Trailer Brake Controller Help

Hello to all on Tundras.com,

We are an aluminum truck bed manufacturer and recently picked up a low mileage 2011 CMSB Grade 5.7 4x4 for research and development (read: to play with). Long story short, the previous owner/their mechanic did some less than stellar repairs. After fixing their uh-oh's, it was time for the fun stuff i.e. Optitron gauges, drive monitor switch, ultimately leading to a front end conversion. Upon installing the drive monitor switch, it was discovered that 2 wires from JL1 to J28 were needed and subsequently installed using the correct pins for the harness connector. Finished the job, go to start truck and.............nothing. Not even a click. Literally followed every single starting procedure/wire checking continuity and signal all the way from the ignition to the ECU, all good. Starting relay, good. Battery, new and good. Assuming that I crossed or damaged something while pinning the harness for the drive monitor switch, I located a Tundra at a junkyard and went and picked the entire J28 down to the JL1 with the drive monitor switch wires already present! Also pulled the starting relay as a test/backup. Spliced the entire new J28 and JL1 connectors into our truck, plug everything back in and.............nothing. No start, same condition. Now to the fun part, while installing the 2 wires the first time, we un-installed an aftermarket trailer brake controller installed by the previous owner. Figuring we had nothing else to lose or try, we plugged the trailer brake harness back into the truck and BAM, fires right up. Unplug it, same no start condition. Called the manufacturer of the brake controller and talked to three separate tech support persons and none had any idea why this would be the case!

Therefore, here we are, any Tundra experts out there know why the truck would not start without an after market trailer brake controller harness plugged into the factory connector?

Thank you in advance for your best guesses!

AlumBody Team

 

Wow, that's some strange behavior! You may get some responses in here, but you'll have much better luck if you post your story/question in the following thread:
https://www.tundras.com/threads/ask-the-toyota-mechanic.2404/

And if you don't already have a complete set of wiring diagrams, you can get those here:
https://www.tundras.com/threads/ultimate-wiring-diagrams-collection.81448/

 

Thank you Bakershack for the correct thread to post this as well as the link to the EWD's. I am sure we will be back with more questions soon!

AlumBody Team