After a day of checking things out, still not working. Took it for a test drive and still the same as before. The brakes on the rear axle are new and maybe they need a few miles to burnish them.
- checked all pos & neg connections and ground points to the frame on TT.
- few years ago I installed a shunt in the pos. from the battery near the converter for an ammeter but never mounted the meter. Removed the shunt.
- replaced the breakaway switch because it appeared to have corroded contacts and voltage wasn't what it should have been.
-replaced battery in the truck.
Pulling the breakaway switch appears to be making all 4 wheels brake okay and voltage is good at 12.4 - 12.5 volts.
The menu on the P3 is still saying output voltage is zero and current is only about 0.5 amp. The input voltage from the brake pedal is fluctuating quickly between about 12.5 & 14 volts. Maybe the switch needs replacing? Checked the wiring connections again between P3 and GM wiring and looks okay.
Think I'm just going to take it into the hitch shop and maybe they can figure it out quickly.
