Quote:
Originally Posted by 67farmtruck
Yes - I have 12V on the red wire at the ignition switch
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Are you measuring that with the key on or off?
The reason I ask is because there could be a poor connection (excessive resistance) somewhere in that red wire between the battery and the ignition switch and it will only show up as a voltage drop when under load.
For example, with the key off and no current flowing through the wire, there won't be any voltage drop so you would read 12V on your meter. But when you turn the key to the on (or start) position, the ignition (and starter solenoid) draw current. And if that current is trying to flow through a poor connection it will result in an excessive voltage drop.
So if you were measuring 12V on the red wire with the key off, try measuring it again with the key in the on or start position. If the voltage on the red wire drops way down, follow that red wire back to the battery, checking for bad connections along the way.