels good to fix it yourself.