Vehicle: In this case the vehicle was a 2000 (NS) Chrysler Town & Country Minivan. Also applies to most vehicles.
Concern: A/C blows warm air at times.
Cause: Coolant leak from radiator was causing the engine to overheat. The PCM (engine computer) monitors engine temperature and disables the A/C compressor when coolant temperature rises above a predetermined level.
Resolution: Replaced the radiator and refilled cooling system.
Details: This is a perfect example of 'looking at the big picture. Diagnosis should begin with a general, common-sense visual inspection of the vehicle. If I had focused on the A/C system alone, the diagnosis would have taken much longer.
Vehicle: All vehicles. (JK)(ZJ)(CS)(JC)(TJ)(XJ)(PT)(KJ)(KK)(KA)(AN)(ND)(DR)(DS)(WJ)(WK)(XK)(LX)(LH)(FJ)(JR)(JS)(RT)(RS)(NS)
Concern: The MIL (check engine light) is on. The scan tool reveals DTC P0601 PCM internal controller failure.
Cause: The PCM (engine computer) has an internal fault.
Resolution: Replace the PCM to correct.
Details: This is an easy diagnosis. When P0601 is present, the solution is always to replace the PCM. There is no other possible cause. Normally the vehicle is still driveable.
Vehicle: All Chrysler, Jeep, and Dodge vehicles. (JK)(ZJ)(CS)(JC)(TJ)(XJ)(PT)(KJ)(KK)(KA)(AN)(ND)(DR)(DS)(WJ)(WK)(XK)(LX)(LH)(FJ)(JR)(JS)(RT)(RS)(NS)
Concern: Alternator failure. The alternator (generator) is not charging. Electrical problems.
Resolution: Hold on for a minute. Alternator failures are extremely rare on Chrysler, Jeep, and Dodge. You need to rule out the battery, wiring, and PCM first before replacing the alternator.
Details: The alternator is controlled by the PCM (engine computer). Again, true alternator failure is very rare. In ten years as a dealer service dept tech, I have replaced maybe five alternators.
Vehicle: 1996-1998 (ZJ) Jeep Grand Cherokee. 1996-2000 (NS) Chrysler Town & Country, Dodge Caravan
Concern: ABS light is on.
Cause: The pump motor circuit is not working properly.
Resolution: Use scan tool to check ABS codes - if code pump motor circuit not working properly is found replace ABS control module.
Details: You will need reverse torx socket to remove abs module. do not remove entire hydraulic control unit as you then have to bleed entire brake system.