Oil Gauge

Robert F. · Jun 17, 2012

2003 GMC Sierra 1500 5.3 engine, 130000 miles. Meticulously cared for. Oil and filter changes every 3000 miles. Does not use oil. While driving, warning chimes sounded and "LOW OIL PRESSURE" indicated on the Driver Information Center. I stopped, checked oil which was at normal level. Cautiously continued on my way, listening intently to the engine sounds which remained perfectly normal. Oil pressure gauge indicator is at the top of the scale, 80 lbs. With engine stopped and not having run for 24 hours, I get the same oil pressure reading if I turn the key on but engine not running. Does this sound like a bad sending unit? If so, where is it on a 2003 GMC 5.3 engine?
Thanks

Diamondpilot · Jun 17, 2012

I think you are looking in the right area. The other thought is the GM truck dash clusters of that era are junk. Look on the net. There are 100's of places repairing them. It could be a bad dash cluster (showing high pressure and setting off the chime/DIC notice)

Chris

frischtr · Jun 17, 2012

I'm not sure if the GM trucks are like this, but many vehicles' oil pressure gauge is really a dummy gauge with a display signal sent by the ECM based on a combination of engine RPM and coolant temp. If this is the way that gauge works, there could actually be a problem with the oil pump and the gauge wouldn't show it. Your warning sign came in the form of the 'low oil pressure' indicator. I'm sure someone with more knowledge on these engines can chime in.