Tips
Technical Information and Restoration Parts for the 928

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Wiring Tips

Below is a list of things that I have noticed while working on the wiring.  They are in no particular order, but if you are having strange wiring issues it is worth looking these over.

bulletWiring Harness - The wiring harnesses are covered with a heavy plastic cover and held in place with metal tabs welded in strategic places.  The metal tabs have sharp edges that can over time wear through the plastic cover and cause shorts.  The most vulnerable area is the cable that goes to the warning system control unit under the dead pedal.  The tab at the top inside of the firewall where the cable makes a sharp bent has a tendency to wear and cause phantom warnings.
bulletDoor Locks -  The fuses for the electric door locks are not located on the fuse panel.  They are located on the top of the panel in two black fuse holders that are clipped to the back of the panel.  If one of these fuses blows then the door locks will not synchronize.
bulletAlarm System - The alarm system is activated and de-activated by grounding the control wires.  These wires run to each door lock and the hatch lock.  They are installed on the older cars in a separate harness.  Water and wear can cause these wires to contact ground randomly activating the alarm system.  Since the alarm system when activated disables the ignition false alarm activations can cause the car to get stranded.  The most common point for shorts is the area around the rear hatch.
bulletBlinkers - While installing the pod I accidentally shorted the contacts on the hazard warning switch on the pod.  After checking the all  of the fuses on the main panel I finally tracked the problem to the switch itself.  The fuse protection to the hazard warning and directional lights is located in the switch.
bulletBattery Draw Down - It is not uncommon for the battery to be drained over time if the car sits.  The draw normally should be very low and not affect the charge, but various accessories can fail and add to the load.  The one I tracked down was the rear window defroster relay.  It was sticking on and draining the battery. 
 

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