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DTC codes / GM codes / P1698

P1698 · GMNo CCD Messages Received From PCM

P1698 on a GM vehicle means the Body Control Module (BCM) or another module on the Class 2 serial data bus has not received any messages from the Powertrain Control Module (PCM) over the Chrysler Collision Detection (CCD) bus for a set period. The computer detected a complete loss of communication from the PCM, not a single missed message, which points to a wiring, power, or PCM fault rather than a sensor problem.

SystemPowertrain
Code typeGM specific
SeverityHigh
Fix difficultyProfessional
AreaComputer and output circuits

Symptoms you may notice

  • The Service Engine Soon or Reduced Power warning light illuminates on the instrument cluster.
  • The engine may crank but not start, or start and immediately stall because the PCM cannot coordinate fuel and spark.
  • The transmission may default to a limp mode with harsh or delayed shifts.
  • The speedometer, tachometer, and other gauges may read zero or behave erratically.
  • Other modules may log communication codes, and the radio or climate control may act strangely.
  • Often no symptoms besides the warning light if the fault is intermittent and the PCM reconnects quickly.

Common causes, most likely first

  1. Broken, chafed, or corroded wires on the CCD bus circuit between the PCM and BCM, especially near connectors and harness bends.
  2. Poor terminal tension or water intrusion at the PCM or BCM connectors, causing an open on the bus line.
  3. Blown fuse or faulty relay in the PCM power or ground circuit, leaving the PCM unpowered.
  4. Failed PCM, often due to internal driver damage or water intrusion into the PCM housing.
  5. Failed BCM or another module on the bus that is shorting the CCD line and blocking all messages.
  6. Loose or corroded engine-to-chassis ground strap that interrupts the PCM ground reference.
  7. Aftermarket alarm or remote start wiring that has tapped into and damaged the CCD bus.

How to diagnose and fix it

  1. Connect a scan tool and check for communication with the PCM and BCM; note whether other modules also report lost communication.
  2. Inspect the PCM and BCM connectors for corrosion, pushed-out pins, and water intrusion, then clean and reseat them.
  3. Check the PCM power and ground circuits with a multimeter, including fuses, relays, and the engine ground strap.
  4. Measure resistance and voltage on the CCD bus wires between the PCM and BCM to find opens or shorts, wiggling the harness while watching the meter.
  5. Disconnect suspect modules one at a time to see if the bus communication returns, isolating a module that is shorting the line.
  6. If wiring and power checks pass, substitute a known-good PCM and verify communication before condemning the original unit.
  7. Clear the code and perform a road test to confirm the fault does not return, then repair any chafed harness sections permanently.

What P1698 Really Points To

  • P1698 is a bus communication code, so replacing the PCM first is a costly guess; the majority of these faults trace to a chafed wire or corroded connector on the CCD bus.
  • A weak or missing ground at the PCM can set this code even when the bus wiring is perfect, so always load-test the ground strap before condemning a module.
  • Aftermarket alarms, remote starters, and stereo installs that splice into the serial data line are a common hidden cause on older GM trucks and SUVs.
  • The code can be intermittent and set only when the vehicle is hot or vibrating over bumps, so a wiggle test of the harness while watching live data is essential.
  • Other modules may store their own lost-communication codes alongside P1698, and those companion codes help pinpoint which end of the bus is actually failing.

Can I keep driving with P1698?

Do not drive the vehicle if it cranks but will not start or stalls immediately, because the PCM is not controlling the engine. If the vehicle runs but the light is on, limit driving to a short trip to a repair shop and avoid highways, since the fault can cause a sudden stall or limp mode.

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 GM vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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