Hey Scotty, everyone. My grandmother has a 2004 Chrysler Pacifica v6 2wd. It has a battery drain and I found that it is the power seat fuse causing the drain. Is there any way to diagnose if the module isn't shutting down properly or if it needs to be replaced?
The easiest way to see if the Memory Heated Seat/Adjustable Pedal Module (MHSAPM) ((with heated seats option)) or the Memory Seat/Adjustable Pedal Module (MSAPM) ((without the heated seat option)) (((let's just refer to it as the "Seat Module))) isn't going to sleep is to use a bidirectional scanner that can communicate with the Seat Module to see if it's setting any codes or getting/sending any requests on the PCI network.
Back in 2004 you'd need a dealer level DRB III scanner to do that. Now you can find a scanner in the $300 range which can access these Chrysler PCI network (low priority) modules like the seat and door modules.
Another way is to hook up a scope to the PCI network at the Data Link Connector (Pin 2) and look for activity on the bus. If there is activity, unplug the Power and Ground connector to the Seat Module and see if the activity stops.
But maybe a more likely reason for the parasitic draw is because the Seat Module has an internal short. There was a CSN from Chrysler about the Seat Module getting fried from electrostatic discharge on those Pacificas that came with cloth seats. It seems to assume the damage would cause an open in a circuit on the pcb resulting in the seat controls not working but maybe the damage in yours is just enough of a short on the pcb to cause a parasitic draw. And even if you don't have cloth seats it seems that Seat Module is pretty fragile when it comes to static discharges. (the CSN is kind of funny because not only do they replace the Seat Module ((which had a beefier Ground)) but they changed the drivers door handle to a material less electrically conductive.
Anyway, maybe try disconnecting the Power and Ground connector on the Seat Module just to make sure the draw is coming from the Module and not from a problem in the wiring going to it. They're the Orange with Red stripe and the Black with Orange stripe wires on the C4 connector on the Seat Module. (disconnect the battery negative cable first just to be on the safe side)
On the left side of the picture:
You need a wiring diagram for these kind of problems. Try searching the internet.
hey @jack62 thanks for the input. tested the PCI (pci bus?) and it was getting 5-6v before I unplugged the module under the seat. After unplugging it, the PCB was reading under a volt to 1.5v. Going to try swapping out the module. the drain is gone after unplugging the module.