You can't check three-wire sensors with resistance measurements because there's a bunch of circuitry inside them. The 4.5 volts you're finding on the signal wires proves that circuit is okay. It is sent by the Engine Computer for self-testing when the 5.0 volt supply is missing. You are on the right track with the missing supply voltage on the orange wires. I can't remember if that is supposed to be 5.0 volts or 8.0 volts, but it's irrelevant at this time. That voltage comes from the Engine Computer. That wire has to be grounded or open. If it's grounded, the computer will shut it down to protect itself, and if you find the short, the supply won't come back until you turn the ignition switch off and back on.
Start by unplugging both sensors, then see if the supply voltage shows up on the orange wire. If it does, one of those two sensors is shorted. If it doesn't, follow that wire back to see if there's a break in it.
Aug 8, 2016 at 9:00 AM
