Coil Negative getting power and not starting - Slant six
It is normal to show "a little" power at the coil neg, did you measure voltage, or just put "a light" on it? Light is dim? normal
Is the ECU grounded FOR CERTAIN?
Full battery voltage on both sides of the ballast either indicates no current through the coil or a wiring problem in the ECU harness
Trace the neg. coil wire back to the ECU and make sure it's continuous
Make sure the ECU is grounded.
I assume? later model ECU with 2 pin resistor? Is it possible you have an older 5 pin box? You cannot tell "by looking," some replacement 4 pin boxes have 5 pins. You must check continuity from the "5th pin" to the other pins to see if there is any connection
Simplified "4 pin" ECU wiring:
It is normal to show "a little" power at the coil neg, did you measure voltage, or just put "a light" on it? Light is dim? normal
Is the ECU grounded FOR CERTAIN?
Full battery voltage on both sides of the ballast either indicates no current through the coil or a wiring problem in the ECU harness
Trace the neg. coil wire back to the ECU and make sure it's continuous
Make sure the ECU is grounded.
I assume? later model ECU with 2 pin resistor? Is it possible you have an older 5 pin box? You cannot tell "by looking," some replacement 4 pin boxes have 5 pins. You must check continuity from the "5th pin" to the other pins to see if there is any connection
Simplified "4 pin" ECU wiring: