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Discussion Starter · #1 ·
I just got my oil changed in my 2002 4.2 4x4 Chevy Trailblazer. 3 days later - my oil pressure low indicator start flashing and the gauge would drop to zero then the display would flash stop engine. I immediately pulled over and turned the truck off. Checked my oil level. Then I realized I needed to wait until it cooled. Once it cooled the oil level still showed that it was fine on the stick. I started the truck back up and began to back out. In reverse the car seemed to stop on its own without me applying the brake after a few feet. I put it back in drive and it seemed to drag. I called and then took it back to the folks that did my oil change. One of the service people took the car to check it out. He came back and said, your 4x4 was on. I contested since I am the only one who drives and I don't use the 4x4 at all. But I drove it and none of the issues occurred.....until yesterday. This time, I no that the 4x4 isn't on and I am having the same issues. Is there anyone who knows what might be going on. I know that there is a chance that I may have to get the oil pump replace (God no!) but I am really hoping that it is something less complex and inexpensive than that. Could there have been something that the service people didn't put on right that may be causing the malfunction. I want to go in and have some ideas if that is a possibility. Sorry for the long thread. Wanted to make sure I gave all of the information for a clear answer. Thanks Trailvoy!
 

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2002 chevy trailblazer_lt_ext
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Defective or improperly installed oil filter, defective oil pressure switch, damaged wiring between the oil pressure switch and the PCM, and even a failing ignition switch could cause this problem.

I wouldn't go straight to blaming the oil pump just yet. Besides I have never heard anyone report losing an oil pump on the I-6.
 

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2002 gmc envoy_slt
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I had an 89 New Yorker that would suddenly drop oil pressure and turn on the 'Low Oil Pressure' and a message to turn off the motor. Ended up being the oil pressure sending unit was bad and needed replacement. Now we don't have a true oil pressure sending unit, our trucks use a simple double pressure switch and the PCM/BCM calculates what it thinks is the actual pressure based upon the rpm where the switch turned off (read pressure over its threshold) during startup.

Now, you don't usually magically get oil pressure back, you either have a problem or you don't. My guess would be as mentioned above, a bad switch or wiring issue. I'd personally replace the switch and while I had the switch off, connect a manual oil pressure gauge for a few minutes and check the pressure at idle to verify proper operation.

As for the stopping/dragging and the 4x4 supposedly being on.....don't completley dismiss the 4x4 being on. The early selector switches had problems and they redesigned them. With the switch in the 2HI position, I observed mine momentarily jumping into either A4WD and 4HI on several occasions. (Usually had I made a turn or attempted to turn into a parking space, when the front wheels would crow-hop and make it impossible to finish the turn). Of course unless you looked at the lights over the switch at the right time, you'd never have known it had done so. Trip to the dealer for a new switch fixed the issue. (Keep an eye on the lights, should the that problem re-occur).
 

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Discussion Starter · #4 · (Edited)
LOL at neelskit. I appreciate the oil pump comment. To both of you neelskit and ylab, I certainly appreciate your input on this and it allows me to go to these folks and tell them what they need to check out before they hurriedly tell me that its nothing that they did. My best guess is what neelskit said in reference to the oil filter not being properly installed. Anyone can make a mistake and thinking back, they did the work a lot faster than they usually do and they had a lot of customers on this particular day. Thanks and I will let you know if I get this resolved. Although I am not fully up on the mechanics of the matter, it just makes since because the failure is not consistent - almost like its partly connected.

The advice here is always great and since I plan on keeping my well used Trailblazer for a while I think I am going to up my subscription!:thx
 
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