code P1682.
no new parts or pieces installed. I unplugged ECM2 to check green wire from Evap solenoid to pin 8. I disconnected neg battery cable then pulled the junction/fuse block out to check red/pink wire from Evap solenoid to connector plug under the fuse block. Both wires were good. I plugged the junction block back in reconnected the battery and now get "engine power is reduced" and code P1682. It seems to try to start then dies like fuel is cut off. I have pulled and tested nearly every fuse and relay on the block, even if they seem to have nothing to do with the problem.

I have had the service traction control / stabilitrack warning in the past but not recently. This all came about after my mechanic replaced the Evap solenoid twice cleared the codes and the check engine light still came back on after driving it 10-15 miles. He told me it was a wire/electrical problem but didn't tell me what code it gave (P0446/P0443). I took the task of tracing wires upon my self after he told me it would be fine to drive.

 

Check for bent pins and use a electrical contact cleaner/lube in connectors.

P1682 CHEVROLET Possible Causes

What does this mean?

• Faulty ignition switch
• Ignition Switch harness is open or shorted
• Ignition Switch circuit poor electrical connection
• Faulty Engine Control Module (ECM)

 

You should verify the performance of the ign sw.
If for instance the PCM doesn't get the proper power, it could have a problem with providing the 5 volt reference voltage to the system.

 

OK, so after a few days of shade tree tinkering......
I was convinced I blew an integrated relay in the junction block. I got really lucky and found one because GM no longer makes them. New block in hand I compared the two. That's when I found fuse 35, 2amp DLIS (key ignition system and theft deterrent system), was bad on the old block. On top of everything else I was using my key that is so worn out it only works if you put it in the switch a certain way.
So this is what I did.
step 1= New Junction block
step 2 = new vapor canister vent valve solenoid
step 3 = fuse 35 good,
step 4 = charged the battery
step 5 = get the good key
step 6 = PRAY
I'm pretty sure praying did the most good but my Tahoe is back in working order. This all originally came about because my mechanic didn't want to look deeper into a P0449 code because he replaced the Vapor Canister Purge Solenoid twice. After a 10 mile test drive no check engine light yet.