Jaguar Repair: 1985 jag wont start, coolant temp, diesel battery

Question
QUESTION: Howard my 85 jaguar shut off while driving  the fuel pump is good the injector does not open i have I've one side of the the wire  there no negative signal from the ECU  how can i check the ECU

ANSWER: Hi Steve,
The ECU gets it's signal to ground injectors from the ignition system so the first step is to check the single bullet connector on the top of the intake manifold about in line with the injection system coolant temp sensor. (second one from the rear) If you know that you have fuel pressure and that you have power to the other wire in the injector plug then you have power to the ECU because it is the same power supply. (Other than a bad connection at the plug connectors at the back of the intake manifold or at the plug behind the battery that goes through the firewall.)
Also you need to be sure you have a deep charged or diesel battery as that is a unique symptom of the Series III Jag when a standard battery is used. This is simple to test. Even with a well charged battery in the car connect a second well charged battery as a jumper battery like you were jump starting a car with a dead battery and if it starts and runs you need a new "Deep Charged" battery.
If you need a wiring diagram to test further and don't have one, let me know and I will load one up on my web site for you to copy.
Howard


---------- FOLLOW-UP ----------

QUESTION: Howard have you ever came across a bad ECU here is what i done so far {1} ck the wire from the negative side of the coil with a continently tester  back ck to ECU {2}ck ck every negative wire from the injector plug bauk to the ECU all good this leave me a the ECU unit  fuel pressure is 40 lbs

Answer
Steve, I'm sure an ECU can fail but I have not run into one, but have heard of a failure when a battery was installed backwards. 40 PSI is ok if the engine was not running as that is the "No vacuum" reading. with vacuum it should read about 32 PSI.
Do you have a pulsing signal to the ECU from the ignition? and do you have power to the ECU? And did you have power to the injector resistor pack?
Howard