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DTC codes / Chrysler codes / P1694

P1694 · ChryslerNo CCD Messages Received From ECM

P1694 means the powertrain control module (PCM) has not received any valid messages from the engine control module (ECM) over the Chrysler Collision Detection (CCD) bus for a set period. The PCM monitors the CCD data bus and sets this code when the expected periodic messages from the ECM are missing, indicating a communication failure between the two modules.

SystemPowertrain
Code typeChrysler specific
SeverityHigh
Fix difficultyProfessional
AreaComputer and output circuits

Symptoms you may notice

  • The malfunction indicator lamp (MIL) illuminates on the instrument cluster.
  • The engine may crank but fail to start because the PCM lacks fuel and spark scheduling data from the ECM.
  • The engine may start and run in a limp-home mode with reduced power or fixed timing.
  • The transmission may shift harshly or stay in a default gear due to missing ECM data.
  • The speedometer, tachometer, or other dashboard gauges may be inoperative or erratic.
  • Often no symptoms besides the warning light if the fault is intermittent.

Common causes, most likely first

  1. Open or shorted CCD bus wiring between the ECM and PCM, often at a connector or splice.
  2. Failed ECM not transmitting on the CCD bus due to internal fault or loss of power/ground.
  3. Failed PCM not receiving or processing CCD messages correctly.
  4. Corroded, loose, or damaged terminals at the ECM or PCM connectors.
  5. Blown fuse or faulty relay supplying power to the ECM.
  6. Poor ground connection at the ECM or PCM mounting points.
  7. Aftermarket accessories or radio equipment interfering with the CCD bus signal.

How to diagnose and fix it

  1. Verify battery voltage and condition, then check all fuses and relays feeding the ECM and PCM.
  2. Inspect the ECM and PCM connectors for corrosion, loose pins, or pushed-out terminals and repair as needed.
  3. Perform a voltage drop test on the ECM and PCM ground circuits to confirm clean, tight grounds.
  4. Use a scan tool to check for communication with the ECM on the CCD bus; if no communication, proceed to bus diagnostics.
  5. Measure resistance and voltage on the CCD bus wires (typically two twisted wires) with the ignition off and on, looking for opens, shorts, or excessive bias voltage.
  6. Substitute a known-good ECM or PCM only after confirming wiring integrity, then retest for the code.
  7. Clear codes and perform a road test to confirm the repair and ensure no other modules set communication codes.

CCD Bus Faults That Mimic ECM Failure

  • A failed crankshaft or camshaft position sensor can prevent the ECM from sending messages, leading to P1694 without any ECM fault code stored.
  • The CCD bus is sensitive to aftermarket electrical noise; a poorly installed stereo amplifier or alarm can corrupt messages and set this code intermittently.
  • Many technicians replace the ECM first, but a single chafed wire in the harness near the exhaust manifold is a more common cause on older Chrysler vehicles.
  • P1694 can be set by a low battery or a recent jump-start that momentarily dropped bus voltage, so always check for a stored history code before condemning a module.
  • The CCD bus uses a bias voltage that can be measured with a voltmeter; readings outside the normal 0.5 to 4.5 volt range on either wire point to a wiring fault rather than a module failure.

Can I keep driving with P1694?

Do not drive the vehicle if it fails to start or runs in limp mode, as the ECM may not be controlling fuel and spark correctly. If the engine starts and runs normally with only the warning light on, limit driving to a short trip to a repair shop and avoid heavy loads or high speeds.

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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