Is it the PCM or just several problems

Asked by Jan 07, 2017 at 04:31 AM about the 2008 Chevrolet Silverado 1500 LT1 Crew Cab

Question type: Maintenance & Repair

So about a month ago I was driving and as I was
accelerating my truck shifted hard than my check
engine light started flashing now I have 7 different
codes that came on at the same time one is device
voltage low another is device voltage high than I
have two codes for the same misfire on cylinder 7
than I also have a code for my EVAP and another
for the generator which I already replaced and after
letting my computer reset the truck started fine ran
for about a minute than started misfiring again do
y'all think it's a computer or something else

1 Answer

100,475

If you didn't use a good scan tool to reset the computer it didn't reset properly, the problem sounds like it is thermally related so the misfire could be anything from a sensor out of specs to an internal engine vacuum leak on number 7. Don't disconnect the battery to reset the ECM you could cause the BCM to loose the factory presets and then some if not all of the accessories will stop working. Have the ECM cleared properly then drive it around until the light comes back on and then have the codes rechecked, most parts stores can do this, and then these codes will be fresh codes and not past memory codes that may or may not have been viable due to unstable power supply. You may want too buy a preset saver tool from your local parts store, it uses a 9 volt battery and plugs into a working lighter or power port. Better ones plug directly into the OBD2 port and use a external power supply like a jump box. And please make sure the grounds are good, especially the sensor grounds. like they say basics first.

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