Code
P1696
JEEP
P — Powertrain
PCM Failure EEPROM Write Denied
Views:
UK: 28
EN: 63
RU: 79
AI status
Completed
Completed
100%
Causes
- Failed or corrupted PCM internal EEPROM/memory
- Low or unstable battery voltage during PCM write/reprogramming
- Poor power or ground connections to the PCM
- Faulty or damaged PCM connector or wiring (power, ground, CAN, serial)
- Interrupted or incompatible programming attempt (tool, software, or procedure)
- Anti-theft/immobilizer preventing ECM/PCM reprogramming
Symptoms
- Malfunction Indicator Lamp (MIL) or service light illuminated
- Stored P1696 in PCM fault memory (may be accompanied by other codes)
- Inability to complete PCM reflash or module programming
- Intermittent or no communication with PCM using scan tools
- Vehicle may display drivability issues, limp-home mode, or not start depending on affected functions
What to check
- Read and record all stored codes and freeze frame data from all modules
- Verify battery voltage: fully charged battery and >12.4 V at key-on; >13.5 V with engine running
- Inspect PCM connector and harness for corrosion, bent pins, water intrusion, or damage
- Check PCM power and ground circuits for proper voltage and low resistance
- Verify CAN/communication bus integrity (check for other modules with communication faults)
- Confirm no active anti-theft/immobilizer faults that could block programming
Signal parameters
- Key-on battery voltage (should be stable and within specified range)
- Ignition-switched 12V supply to PCM (voltage present and stable)
- PCM ground circuit resistance to battery negative (low ohms)
- CAN high/low voltages and bus idle voltages (~2.5 V nominal differential behavior)
- Module wake/response when addressed by scan tool (response time and presence)
- Communication error counters or timeout values reported by scan tool during programming
Diagnostic algorithm
- Retrieve all DTCs and freeze frame data from PCM and other modules; note any related communication codes.
- Verify battery state of charge and charging system; recharge or load-test battery if voltage is low.
- Inspect PCM connector, wiring harness, and grounds; repair any corrosion, loose terminals, or damaged wires.
- Check power and ground presence at the PCM with key ON and engine RUN; measure voltages and ground resistance.
- Scan CAN/serial network for communication errors; repair any network faults before further programming attempts.
- If vehicle was being programmed, confirm correct tool, software version, and follow OEM programming procedures (including required battery voltage and ignition state).
- Attempt to clear codes and perform a controlled reflash/repair using the factory scan tool. Ensure battery maintained by battery charger or power supply during reflash.
- If reflash fails repeatedly and wiring/power/communication are confirmed good, consider PCM internal EEPROM failure — consult OEM for confirmatory tests and replacement procedure.
- If PCM is replaced or reprogrammed, perform any required immobilizer/keysoss/learn procedures and recheck for related codes and correct operation.
- After repair or reflash, road-test and re-scan to confirm the fault does not return.
Likely causes
- Battery voltage dropped or was unstable during a programming event
- Loose/poor ground at PCM causing write failure
- Corrupted EEPROM inside the PCM (internal hardware failure)
- Failed or incomplete reflash with incompatible software or tool
- Open/shorted power supply or data lines to PCM
Fault status
Status
PCM EEPROM Write Denied - internal memory/programming write failed or was blocked.
Repair difficulty: Hard
Diagnostic time: 1.5-3.0 hours
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