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Re: Dead #3 cylinder Posted by Justin VanAbrahams [Email] ![]() ![]() In Reply to: Dead #3 cylinder, Bill Montgomery, Fri, 20 Dec 2002 17:06:52 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Dana is right about the wiring. LH is a batch-fired system. When you turn the key on, power is supplied to all the injectors. During injection pulses, the ECU grounds the other terminal on the injector causing them to open all at once. So, it's normal to have +12v on both terminals with the key on but the engine not running, as the ground signal from the ECU will be missing.
I'm no electrical engineer, but I think you could safely use a test LED (don't use a lamp!) plugged into the #3 injector harness and try running the engine. If the LED isn't flashing with injectors pulses, you've got bad wiring or a bad ECU or both. You could use the wiring diagrams in Bentley to trace back the #3 ground line to the ECU harness and check for continuity and integrity.
To answer your final question, there is no danger in unplugging the ECU. Just be sure you give the system a few minutes after turning it off before unplugging, as the fuel/system relays can retain a charge for a short time. Of course, you can unplug them first and save the time. Just handle the unit with care. That said, most of the tests in the Bentley assume the ECU is plugged in during the tests. In that case, follow the instructions in there for removing the boot from the back of the wiring connector and test from the rear.
-Justin
posted by 64.166.4...
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