T5.120 brake issue

[robs1]

Our T5.120 won't release the pressure in the trailer brake valve. If the tractor is turned off the pressure seems to go and the tractors own brakes aren't on all the time so it seems the hydraulic oil that powers the trailer brakes isn't returning to the system as it should , any ideas ?

 

[Welderloon]

Check the trailer/tractor hyd coupling is functioning properly.
Had one recently where the QC was acting like an NRV & the brakes were taking an age to release after engaging fine, checked trailer brakes, return springs etc all good.
changed hose end on the trailer, no difference, changed the tractor coupler & the issue seemed to be resolved - put it down to wear - 2020 T6-180

 

[robs1]

Check the trailer/tractor hyd coupling is functioning properly.
Had one recently where the QC was acting like an NRV & the brakes were taking an age to release after engaging fine, checked trailer brakes, return springs etc all good.
changed hose end on the trailer, no difference, changed the tractor coupler & the issue seemed to be resolved - put it down to wear - 2020 T6-180

It was the brake light fuse blown, must be connected to the brake solenoid for some reason, not clever if you were flat out on the road and it blew and put the trailer brakes on full

 

[Lakesdigger]

It was the brake light fuse blown, must be connected to the brake solenoid for some reason, not clever if you were flat out on the road and it blew and put the trailer brakes on full

Better than no trailer brakes though

 

[robs1]

Better than no trailer brakes though

Possibly but still potentially dangerous

 

[Lakesdigger]

Possibly but still potentially dangerous

Yeah but a better failsafe than no brakes

 

[Spanner_Man]

Part of the TMR rolled out in 2018 when the fuse blows you don't get full pressure only around 10bar

 

[powerontheland]

Our T5.120 won't release the pressure in the trailer brake valve. If the tractor is turned off the pressure seems to go and the tractors own brakes aren't on all the time so it seems the hydraulic oil that powers the trailer brakes isn't returning to the system as it should , any ideas ?

Is the brake master cylinder spewing oil out?? I had a T6 a couple of years ago that had a crack in the trailer brake valve and was filling the master cylinder up with Multi G . Spewing it all over the exhaust, wonder it never caught fire. First symptoms were pressure in the trailer brake line.

 

[robs1]

Is the brake master cylinder spewing oil out?? I had a T6 a couple of years ago that had a crack in the trailer brake valve and was filling the master cylinder up with Multi G . Spewing it all over the exhaust, wonder it never caught fire. First symptoms were pressure in the trailer brake line.

No it was a blown fuse on the tractor brake lights for some reason, why that affects the trailer brake pressure I have no idea. We fitted new brakes to the tractor about six weeks ago but they have been perfect since then up to now, and all working fine this morning.

 

[Spanner_Man]

The fuse is connected to the pre brake part of the trailer braking system now, lights come on small pressure fed to brake valve