OBD Code P1698: No CCD Messages From TCM – Causes & Fixes

What Does P1698 Mean?

P1698 is a Dodge/Chrysler-specific diagnostic trouble code that indicates a communication failure between the powertrain control module (PCM) and the transmission control module (TCM) on the CCD (Chrysler Collision Detection) bus. The CCD bus is a two-wire communication network used by Dodge and Chrysler vehicles to allow various control modules to share data and coordinate vehicle operation.

When the PCM stops receiving messages from the TCM for a specified period (usually several seconds), it sets this code and illuminates the check engine light. This is a serious communication issue that can affect transmission operation, fuel economy, and overall vehicle performance.

What Does Code P1698 Mean? (Technical Explanation)

The CCD (Chrysler Collision Detection) bus is a serial communication network that allows the PCM, TCM, ABS module, and other control modules to exchange real-time data. The TCM constantly sends information about transmission status, gear selection, fluid temperature, and shift commands to the PCM.

When the PCM does not receive CCD messages from the TCM within the expected timeframe, it recognizes this as a communication fault and stores code P1698. This can occur due to:

• Broken or corroded CCD bus wiring
• Faulty TCM unable to transmit
• Poor ground connections on the TCM or PCM
• CCD bus termination resistor failure
• PCM unable to receive on the CCD bus

Unlike many other DTCs, P1698 is specific to Dodge and Chrysler vehicles from the 1990s and 2000s that use the CCD bus architecture.

Common Symptoms

• Check Engine Light: Illuminated on the dashboard
• Transmission Issues: Hard shifts, delayed shifts, or inability to shift properly
• Limp Mode: Vehicle may enter reduced power mode or transmission defaults to safe mode
• Poor Fuel Economy: Transmission unable to optimize shift points
• No Overdrive: Transmission may not engage overdrive gear
• Erratic Shifting: Unpredictable or harsh gear changes
• Stalling or Hesitation: Engine may stumble during acceleration
• No Communication with Scan Tool: Difficulty reading TCM data through diagnostic scanner

Possible Causes (Ranked by Frequency)

1. Corroded or Damaged CCD Bus Wiring

The CCD bus uses two wires (CCD+ and CCD-) that run throughout the vehicle. Corrosion, water intrusion, or physical damage to these wires is the most common cause of P1698. Check under the dashboard, around the engine bay, and along the frame for damaged insulation or green/white corrosion on connectors.

2. Faulty Transmission Control Module (TCM)

A failing or dead TCM cannot transmit CCD messages to the PCM. This is the second most common cause. The TCM may have internal circuit board damage, failed capacitors, or a dead microprocessor.

3. Poor Ground Connection

Both the TCM and PCM require solid ground connections to operate properly. Loose, corroded, or missing ground straps can prevent the TCM from communicating on the CCD bus. Check all ground connections at both modules.

4. Faulty PCM

Less common, but a failing PCM may lose the ability to receive CCD bus messages even if the TCM is transmitting correctly. This is usually confirmed only after all wiring and TCM issues are ruled out.

5. CCD Bus Termination Resistor Failure

The CCD bus uses termination resistors at each end to prevent signal reflection. A failed resistor can disrupt communication on the entire bus. These are typically located in the PCM or TCM.

6. Corroded or Loose Connectors

CCD bus connectors at the PCM, TCM, and intermediate junction points can corrode or loosen, breaking communication. This is especially common in older vehicles or those exposed to salt and moisture.

Diagnostic Steps

Step 1: Verify the Code with a Scan Tool

Connect a diagnostic scan tool to the OBD-II port and confirm code P1698 is present. Check for any additional DTCs that may provide additional clues (such as P1699 or other CCD bus codes). Note the freeze frame data, which shows engine conditions when the code was set.

Step 2: Perform a Visual Inspection

Inspect all visible wiring and connectors related to the CCD bus:

• Look for corroded, damaged, or pinched wires
• Check connector pins for corrosion (green or white discoloration)
• Verify all connectors are fully seated and locked
• Look for water intrusion or moisture in connector cavities
• Inspect ground straps for corrosion or looseness

Step 3: Check CCD Bus Voltage

Using a digital multimeter, measure the voltage on the CCD+ and CCD- wires at the PCM connector:

• With the ignition off, there should be approximately 2.5V on each wire
• With the ignition on, voltage should remain stable
• If voltage is 0V or 5V, there’s a wiring or module problem
• If voltage fluctuates wildly, check for a short circuit

Step 4: Test CCD Bus Continuity

Disconnect the PCM and TCM connectors. Using a multimeter set to resistance (ohms):

• Measure continuity between CCD+ pins at the PCM and TCM connectors
• Measure continuity between CCD- pins at the PCM and TCM connectors
• There should be less than 1 ohm of resistance if wiring is good
• If resistance is infinite, there’s a broken wire or bad connector

Step 5: Check Ground Connections

Verify solid ground connections:

• Measure resistance between the TCM case and vehicle ground (should be less than 0.1 ohms)
• Measure resistance between the PCM case and vehicle ground
• Check the battery negative terminal connection to the engine block
• Clean and tighten any corroded ground straps

Step 6: Scan for TCM Communication

Using your scan tool, attempt to read TCM data:

• If the scan tool can communicate with the TCM, the TCM is likely functional
• If the scan tool cannot communicate with the TCM, the module may be faulty
• Check for any TCM-specific DTCs that may indicate internal failure

Step 7: Repair or Replace as Needed

Based on your diagnostics:

• If wiring is damaged: Repair or replace the CCD bus wiring harness
• If connectors are corroded: Clean connectors with electrical contact cleaner or replace connector assemblies
• If ground is poor: Clean and re-seat ground straps; replace if necessary
• If TCM won’t communicate: Replace the TCM (may require reprogramming)
• If PCM won’t communicate: Replace the PCM (will require reprogramming)

Repair Cost Estimates

The cost to repair P1698 varies significantly depending on the root cause:

• Wiring Repair/Replacement: $150–$400 (parts and labor)
• Connector Cleaning/Replacement: $100–$300
• Ground Strap Replacement: $50–$200
• TCM Replacement (used/refurbished): $300–$800 plus programming
• TCM Replacement (new OEM): $800–$1,500 plus programming
• PCM Replacement (used/refurbished): $400–$1,000 plus programming
• PCM Replacement (new OEM): $1,000–$2,000 plus programming

Note: Many shops will start with a thorough wiring and connector inspection before recommending module replacement, as this often resolves the issue at a fraction of the cost.

Can I Still Drive?

Severity: Moderate to High

You can technically drive a vehicle with code P1698, but it’s not recommended for extended periods:

• Short Trips: Safe for short distances to a repair shop
• Transmission Function: The transmission may operate in a default or “safe” mode, which can cause harsh shifts and reduced performance
• Fuel Economy: Expect significantly worse fuel economy due to improper shift timing
• Drivability: The vehicle may hesitate, stall, or be difficult to start
• Risk of Damage: Prolonged driving without proper TCM communication can cause transmission damage
• Emissions: The vehicle may fail emissions testing

We recommend having this code diagnosed and repaired as soon as possible to avoid further damage to the transmission and engine.

Frequently Asked Questions