Help with code P1621

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Help with code P1621

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Chevrolet Forums >> Chevy Trucks, Vans & SUV's >> Silverado >> Help with code P1621

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Help with code P1621 - 12/4/2007 9:46:21 AM

treetop

Posts: 8
Joined: 11/16/2007
Status: offline

Hi,
I've gotten a diagnostic code P1621 on my 02 Silverado. The clock keeps resetting most times I start up the truck. Now the seats and radio are forgetting their positions.
This started either when I reset my Change Oil warning, or when I installed a Bully Dog programmer. I'm in Ireland, so nobody here has a clue how to solve this isue. I've read what the code means, but am none the wiser as to what to do.
I'd be really grateful if you could give me some advice

Post #: 1

RE: Help with code P1621 - 12/5/2007 10:33:42 AM

dleonard2844

Posts: 95
Joined: 11/29/2007
Status: offline

I found this expaination on Wikianswers. com

"A vehicle control module (VCM) or powertrain control modules' (PCM) electronically erasable programmable read only memory (EEPROM) contains data essential to running the engine and transmission. The VCM/PCM stores critical preprogrammed data within the EEPROM, this data remains even if the vehicles' battery is disconnected. At power up the VCM/PCM checks the integrity of this data. If the checksum of the EEPROM does not match a predetermined value, DTC P1621 will set. The DTC will also set if the VCM/PCM is unable to correctly read or finds corrupt data from the EEPROM. GM recommends testing/replacement of the VCM/PCM using required equipment by a qualified technician for this type of VCM/PCM memory performance fault condition. "

I assume that what this basicly means is that your truck doesn't like what your Bullydog programmer did. First, Make sure the programmer you used is meant for your specific vehicle model and year. If not, get the right one and redo it. If it is the right one,Try resetting it back to factory programming and see if that fixes your problem. If that fixes it, get a differant programmer. let me know how that goes.

_____________________________

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(in reply to treetop)

Post #: 2

RE: Help with code P1621 - 12/7/2007 6:01:40 AM

treetop

Posts: 8
Joined: 11/16/2007
Status: offline

Thanks vety much for the good advice.

It seems that I should have removed a few fuses before I installed the programmer, which I didn't know at the time.
Now I've reset to stock, and still have the same problems. So I've gone and damaged the computer! Will probably never find somebody in Ireland to fix it. I just hope it hasn't messed up the timing or anything else important. Let his be a lesson to me.
Perhaps somebody knows a simple way to reset the computer?

(in reply to dleonard2844)

Post #: 3