got 02 zr2 that SES light on,it had code read and is showing p1638 . called buddy at dealer, he tells me that it is the computer going . read swartlkk s post in code section and just did not understand the info . he is saying that "F" terminal on generator is bad . not trying to be a smart a@# but the last thing i worked on that had a generater was made in the 60s . if someone can explain it different or more simplified it is greatly appreciated .

 

Are you confusing P1638 with P1683? One of the codes for a driver in the PCM going bad is P1683.

 

could be will have to get the code reread to verify

 

code is P1683 sorry

 

Been there, done that. You'll have to see the Chevy dealer for PCM reprogramming and/or replacement.

 

Yeah, that isn't a good code. Sounds like you'll be taking a trip to the dealer soon.

And on the generator/alternator ****-ness . Look at most of the FSMs... The alternator is still referred to as 'generator' in MANY different places.

 

when i had code read it also kicked out thermostat code P0128 . replaced thermostat and SES light is off. everything seems to be working ok. should i have code cleared and drive on or do i get it checked out at dealer eat the cost of going there and hope its not major deal? decisions , decisions ? thanks for any help

 

I would wait and see if the light comes back and if the code is still P1683, you know what to do.

 

if i am not mistaken the code will remain in memory . just clairifying on generator - alternator terms .

 

A battery disconnect will reset the current codes. History will remain unless cleared by a scan tool.