Activating Hydraulic jack blows fuse and stops extending

Disconnect wiring from the solenoid. Test solenoid conductors for any continuity to ground.
Check wiring to the jack down conductors for broken or pinch.
I will go to my rig and pull troubleshooting manual.

Mine is not 325 series. It is 200/210. so no help in manual.
325 service manual link
This manual is one of 325 series
ML13514 manual

Hi Bud, thanks for the manual links.... I found mine and it sounds like the solenoid is the problem.
When you say "Test solenoid conductors for any continuity to ground." Should there be continuity or not ? (I'm not very electrical :) )
Gerry

There should be no continuity to ground.

You can also ohm out the coil in the solenoid and compare it to a good solenoid. I can help you over the phone or maybe you can find electrical person to help you. There should be a specific ohmic value when you measure between the two leads that go into the solenoid. I have been a professional electrical electronic troubleshooter all my Life and I also suspect it’s the solenoid as well.

thanks I'll check it out tomorrow morning......

It is very rare for a HWH harness to have a short. The solenoid usually is the cause of the short. What usually burns out that solenoid is you have a jack that is sticking on retraction and the red down light does not go out. That means when in STORE, the light does not go out and that leaves the power to the solenoid. Those solenoids are momentary solenoids and should not have 12 volt power to them longer than 15 minutes. If the time limit goes over 15 minutes the solenoid coil overheats and shorts out. That is the purpose of those 15 amp fuses. To protect the HWH control box from this type short. Once the last Red jack down light goes out the power to the solenoids is turned OFF. Doug