Manitou MLT 735-120 electro-hydraulic problem

[Ian Stan]

Hi all
Got the Manitou out and wanted to drop the forks and attach a bucket . The thumb roller switches that control the carriage lock and the telescope function are dead as a doornail. Had the joystick apart and no sign of a burn on the pcb. Also can't find a fuse or relay mentioned, so suspect some sort of hydraulic control unit relating to both functions or a chewed wire leading to it . All sugestions gratefully received.

 

[Tom8400]

There is a switch that will stop those two functions, I had a lose wire on that it’s the orange hydraulic logo switch.
Worth a look

 

[ACEngineering]

Hi all
Got the Manitou out and wanted to drop the forks and attach a bucket . The thumb roller switches that control the carriage lock and the telescope function are dead as a doornail. Had the joystick apart and no sign of a burn on the pcb. Also can't find a fuse or relay mentioned, so suspect some sort of hydraulic control unit relating to both functions or a chewed wire leading to it . All sugestions gratefully received.

AGE would be helpful

 

[ACEngineering]

There is a switch that will stop those two functions, I had a lose wire on that it’s the orange hydraulic logo switch.
Worth a look

no it only stops the aux, nothing cuts out the extension other than the switch that cuts everything off

 

[ACEngineering]

Hi all
Got the Manitou out and wanted to drop the forks and attach a bucket . The thumb roller switches that control the carriage lock and the telescope function are dead as a doornail. Had the joystick apart and no sign of a burn on the pcb. Also can't find a fuse or relay mentioned, so suspect some sort of hydraulic control unit relating to both functions or a chewed wire leading to it . All sugestions gratefully received.

fuse is labeled LSU, very top of fuse box. 2 fuses in seperate holders a 20amp for starter and i think its a 5amp for LSU joystick.

 

[Ian Stan]

Thanks guys , it's not the 3A fuse mentioned. And the hydro switch only locks the carriage not the telescope ram

 

[ACEngineering]

Thanks guys , it's not the 3A fuse mentioned. And the hydro switch only locks the carriage not the telescope ram

if it has the 2 big square type solenoids for aux and extension then look at the 4 pin plug on one of them and with a tester see that you have a 12volt feed from the fuse, and then an earth, (the other wires are a 5volt output to joystick switch and then a variable voltage back to solenoid 0.5volts to 4.5volts)

If its the later type small round solenoids one each side of spool rod then they work differently and i would need to look in a book for that.

( this is why i asked for age, 2010 is when the change over period)

If the power feed is getting to solnenoid valve and it has earth then you need to look at the hyd pilot pressure supply, inline filter near main return filter and 2 pipes going in to solenoid valve, one is return the other is the feed in. remove the feed in pipe and the male male adaptor and up inside the block is a hidden small gauze filter.

 

[Ian Stan]

Thanks for your help. The machine is 08 reg. So I'm guessing the earlier type

 

[Ian Stan]

Where is the solenoid situated ?

 

[ACEngineering]

Where is the solenoid situated ?

back right hand corner of cab, accessed from inside the cab BUT you may need to go on the out side to locate the electric plugs. depends how they routed them in factory and what cable ties they used.

 

[Ian Stan]

 

[Ian Stan]

 

[Ian Stan]

 

[ACEngineering]

if they have black paint on them solenod valves then they are original which is nothing short of a miracle they are common to fail although in your case unlikely to fail both at exactly the same time.


You do have a vermin problem though, all that crap under them plastic panels bits of chewed up paper etc vermin love to make nest under that plastic side pod and chew wires there along with the foam insulation.

 

[Ian Stan]

Oh there's certainly mice in there , no doubt , and that was my suspicion unfortunately no evidence of a chewed wireanywhere I've dug out yet. As you rightly say unlikely both services would fail together i suspect a common denominator with sharp teeth. But I know now where to look . Thanks

 

[Ian Stan]

these were chewed off and shorting . Joining the thin and thick blacks (obvs earths) allows the two services to work

 

[Ian Stan]

Theres a spare bare plug nearby .... but if it had been chewed off the other half of the plug would still be attached .... i'll see if i can find it