I just purchased a 2000 Silverado Ext Cab with 240k miles on it. Truck runs well but has several codes.

I currently have the SERVICE ENGINE SOON light on and can't seem to make it go away. I was told to disconnect battery, pull ECM fuse. No luck.

The stored codes are

P0300
P0161
P0332
P0141

The previous owner replaced one of the coil packs about a month before I bought it.

So far I've done basic maintenace on the truck.

Oil and filter change
flushed radiator
changed thermostat
changed coolant temp sensor

My understanding is that these trucks have both a Check Engine Light (CEL) AND a Service Engine Soon (SES) light. Is this correct?

Also have the service 4WD light on. When this is going on the 4wd system will not work. A reach into the dash and pressure on the wiring harness into the back of the 4wd switch seems to fix this problem temporarily.

Also having an intermittent problem with the security system. At times it will simply not turn on. After about a dozen or so key cycles the truck starts up and runs.

And my OBDII Bluetooth scanner won't connect with the computer... What gives?

Please help me sort through these problems.

Keith

 

Sounds to me like something ate into the wiring harness...

Or bad connections, or the brain (computer) is dying.