No CCD/J1850 Bus Message From PCM (Chrysler)
What does P1694 mean?
The P1694 code means the vehicle's onboard diagnostic system has detected: No CCD/J1850 Bus Message From PCM (Chrysler). This is a critical severity code.
Common Symptoms
- Multiple warning lights on dashboard
- Engine may not start
- No communication with PCM on scan tool
- Instrument cluster gauges inoperative
- Multiple systems not functioning
Probable Causes (Ranked by Likelihood)
- Failed PCM Very High
- Broken CCD bus wiring High
- Corroded bus communication connector Moderate
- Shorted bus network pulling down communication Low
Step-by-Step Diagnostic Procedure
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Attempt to communicate with the PCM using a scan tool. No response confirms communication failure.
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Measure CCD bus voltage at the diagnostic connector (should be approximately 2.5V on each bus wire).
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Inspect the PCM connector and bus wiring for corrosion, breaks, or water damage.
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Disconnect other modules one at a time to see if a shorted module is pulling down the bus.
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Verify PCM power and ground circuits are within specification before condemning the PCM.
Frequently Asked Questions
What is the CCD bus?
The CCD (Chrysler Collision Detection) bus is the communication network used in older Chrysler vehicles to allow modules to share data. Newer models use CAN bus instead.
Can a single bad module prevent all communication?
Yes. If one module on the bus shorts the communication line, it can prevent all modules from communicating. Disconnecting modules one at a time can isolate the fault.
Do I need to reprogram the PCM after replacement?
Yes. A replacement PCM must be programmed with the correct vehicle calibration and may need to have keys and immobilizer reprogrammed as well.