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P0405 P1478 P1496 Diagnostic & PCM Issue - 2000 Chrysler 300M 3.5L V6

Model: 2000 Chrysler 300M 3.5 v-6 Fault Code: P0405 Posted: 2015-08-25 07:44

The engine runs roughly and stalls intermittently. Fault codes detected include P0405, P0122, P0108, P0118, P1478, and P1497 (indicating a low 5V supply output at the PCM). The EGR valve has already been replaced. At the PCM connector C2, B+ battery voltage is present, but no 5V or 8V reference signals are detected—specifically for the crankshaft and camshaft position sensors. This suggests a potential failure in the Powertrain Control Module (PCM). Additionally, upon inspection of sensor connectors (EGR, TPS, MAP), the 5V reference wires show a short to ground. When connector C1 at the PCM is unplugged, this short disappears; however, it returns when C1 is reconnected. This behavior strongly indicates an internal circuit fault within the PCM. I am considering replacing the PCM with a remanufactured unit and would like confirmation that this is indeed the root cause. Any insights or recommendations on diagnosing or resolving this issue would be greatly appreciated. diamondjim

Related fault codes
P0405P1478P1496
Comments (2)
Anonymous 2015-08-25 15:09

Any additional observations? Cruise control not functioning, no bus communication, and no history of flooding. Check the reference wires at CKP and CMP sensors—does voltage appear on the reference (typically the ORG wire)? Repeat for TPS, EGR, MAP, and AC transducer (likely PPL wire). TPS and AC transducers are known common failure points in this model.

Anonymous 2015-08-26 13:25

kev2—no further additions. I haven’t used cruise control recently and believe it’s functioning normally. The term 'bus' likely refers to the vehicle's communication network, which has not been affected by flooding. As for reference wires, no voltage is present on them or at the PCM connector plugs. I’ve only tested the crankshaft and camshaft sensor references at the PCM—no 8V signal detected there either. Given this information, I would have likely bypassed replacing the EGR valve, though it poses no harm. Thanks for your input. diamondjim