Parking (hand) brake

The parking brake (also known as the 'emergency brake', 'e-brake' or 'hand brake') on a DeLorean is a mechanical system which is operated by the lever which pulls a left and right cable. The two cables are connected to mechanical hand brake calipers, which are attached to the rear brake calipers. These small calipers are completely separate from the larger hydraulic service brakes, and have their own parking brake pads PN 109037.  
 Common Issues/Diagnostics:
1 - One or both of the cables may become detached from the mechanism in the handle.
2 - A cable or cables may become out of adjustment due to wear (or loss) of the brake pads or due to resurfacing ("cutting"") the brake rotors. There is an automatic adjustment mechanism, but it very commonly fails and stops automatically adjusting. When that happens it's best just to manually adjust the calipers from time to time. The adjusting mechanism is somewhat fragile and rust-prone, and the pads don't wear very much over time.  
3 -  Occasionally we will see the retraction plate that holds the pads apart break - this and the tab washer are easily replaced. 
 A suggested method for diagnosing the problem is to jack up the rear of the car and support it with jack stands. Remove the rear wheels and inspect the brake pads on the parking brake calipers.  Have an assistant sit in the car and operate the handbrake while verifying that there is movement on the lever on the caliper where the cables attach. Check both sides.  
There are inner and outer pads, and occasionally one of the pads will fall off. When that happens, that side will stop working.
If there is movement on both sides, and the pads are intact and worn evenly,  proceed to adjust the handbrakes. 
If the cables don't move, and the handle offers resistance when pulling, one or both (usually the right side) cables are probably rusted in internally and need to be replaced. 
If the cables don't move and the handle feels "disconnected", it is most likely that one or both of the cables have come off the relay bar at the handle itself. To check this, slide off the rubber handle cover from the hand brake, then remove the carpet trim cover. The trim cover may be held into place with two "buttons" hidden by the driver's seat - seat removal may be required.  Look to the rear of the hand brake mechanism with a flash light through the slit in the mechanism. It is possible to see the ends of the cable which go through the relay bar, basically a floating bar with a pivot in the middle and a notch on either side to which the end of the cables are attached.  If you shine a light through there and you see that one or both of them are disconnected, the way they should be attached is obvious, as is how you need to re-attach them. It can be difficult to pull the cables back in to place, and we find that a zip-tie around both cables close to the relay bar will help prevent this from happening again.
 After reattaching the cables, pull up on the handle and inspect the action of the relay bar. If the pull is not equal, i.e. the bar is tilting one way or the other, adjust the brake calipers to make the action even and activate both brakes simultaneously. 
There are two adjustments at the caliper end of the cables. The ferrule adjustment can be used to "balance" the relay bar. 
The caliper screw adjustment is more of a "fine tuning" mechanism to balance the brake action between the two sides of the car.  On each of the parking brake calipers you will see that there is a very thin cotter pin that goes through a screw which is holding it in place. Remove the cotter pin, turn the screw in a clockwise direction (to tighten), while trying to turn the brake rotor. Once the parking brake pads grab on the rotor to the point it will not move, turn the screw counter-clockwise until the rotor does turn. Continue counter-clockwise enough to reinstall the cotter pin. 
Written by Warren Wallingford with edits by James Espey, DeLorean Motor Company (Texas)
Revised DAS 8/4/2016 major rewrite