Thank you sir for replying and bearing with me. And yes, there is a certain amount of guessing on my part, but only because I have asked 3 different "experts" so far about my problem and have gotten 3 different answers. This is a 2000 Oldsmobile Alero with a 2.4 L engine. I'm sorry but I thought I had said that before. Some say pin #85 is ground and pin #86 is hot coming out of the PCM. Others say the opposite. Some say pin #87 is always hot with the key in the "on" position. You seem to be telling me that pin #87 is getting it's hot from the oil pressure sending unit (which would only be hot once the engine achieves oil pressure, ie; during cranking or running) That makes more sense to me at least over the others. Also, some say pin # 30 is the grey wire leading straight to the fuel pump. You seem to be saying that it powers the injectors. Unless, you meant that it powers both. If I understand you correctly, you seem to be indicating that 86 is always ground to the coil inside the relay and 85 supplies hot from the PCM to the coil for 2 seconds which closes the contacts between 87 and 30 and primes the fuel pump. Where I'm getting confused is this: With the key in the "on" position (and not cranking or running) then how is 87 getting power from the oil sending unit to power the fuel pump on for 2 seconds? Are you saying that THAT power comes from the PCM itself via pin 85 for 2 seconds and then once cranking or running the coil opens back up and then the power comes from the oil sending unit? ( In other words the little coil inside the relay is only energized for 2 seconds to prime the pump and then the rest of the time it's open as long as the engine is running and has oil pressure?) But wait, what would be holding the contact between 87 and 30 closed then? I thought the little coil did that. Now, I've confused myself even more. I thought I was on the right track for a minute at least. Could you do me a favor and run it down for me step by step as for example:
(1) Turn key on and PCM supplies power to coil via pin #?
(2) coil closes contact between pins 87 and 30
And etc; etc. I would greatly appreciate it so I can get a 100% clear understanding of how it works exactly and then I can do further testing with my multimeter and know EXACTLY what I'm testing and how and why and then I can save money by not buying parts I don't need. Thank you so much in advance!
Tuesday, August 27th, 2013 AT 12:42 AM