Chrysler Neon 1995-1999 Repair Guide

Powertrain Control Module (PCM)

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OPERATION



See Figures 1, 2, 3 and 4

The heart of the electronic control system, which is found on the vehicles covered by this guide, is a Powertrain Control Module (PCM). The module gathers information from various sensors, then controls fuel supply and engine emission systems. The PCM controls the engine and related emissions systems. It may also control the manual transaxle shift lamp or the shift functions of the electronically controlled automatic transmission.

Care must be taken when handling these expensive components in order to protect them from damage. Carefully follow all instructions included with the replacement part. Avoid touching pins or connectors to prevent damage from static electricity.



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Fig. Fig. 1: The PCM is attached to the inner fender panel, next to the windshield washer bottle-1995 vehicle shown


WARNING
To prevent the possibility of permanent control module damage, the ignition switch MUST always be OFF when disconnecting power from or reconnecting power to the module. This includes unplugging the module connector, disconnecting the negative battery cable, removing the module fuse or even attempting to jump your dead battery using jumper cables.

In the event of an PCM failure, the system will default to a pre-programmed set of values. These are compromise values which allow the engine to operate, although at a reduced efficiency. This is variously known as the default, limp-in or back-up mode. Driveability is almost always affected when the PCM enters this mode.



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Fig. Fig. 2: Powertrain Control Module (PCM) 60-way connector identification-1995 vehicles



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Fig. Fig. 3: PCM 40-pin terminal identification (1 of 2)-1996-99 vehicles