I used a noid light to see if my rear injector is energizing. With the P0264 code it won't flash. If I erase the code, I get flashing for a little while and then it doesn't. May be a few minutes to several minutes. With the injector unplugged and the noid test installed in the socket, I tested for power ar the onnector power feed side. I get 12 Volts. Just past the connector bulb I get 12 volts. Good so far. What I need to see! Back probing the ECM plug, I get 12 Volts. If I got 0 volts, there would be a short at that circuit to the ECM. That leaves the internal ground switch in the ECM. I know the ECM is good, because it will run and flash for a while.

One of the Inputs is not allowing the internal injector switch to switch to ground so that the ECM will not be damaged. Inputs could be IAC, TPS, MAP, etc. I have had problems with IAC to run high RPM and then settle to 1000 RPM. IAC is in the fuel injector circuit.

Anyone know which sensor(s) could be causing the injector circuit internal in the ECM to cause the switch not to ground?