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OBDII fault codes


70camaro
01-03-2004, 06:26 PM
I have a 97 gmc 1/2 ton 4x4 with 100k miles. A few days ago my SES light came on. I have NOT noticed any problems. I am fairly capable under the hood, but have never had to work on my newer vehicles. So, I bought a scan tool to retrieve the dtc's. I got P1406 and P1300. The code definitions are very general, and I dont know where to start. Is there a manual or book or internet resource that will explain these IN DETAIL??? I dont want to just start replacing parts, I already spent 300+ for the scanner!!

GMMerlin
01-04-2004, 07:37 AM
The 1406 code is for the EGR performance...there is a bulletin #76-64-04 that covers a calibration update for that.
The 1300 code...there are some 1300 series codes..it all depends on the last 2 digits as to what is at fault...there is no 1300 code.

70camaro
01-04-2004, 08:05 AM
The scanner says "P1300 Ignition Control Module (Igniter) Circuit" No #'s after, just straight P1300.
I'm guessing the update needs to be performed by the dealer? Do you know of a resource that will give detailed info about the dtc's?

70camaro
01-05-2004, 05:03 PM
I ran a few checks on the EGR > checked for 5volts from PCM= good. checked for resistance in EGR solenoid= none. checked for resistance in EGR sensor= 4.40 on the 20k scale. Is this a good reading?? My guess is this is how the PCM knows how far the EGR is open, but I don't know what the parameters are. :( This reading was taken with the engine off, and cold. Bad sensor? probably not. Stuck EGR/carbon buildup? maybe. Does the calibration update loosen the tolerances on the EGR performance??? Removal and cleaning sounds like a good start... What do you think Merlin?
Still no clue what P1300 is...

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