What does code P1538 mean?

Q: What does code P1538 mean?

A/C Request Circuit High Voltage. P1538 on a Chrysler vehicle means the powertrain control module (PCM) has detected an abnormally high voltage on the air conditioning request circuit, which is the wire that carries the driver's A/C demand signal from the HVAC control head to the PCM. The PCM expects a specific voltage range on this input, and a reading above the normal threshold tells it the circuit is likely open, shorted to voltage, or the switch contacts are not pulling the signal low as designed.

DTC codes / Chrysler codes / P1538

P1538 · ChryslerA/C Request Circuit High Voltage

P1538 on a Chrysler vehicle means the powertrain control module (PCM) has detected an abnormally high voltage on the air conditioning request circuit, which is the wire that carries the driver's A/C demand signal from the HVAC control head to the PCM. The PCM expects a specific voltage range on this input, and a reading above the normal threshold tells it the circuit is likely open, shorted to voltage, or the switch contacts are not pulling the signal low as designed.

SystemPowertrain

Code typeChrysler specific

SeverityLow

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Guidance is general and written for Chrysler vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.