Not Getting 12 Volts at Coil
Instructions given to me are in lower case letters. MY ANSWERS ARE ALL UPPER CASE.
1. With the wiring to the + coil terminal disconnected, the wire should register 12 volts when ignition is on and also when cranking. Test for this with a test light and voltmeter. (When using a test light, the light may be dim when ignition is on but bright when cranking. This is normal because voltage is cut in half by the ballast resistor when ignition is in RUN, but not when cranking. Either way, you should see 12v whenever the coil wire is not connected to anything but a meter.)
10.7 VOLTS WITH IGNITION IN RUN. 9.6 VOLTS WITH IGNITION IN START.
2. Test for good coil signal by connecting a test light between the battery positive terminal and the coil negative terminal, and then cranking the engine. A bright flashing light means the signal from the ECU is GOOD. No flash means the ECU may not be grounded properly or it is not getting switching signal from the distributor.
MY TEST LIGHT CLAMPED ON THE (-) COIL TERMINAL AND THE TEST LIGHT PROBE ON THE + BATTERY TERMINAL. LIGHT WAS STEADY ON. WHEN CRANKING, IT DID NOT FLASH.
3. All these problems can be caused by bad connections between components you have replaced or bad grounds. If your engine starts fine when supplying 12v directly to the coil positive terminal from the positive terminal (hotwiring), then you must check for bad wiring between the battery and coil via the ballast resistor wiring, ignition switch and starter wiring.
I HAVE TRIED A JUMPER WIRE FROM THE + BATTERY POST TO THE + COIL POST MANY TIMES. THE STARTER WORKS FINE, BUT THE ENGINE DID NOT RUN ON ANY OF THESE ATTEMPTS. THE BALLAST RESISTOR IS NEW.
4. Using test light connected to body ground, probe coil POSITIVE WIRE with coil disconnected from it. Bright in Crank, dim in RUN.
WITH MY TEST LIGHT CLIPPED TO THE BODY GROUND, PROBE TAPED TO THE + COIL WIRE, NO CHANGE IN BRIGHTNESS FROM RUN TO START.
5. Now, hook the coil back up. At the wiring harness connector that plugs into the ECU (ECU unplugged):
Terminal 1 Bright in RUN, dim in START.
NO LIGHT IN RUN. LIGHT IN START.
Terminal 2 Dim in START, even dimmer in RUN. No light at all means open coil circuit.
NO LIGHT EITHER WAY. I HAVE NO IDEA WHAT OPEN COIL MEANS OR HOW TO CORRECT THIS.
Terminal 3 Dim in RUN, even dimmer in CRANK.
NO LIGHT IN RUN. LIGHT IN START.
6. If these tests are good, the ballast resistor wiring and the ignition switch are OK.
I DONT KNOW WHAT MY RESULTS TELL ME. MY BALLAST RESISTOR IS NEW. I KNOW THAT THE TESTING ON TERMINALS 1, 2, AND 3 WERE NOT WHAT THEY SHOULD HAVE BEEN. WHAT DO I DO NEXT?
7. Terminals 4 and 5 probe with ohmmeter for resistance through pickup coil and back. Should be between 150-900 ohms.
MULTIMETER SET AT 2000 OHMS 449 READING.
8. If all this checks okay, inspect for correct pickup gap inside the distributor using a plastic or brass feeler gauge. Spec gap is .008 and no more than .010 with vacuum applied to advance canister.
I DID THIS SOME TIME BACK. IT WAS .008.
9. Check the resistance between pin 5 on the ECU and body ground. It has to be less than .5 ohms. If its more, clean and remount the ECU. If still shows resistance then ECU is bad.
I PUT THE NEGATIVE PROBE OF THE OHMMETER ON THE BODY GROUND AND SET THE OHMMETER TO 20 OHMS, 200 OHMS, AND 2000 OHMS AND TOUCHED THE POSITIVE PROBE TO THE #5 PIN IN THE WIRING HARNESS. THE 1 DID NOT MOVE. I THINK I DID THIS TEST WRONG, SO I TOUCHED THE POSITIVE PROBE TO THE #5 PIN ON THE ECU UNIT:
20 OHMS - 1 MOVED TO 2.20. 200 OHMS - 1 MOVED TO 23.9. 2000 OHMS 1 BOUNCED AROUND 560-580.
10. Lastly, check resistance between pin 5 on the ECU and the battery negative terminal. If resistance is found, then repair the battery ground.
I PUT THE NEGATIVE PROBE OF THE OHMMETER ON THE BATTERY NEGATIVE TERMINAL AND SET THE OHMMETER TO 20 OHMS, 200 OHMS, AND 2000 OHMS AND TOUCHED THE POSITIVE PROBE TO THE #5 PIN IN THE WIRING HARNESS. THE 1 DID NOT MOVE. I THINK I DID THIS TEST WRONG, SO I TOUCHED THE POSITIVE PROBE TO THE #5 PIN ON THE ECU UNIT:
20 OHMS - 1 MOVED TO 2.25. 200 OHMS - 1 MOVED TO 24.5. 2000 OHMS 1 BOUNCED AROUND 569-590.
DO I HAVE RESISTANCE? IF SO HOW DO I REPAIR IT. MY CAR AND ENGINE COMPARTMENT HAVE BEEN PROFESSIONALLY PAINTED. DO I NEED TO SCUFF UP CERTAIN AREAS SUCH AS THE BATTERY GROUND OR THE ECU MOUNTING AREA? WHAT NEXT?
