This may be a bit technical, but here is the explanation I found for your codes:
P1505 = Idle Charge Actuator signal low of coil #1
P1507 = Idle Charge Actuator signal low of coil #2
They both pertain to the "Idle Charge Actuator," or what is sometimes called the Idle Air Control (IAC). Here's what it means:
The IAC is a modulating valve, or a valve that can be positioned at any point in its operating range. In other words, it can be open or closed at any point, like when you open a water valve on your kitchen sink to change (modulate) the flow to the rate you want. (This is as opposed to a two-position valve, which is completely closed or open with nothing in between.) The engine control computer controls the valve position to allow as much air past the throttle valve as is needed to control idle speed.
There are two electrical coils in the valve, the opening coil and the closing coil. The computer constantly sends a controlling signal to one or the other to position the valve. The IAC has a connector with three pins in it: The #2 center pin supplies +12 volts from the battery, when the ignition switch is on, to a common connection of BOTH coils. The #1 and #3 pins are the other sides of EITHER coil and are switched by the computer to ground as needed to position the valve. If a volt meter's probes are put between pin #2 of the connector from the car's wiring harness
and any ground, it should show +12 volts being supplied with the key on. That tells you that there is power being supplied. If a meter is probed between #2 and either #1 or #3 of the connector on the IAC valve
, it should show the resistance of the coils in the valve, which should be around 15 ohms to 18 ohms. This will show if the coils in the valve are good or bad. If you know anyone who can use a multimeter, he (or she!) should be able to determine all this.
I know this is a bit technical, but my background is in control systems with several decades' worth of shadetree mechanic work. Not to mention twenty four years in aircraft avionics systems in the US Air Force and Air National Guard. Consequently I am apt to lapse into Geek Speak at times.
Check back if I can confuse, uhhh help, you any more.