Top critical review
Did not work as I would have thought for my vehicle.
August 19, 2018
I bought the tester to check the electric brake circuit on my Mercedes ML as the dealer provided no help. When I plugged in the tester with the vehicle and lights off, 3 LEDs came on right away. This isn't the way the instructions illustrate the operation of this tester. When the vehicle was started no change. The brake controller circuit LED did come on when the brake controller was activated, so I figured that did work. I know the lights work as my trailer lights respond as they should.
I ended up returning the tester as it didn't work as described for my vehicle. I noticed there is a similar tester 58271 and maybe that one will work for me. I haven't ordered it to try out.