lasercowboy;98007 wrote.... With the ECU unplugged, and monitoring the voltage on the red wire heading into the fuel pump relay, I removed in turn each connection into the EZK box. The only one that did anything was removing the brown earth wire on pin 20, which caused the voltage to rise from 2.2V to 4V. ...
Connecting the EZK is loading up the circuit, so you're seeing a voltage drop at pin 5. Disconnecting pin 20 of the EZK is disconnecting the ground for the whole box, and doing that isn't advisable. However, by (partially) unloading the EZK from circuit, you're seeing there's a problem on the +12V battery [30] rail. It should be 12V at pin 5, all day every day - regardless of if the EZK is plugged in or not, or if pin 20 is grounded or not.
Here is the EZK116 diagram. <p>
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Below are the pinouts for the EZK116 and the signals you should see on them.
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The description of testing you've done so far indicates to me that there's a wiring problem on the red wire/battery/[30] bus - either a high resistance connection, or a short circuit to ground, somewhere. To find this problem, you need to trace that red wire back to the battery, or the last place you're seeing steady 12V. Then move your way forward, testing at each point, until the volts go AWOL.
