2005 Chevy Silverado 1500 5.3l

[Justin Posey]

So I’ve had my Silverado for about 4 maybe 5 years now and when I first got the truck, it only had about 135k on it. Today it now has 190k. Still runs smooth like never before. The only problems I am having with it is for about a year now my truck seems to have a flicking with every electrical component inside and outside the truck (only when cranked). The alternator has been replaced, battery as well. The battery gauge on the cluster gauges (when the truck is cranked) will move up and down between 12-16, according to the gauge and because of that, the “Service Charging System” appears in the Notification Center. When the truck is off and the key is turned but not cranked, nothing flickers. The engine light is on and I attempted to plug in my OBDll reader into the data link port to see what it says and there is no response, my OBDll reader has a built in battery and claims that it’s not connected to the truck. All wiring looks great, no modifications were ever done to cause any of this to occur. Last but least is that when I start the truck, it tends to have a pretty rough idle between 600-700 RPM and then after a while of it warming up (still idling) it will start to have a loud but not heaving tick/knock in the engine. After the engine has warmed up 100% and I start driving, the knock/ticking starts fading away And then eventually (with continued driving) the knock/tick is gone, then the truck runs 100% smooth acting like nothing is wrong with it (other than the flickering). One thing I have been paying attention to is that the oil gauge in the cluster gauges, when idling (already warmed up) the oil pressure is below 40, as I rev the engine to 1000RPM, it starts to increase, the higher the RPMs, the more it increases, because the oil pressure is so low when idling, I think that could indicate that the lifters and pushrods may not be getting enough oil because of that low pressure. I just need advice here haha and I know it’s a lot of stuff going on with this truck but I know it can’t be too serious if things are still after a year resolving themselves. I feel like if I were to fix the electrical issue with the truck, I really think it may fix my oil pressure and maybe other things as well. 

[txab]

For OBDII link issues, first check the cigarette lighter fuse. OBDII port is on that circuit.

 

For electrical issues start by checking/cleaning body grounds. Check battery cables.... they can and do go bad occasionlly

[dsr611]

Flickering is probably a grounding issue.  Locate the gounds and clean.  Replace negative battery cable (corrosion is possibly under the insulation).

 

No response from the OBD reader--check cigarette lighter fuse.  Cigarette lighter fuse protects lighter, cruise control, and OBD port.

 

Oil pressure issue--get a manual gauge and double check the pressure.  With GM trucks and SUVs of that generation (01-06), it's hard to rely on the instrument panel gauges due to the stepper motors used in the gauges.  They are notorious for going bad and giving false readings.  If pressure is actually low, might want to check pickup tube o-ring

[Justin Posey]

Alright that helps loads, I’ll look into the body grounds, as far as the cig lighter and cruse control goes, they both work, just the OBDll port not working! Checked every fuse from under hood and driver side fuse box and nothing is blown

[Doug_Scott]

Did you check by just looking at the fuse, or did you use a test light touching the legs of the fuse?  You can test for power on the top of the fuses, they all have access to the legs from the top of the fuse.

 

40psi is plenty of oil pressure.  On vehicles with idiot lights, the light will come on when it drops below 10psi.  Back in the old days(50 years ago) the oil pressure lights came on below 7psi.  Years ago Fords had their oil and temp gauges with the acceptable range marked out and the word Normal under that range.