I dug out alot of battery corrosion when I checked cables but it was clean when I popped the last 2 new transistors. The customer has a really good weekly cleaning/watering schedule. All the batteries look new but there was alot underneath the battery pan

By any chance is the battery super corroded and has acid everywhere? I had a truck that had so much surface voltage it would cause shorts, until I ran the truck with the battery on the floor!

Yes, both diode blocks removed and disconnected. I ran the drive motor using by-pass and the directional contactors. The drive motor runs great. I also ran the hydraulic motor successfully.
I just got done checking the integrity of the insulation sheet under both transistor heat sinks. Ran 200volts (handyman) no leaks. I've decided to send this girl to the shop. Crazy

Really? The Selftest only closes contactors and looks for shorts it does send any amps through the system. This tells me you have a direct hard short!

You tested the diodes disconnected yes? Also of course you ensured they are 1 directions only?

Run the test with the traction Fuse out, see if it blows any thing, if it doesn't you know the issues is in the traction circuit!

Thank you Marco. I've checked just about everything. I ran both the hydraulic and drive motors. I've checked all 4 diodes (both blocks) with a Handyman. Checked all contractors and sent the main card out for testing and repair. I checked all power cables. The only thing that hasn't been checked yet is the rubber insulation sheet under the transistors. I mean I checked the heat sink for short to chassis with an ohm meter, but not with the Handyman. I know Clark's use to get pin holes in that sheet causing shorts. This thing is definitely a problem child. But thank you for chiming in. I already burnt up 2 new transistors. They blow on the self diagnostic check.

Nissans with this system are know to pop Transistor when a load is on them that is not normal, like pushing pallets of beer across the warehouse. I have replaced so many panels and transistors its crazy!

If you are drawing massive amperage through the system with maybe a bad battery, or even a bad Motor, The field windings of the motor or the armature, commutator all of these are potential issues. 012 being PS pump motor code first are the brushes welded to the commutator?

You have a massive draw or short in the system the power cables running through the frame and under the battery I would check first.

Diagnostic mode: Hold 1 & 4 turn key on, push 3
To run self diagnostic
Hold 1 & 4 turn key on, Put in Forward, and push 1

Programming: Use on board system with dash display
Hold 1 & 3 and turn key on
============================================

Also don't forget the normally closed side of the Directional Contactors, the 1A , and flyback contactor.

One other thing is the main speed board in the back that covers the contactors, if that touches one of the contactor bars because someone pushed on the back door or whatever it will blow the board and the transistors immediately.

Yup I have the manual. Thanks

Just check anything you can check, sometimes power goes throw all different parts of controller.
Do you have a manual?

You mean the IGBT modules? Those are for the power steering aren't they?

You mean the IGBT modules? Those are for the power steering aren't they?

You better check all RGBT modules and transistors

I just thought of something. I bet that hole entire panel is mounted on a rubber sheet. I wonder if its shorted to the frame

No, I wish it was that easy. 400plus amp traction transistor keeps blowing. A card (I dont think) cant do that. Thanks for responding

Possible fault on logic card?