This 2002 Buick Rendezvous came in with the complaint that it would not run at times. Started out just a problem sometimes but now it is most of the time. I checked for codes and the only one present was for a fuel level sensor. I checked fuel pressure and spark and they were both present. After doing an injector balance test (passed) with my Tech 2 scan tool the engine fired and ran for a few seconds. So the base problem was no injector pulse while cranking the engine. I made sure there was no anti theft codes current and there were not.
After looking over service information I decided to look at the cam (CMP) and crank (CKP)”A” sensors. In checking for power and ground at the CMP sensor harness connector I found that there was no 12 volt supply on the red/white wire. During my research I read that the CMP and the CKP “A” sensor shared a PCM internal driver although they are connected to two separate external wires. I disconnected the harness connector for the CKP “A” sensor and power came back to the CMP sensor harness. I was about to condemn the CKP “A” sensor as shorted when I noticed a problem with the wiring just behind the a/c compressor.
I disconnected the harness that went to the compressor and pulled the whole harness down for a good inspection. There were multiple raw wires and it appeared that some had been touching each other. The light green wire is the 12 volt power supply from the PCM to the CKP “A” sensor. By the way this sensor is also known as a 24X sensor.
I separated the wires and and replaced the damaged areas one at a time. I made sure to stagger the joints so the the harness would go back together neatly.
I installed some split loom over the wiring to add some protection to the harness.
A pretty neat job even if I do say so myself.
Now I have a nominal 12 volts back at the red/white wire at the CMP sensor. I also had the same voltage at the light green wire at the 24X sensor.
I reconnected all of the wiring and the engine started right up. The wiring had been damaged by years of sloppy oil changes. The oil collected in the harness right at a turn and stayed there. As a result the insulation merely dissolved, leaving the wires exposed to each other.