Code P1693 is a manufacturer-specific diagnostic trouble code used by Dodge and Chrysler vehicles to indicate that the primary engine control module (ECM) has detected a stored diagnostic trouble code in a companion module—such as the transmission control module (TCM), body control module (BCM), or anti-lock brake system (ABS) module. This code signals a communication or data integrity issue between vehicle control modules on the CAN (Controller Area Network) bus.
What Does P1693 Mean?
P1693 is a Dodge/Chrysler-specific code that translates to “DTC Present in Companion Module.” Rather than indicating a direct problem with the engine, transmission, or brakes, this code alerts you that:
- The engine control module has successfully communicated with another vehicle control module (companion module)
- That companion module has stored at least one diagnostic trouble code
- The engine control module is reporting this condition to alert the technician
This is essentially a “messenger” code—the ECM is telling you that another module in the vehicle has a problem that needs diagnosis. The actual issue could be in the transmission, ABS system, body electronics, or another networked module.
Common Symptoms
- Check Engine Light (MIL) illuminated – The primary indicator that P1693 is stored
- Transmission shifting issues – Hard shifts, delayed engagement, or limp mode if the TCM has a fault
- ABS warning light – If the fault is in the ABS module
- Traction control light – Often linked to ABS or stability control faults
- Body control module faults – Power window, door lock, or lighting issues
- No drivability symptoms – Vehicle may run normally despite the code, as P1693 is often a secondary code
- Multiple warning lights – Several module fault indicators may appear simultaneously
Possible Causes
- CAN Bus Communication Fault (Most Common) – Damaged, corroded, or loose connectors on the CAN bus wiring that links all vehicle modules. This is the #1 cause in Dodge Ram and Dakota trucks.
- Faulty Companion Module – The transmission control module, ABS module, or body control module itself may be defective and generating the stored code.
- Wiring Issues Between Modules – Broken, pinched, or corroded wiring in the CAN bus harness, especially in areas prone to heat or moisture.
- Outdated Module Software – Companion modules may have outdated firmware that causes communication errors or false fault codes. This is common in 2005-2010 Dodge Ram trucks.
- Battery Voltage Issues – Low battery voltage or alternator problems can cause modules to malfunction and generate fault codes.
- ECM Software Corruption – Rarely, the engine control module’s software may be corrupted, causing it to misinterpret data from companion modules.
- Aftermarket Module Installation – Non-OEM modules or poorly integrated aftermarket electronics can cause communication conflicts.
Diagnostic Steps
Step 1: Retrieve All Diagnostic Codes
- Use an OBD-II scanner to read all stored and pending codes from every module (ECM, TCM, ABS, BCM, etc.)
- Write down all codes, not just P1693—the companion module will have its own codes
- This tells you which module is actually faulty
Step 2: Inspect CAN Bus Connectors and Wiring
- Locate the CAN bus connectors (typically near the firewall or under the dashboard)
- Check for corrosion, moisture, or loose pins
- Look for damaged insulation or pinched wires in the CAN harness
- Pay special attention to areas near the engine bay where heat and moisture are present
Step 3: Check Battery and Charging System
- Test battery voltage (should be 12.6V at rest, 13.5-14.5V while running)
- Use a multimeter to check alternator output
- Low voltage can cause module communication errors
Step 4: Perform Module Communication Test
- Use a professional OBD-II scanner (Chrysler-specific if possible) to test CAN bus communication
- Some scanners can perform a “module scan” to verify all modules respond correctly
- This will identify if the communication issue is intermittent or constant
Step 5: Update Module Software
- Check Chrysler’s technical service bulletins (TSBs) for software updates for the affected companion module
- This is especially important for 2005-2010 Dodge Ram trucks, which had known TCM and ABS software issues
- Software updates often resolve communication faults without requiring hardware replacement
Step 6: Test-Drive and Clear Codes
- After repairs, clear all codes and perform a test drive
- Monitor for code recurrence over several drive cycles
- If P1693 returns, the underlying companion module fault wasn’t resolved
Repair Cost Estimates
DIY Diagnosis: $0–$50 (OBD-II scanner rental)
Professional Diagnosis: $75–$150 (1–2 hours of labor)
CAN Bus Connector Repair/Replacement: $100–$400
- Cleaning corroded connectors: $100–$200
- Replacing damaged CAN harness: $200–$400
Module Software Update: $50–$200
- Often the cheapest fix if available
- Many dealerships offer this as a warranty repair
Companion Module Replacement: $300–$1,200+
- Transmission Control Module (TCM): $400–$800
- ABS Module: $300–$600
- Body Control Module (BCM): $200–$500
- Includes programming and calibration
Total Repair Range: $100–$1,500+ depending on root cause
Can I Still Drive?
Severity: Moderate
Yes, you can typically continue driving with P1693, but with caution:
- Safe to Drive Short Distances: The code itself doesn’t disable critical functions, and your vehicle will likely operate normally
- Check the Companion Module’s Fault: If the companion module’s code is transmission-related, you may experience harsh shifts or limp mode. If it’s ABS-related, your anti-lock brakes may be disabled. Review the specific codes in the other modules.
- Don’t Ignore It: P1693 indicates a communication problem that could worsen. Module communication failures can eventually affect engine performance, transmission operation, or safety systems.
- Get It Diagnosed Soon: Have the vehicle scanned at a Chrysler/Dodge dealership or qualified technician within a few days to identify the root cause.
- Avoid Long Trips: Don’t take extended highway drives until the issue is resolved, especially if the fault is in the transmission or ABS module.
Frequently Asked Questions
Q: What’s the difference between P1693 and a code in the companion module itself?
A: P1693 is stored in the engine control module and indicates that another module has a fault. The companion module will have its own specific code (like P0700 for transmission faults or P0500 for ABS issues). You need to retrieve codes from all modules to find the actual problem. P1693 is just the messenger telling you to look elsewhere.
Q: Can P1693 be caused by a dead battery?
A: Indirectly, yes. A weak or recently replaced battery can cause modules to lose communication temporarily, generating P1693. However, once the battery is fully charged and the vehicle runs normally, the code should clear. If it returns, there’s a deeper communication or module issue. Always check battery health and alternator output first.
Q: Will clearing P1693 fix the problem?
A: No. Clearing the code without addressing the root cause will only temporarily hide the problem. The code will return within a few drive cycles if the underlying issue (faulty connector, bad module, software bug) isn’t fixed. Always diagnose before clearing.
Q: Is P1693 covered under Chrysler warranty?
A: If your vehicle is under the powertrain warranty (typically 5 years/60,000 miles for Dodge), module communication faults and software updates are usually covered. However, if the fault is due to water damage, accident damage, or aftermarket modifications, it may not be covered. Contact your Dodge dealership to verify.
Q: Why do Dodge Ram trucks get P1693 so often?
A: 2005-2010 Dodge Ram trucks are notorious for CAN bus communication issues, particularly with the transmission control module. This is often due to corroded connectors in the engine bay and known TCM software bugs. Chrysler released several TSBs (Technical Service Bulletins) addressing this issue. If you own a Ram truck with P1693, have the CAN connectors inspected and update the TCM software.