I have a 2012 Hino 268 in the shop with the common no power on take off and I believe i have found my issue. I started by changing the brake pedal switch and the 3 pressure switches on the service brake relay and parking brake relay valves, well that didn't fix anything, So i went back under the truck and checked for voltage at the switches and i have 0.45 volts at the service brake relay switch and 11.8 on the parking brake relay switches. So to test my theory i made a jumper and ran power from one of the other switches and my problem went away. So after following the wire which shows to be a red with black stripe it seems to go over to the ecm mounted on the side of the engine on the left. I have checked all the wiring to the switch and it all checks out ok. So my question is what supply's voltage to that switch? is it the ecm or another switch somewhere that i cant see on Mitchell. Thanks
2012 hino 268 question on service brake pressure switch problem
- Thread starter Cris
- Start date
The power comes from the U2 fuse, and yes you should have 12v on one leg and the other leg goes eventually to the ecu on the ground side. If you jumped 12v to the switch and it worked then I would say your issue is on the power side not the ground side. It goes through the pass through connector, the connector on the rh side of the frame with the white lock behind the pass side a foot or so. And a few others. Usually the wire breaks off right near the connector. Check All fuses first. Sounds like you are close. Just got to systematically eliminate ech leg until you find the bad section of wire.
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Ok that makes some sense as to why it ran to the u2 ecu now, I spent almost a hour following the harness the best i could through 3 connectors, and ended up at the junction box there on the right side, where it looked like it went to a grey connector and then just passed right back out and went to the ecu. Now that i know it goes to the U2 fuse i can start there and follow it out to the different areas. Another question i have is, What is J/C Signal? is that junction connector or something?
Well after looking at all the wiring, i went to the 5 amp fuse and sure enough it was blowed. Im thinking the sensor may have shorted out and thats what blew the fuse, or maybe it was blown at the other shops its been to for this issue. replaced the fuse and plugged everything back in and the issue was fixed. Thanks for the help guys.
Glad you found it. First rule of Hino is check EVERY fuse and make sure EVERY fuse is accounted for.
