terravast4

iTrader: (25)

My friend has like a 2002 silverado with a 4.8 , today his wife id driving the truck and the check engine light flashes for a while then stops. later on flashes for a while and stops (only flashing under load) I told him I thought it was mis-firing. later in the day his wife calls and says the truck is running bad and hardly has any power and the light is continoually flashing. I told him I thought it was in limp mode and I loaned him my scanner to pull some codes. I plugged it in my truck to show him how to use it properly. he calls me from his house later and says the scanner wont turn on. when he turns the key for acc for the scanner nothing happens. he couldn't even start the truck. When he unplugged the scanner the truck would start. with the scanner unplugged with the key in acc the door chime would sound but when he plugged in the scanner the chime would stop and dash lights would turn off. Is there some sort of protection in limp mode thet will not let you read or clear codes. Thanks in advance for your help. Oh one more piece of inportant info a month or so ago he was pulling codes for o2 sensors but not sure what the code was do you think he has a bad cat that is causing a restriction? any help would be appreciated.

GMCtrk

iTrader: (27)

Check the plugs and wires

v8

iTrader: (10)

clogged injectors. or fuel pressure regulator.

budhayes3

iTrader: (19)

Blinking MIL=misfire, could be alot of things. Yes, clogged cats will cause no power and misfires, but it could also be a spark plug, wire, injector, coil, etc...even a failing fuel pump.

The scanner issue is wierd, maybe a compatability issue or even a blown fuse somewhere. Oh yea, the key needs to be in the ON position to get the codes BTW, but that doesn't explain why the truck wouldn't start with the scanner hooked up. What kind of scan tool is it? Is the cable to the scanner good and not possibly shorted somewhere?

terravast4

iTrader: (25)

It is an actron scanner and it is not a cheap one, I paid about $200 for it and I use it all the time with all the problems I have had lately and It has always worked flawlessly. I was not there while he was using it so i tried my best to coach him and troubleshoot over the phone but I thought it was odd the truck would not start with it plugged in and I could hear it trying to start over the phone then I told him to unplug the scanner and the truck started right up. normally re scanner will turn on as soon as you plug it in and turn the key to accessories but this never happened and to boot the dash went dark....unplug the scanner and the dash lights up.????????????????????

TXsilverado

iTrader: (19)

check plugs, wires, coil packs, injectors, pump, regulator...

how many miles are on the truck? has the fuel filter ever been replaced? it will most likely be plugs, wires, or clogged injectors.