Notes On Intermittents

If battery has been disconnected for any reason, Codes P052 and P109 will set. PCM keeps a running check on the memory, if memory changes it resets. Codes P052 and P109 may also set while keying OFF in diagnostics. If IPC is sending new information to PCM when ignition switch is turned off, making PCM think it has been switched off, causing a reset.

Fig 1: Code P052 & P109 Schematic, PCM Keep Alive Memory Reset

Courtesy of GENERAL MOTORS CORP.