Code Reader Power

[JackRH]

Stopped by Auto Zone to have a check engin light cleared but their reader would not read. They said a fuse was blown that powers the reader.
I've checked every fuse I can find but can't find a blown fuse. Anyone know where this fuse might be located on a 2002 duramax?

Used another reader that had it's own power but it would not read either. It kept saying I needed to turn on the key.

Thanks for any help.
Jack

[DmaxMaverick]

Many reader/vehicle combinations will power up, but have no PCM access without the key on. 2002 GM trucks are one of them.

The cigar lighter circuit/fuse powers the scanner/tool plugged into the diagnostic port. The circuit should be powered, key on or off. If you have a device plugged into the lighter or power outlet at the time the scanner boots into the system, the device power draw may prevent it (this is why they all recommend powering everything off). You can also use any 12V source to power the scanner devices (doesn't have to be from the port).

[JackRH]

Thanks don't remember having anything plugged into the lighter socket unless it was an unused charger cord for my cell phone.

I did check that fuse and it tested fine.

Any other ideas?

Thanks again
Jack

[DmaxMaverick]

While it shouldn't cause a serious immediate power draw, device charge adapters can consume considerable power when plugged in, even if the device isn't connected. If your electrical system is on the edge of failure (like bad batteries), it could, theoretically, drop the line voltage enough for a sensitive scanner to fail at boot.

Other than that......

Do all of your other electrical accessories/systems work? Check them all.

Check the underhood power distribution buss (fuse box) for a related fuse, circuit breaker, or relay.

Check the pins in the port and make sure they aren't pushed out, bent, or damaged.

Probe the port (with a VOM or test light) for Batt+ voltage (key OFF). Also verify the system ground pin.

[Kennedy]

Definitely check all power and lighter ports. Rememebr they are on different circuits.

To save a trip to auto zone or a dealer:

http://www.thedieselpage.com/reviews/quicklynks.htm

Having the ability to DIY code read can be priceless especially when on the road...