THe door locks on an SD are operated by a pump in the trunk, the shutoff is hooked into the engine vac system. Looks like it is down to good ol' vacuum troubleshooting for the OP. There are some great vacuum guides in the DIY resources on this site - I highly recommend taking a look at them.

As far as the HHO, I wonder what long term effects it will have on the engine? I know that starting fluid can seriously damage a diesel and considering the explosive nature of hydrogen, you'd be changing the combustibility characteristics (heat, pressure, etc.). I wonder if it is similar to using ether?

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth