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DTC codes / Chrysler codes / P1602

P1602 · ChryslerPCM Not Programmed

P1602 on a Chrysler vehicle means the Powertrain Control Module (PCM) has not been programmed with the correct operating software, so it cannot run the engine or transmission properly. The computer detected that its flash memory is blank or contains an invalid calibration, which typically happens after a module replacement or a failed reprogramming event.

SystemPowertrain
Code typeChrysler specific
SeverityHigh
Fix difficultyProfessional
AreaComputer and output circuits

Symptoms you may notice

  • The engine may crank but not start, or start and immediately stall because the PCM has no fuel and spark strategy loaded.
  • The check engine light or a red security light may illuminate, and the vehicle may refuse to stay running.
  • The transmission may default to a limp mode or fail to shift if the PCM calibration is missing.
  • Often no symptoms besides the warning light if the PCM has a partial or mismatched calibration that still allows the engine to run.
  • A no-start condition after battery replacement, PCM replacement, or a dealer reprogramming attempt that was interrupted.
  • The scan tool may fail to communicate with the PCM or report that no calibration file is present.

Common causes, most likely first

  1. A new or replacement PCM was installed without flashing the correct Chrysler calibration file for the vehicle's VIN and options.
  2. The PCM reprogramming procedure was interrupted by a battery drain, power loss, or scan tool disconnect, leaving the flash memory incomplete.
  3. The PCM was swapped from another vehicle and never reprogrammed to match the current vehicle's VIN, engine, and transmission configuration.
  4. A failed or corrupted PCM internal flash memory that will not accept a new calibration during programming.
  5. Low battery voltage during a programming event caused the PCM to abort and leave the module unprogrammed.
  6. A wiring or communication fault on the CAN bus prevented the scan tool from completing the flash procedure.
  7. Aftermarket or salvage PCM installed without a dealer-level flash, which is common on older Chrysler products.

How to diagnose and fix it

  1. Verify battery voltage is at least 12.5 volts and connect a stable power supply before any programming attempt, because low voltage is the most common cause of a failed flash.
  2. Use a Chrysler-capable scan tool to read the PCM part number and confirm whether a valid calibration is present; if the tool reports no calibration, programming is required.
  3. Obtain the correct calibration file for the vehicle's VIN from a dealer or a subscription programming service and flash the PCM following the manufacturer's procedure exactly.
  4. If programming fails repeatedly, check the CAN bus wiring and PCM power and ground circuits for opens, shorts, or corrosion before condemning the module.
  5. If the PCM will not accept a calibration after verifying power and communication, replace the PCM with a new or remanufactured unit and program it to the vehicle.
  6. After successful programming, clear the code, perform a relearn or initialization procedure if required, and verify the engine starts and runs with no stored codes.
  7. Road test the vehicle through several drive cycles to confirm the PCM retains the calibration and P1602 does not return.

Why a fresh PCM still sets P1602

  • A brand-new PCM out of the box is blank and will set P1602 until it is flashed with the correct calibration for the vehicle's VIN, engine, and options, so installing it without programming guarantees the code.
  • Many P1602 cases are caused by a failed programming attempt rather than a bad PCM, and simply reflashing with a stable power supply resolves the fault without replacing any parts.
  • A salvage or used PCM from another Chrysler vehicle will set P1602 because the calibration does not match the current vehicle's configuration, even if the part number looks identical.
  • Some Chrysler vehicles will start and run with a mismatched calibration, so the only clue is the warning light and a scan tool report of an unprogrammed or invalid PCM, which is easy to misdiagnose as a sensor fault.
  • The code does not always mean the PCM is defective; a communication fault on the bus during programming can leave the module unprogrammed and set P1602 even though the hardware is fine.

Can I keep driving with P1602?

Do not drive the vehicle with P1602 because the PCM may have no valid fuel, spark, or transmission strategy, which can cause a no-start, stalling, or unsafe limp mode. Have the vehicle programmed or towed to a repair facility before attempting normal driving.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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

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