How to Fix Diagnostic Code P1683

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šŸšØ Diagnostic Profile

Vehicle Make: Chrysler

Fault Description: Speed Control Power Relay Or Speed Control 12 Volt Driver Circuit Open Or Shorted

This fault indicates the cruise control system’s power supply or 12V driver circuit is either interrupted (open) or grounded/shorted. On most Chrysler, Dodge, and Jeep platforms using a PCM-integrated speed control relay, this circuit energizes the vacuum/electric servo or electronic throttle actuator that maintains set speed. The PCM monitors this driver circuit for proper voltage switching; an open condition prevents cruise engagement, while a short to ground can set the code immediately upon relay energization and may also blow the associated fuse. Confirm the exact model, year, and engine on the master technician’s work order before proceeding, as relay and fuse locations vary between the Power Distribution Center (PDC), Integrated Power Module (IPM), or Totally Integrated Power Module (TIPM) depending on platform generation.

šŸšØ Repair Difficulty Tier

Tier: [Intermediate]

Relay replacement is straightforward, but isolating an open or shorted 12V driver circuit requires a digital multimeter, a wiring diagram, and familiarity with reading DTC freeze-frame data. Circuit repairs involving harness access may require removing interior trim, kick panels, or portions of the PDC/TIPM harness connector to access the speed control driver wire run to the PCM.

šŸ› ļø Resolution Steps

Step 1: Preliminary Inspection

  • Verify battery state of charge (should read approximately 12.4Vā€“12.8V at rest) and check battery terminals for corrosion or looseness, as low system voltage can trigger false driver circuit faults.
  • Scan all modules for active and stored DTCs and record freeze-frame data, noting any companion codes such as throttle body, brake switch, or PCM internal relay driver faults.
  • Locate the speed control power relay in the underhood Power Distribution Center (PDC) or Totally Integrated Power Module (TIPM), per the relay layout diagram printed on the underside of the PDC/TIPM cover, and visually inspect for burn marks, melted housing, or loose connections.
  • Inspect the cruise control (speed control) switch assembly and brake/clutch switch wiring for chafing, corrosion, or water intrusion, as a shorted brake switch circuit can mimic a driver circuit fault.
  • Check the fuse associated with the speed control circuit in the same PDC/TIPM fuse block (cross-reference the specific cavity using the vehicle’s underhood fuse diagram) for blown or loose condition.
  • Review Chrysler Technical Service Bulletins (TSBs) and NHTSA recall data for this make, model, and year, as TIPM-related driver circuit faults have documented service campaigns on several Chrysler/Dodge/Jeep platforms.

Step 2: Diagnostic Verification

  • Consult the official Chrysler wiring diagram (via TechAuthority, AllData, or Mitchell1) for the speed control power circuit and identify the exact relay cavity, connector, and PCM pin assignments for this specific VIN before testing.
  • With the relay removed and ignition in the ON (run, engine off) position, verify battery voltage is present at the relay’s control feed and switched power terminals using a digital multimeter referenced to a known good chassis ground; absence of voltage indicates an open feed circuit upstream of the relay socket.
  • With the circuit disconnected at the PCM connector, measure resistance from the relay driver output wire to chassis ground to check for a short to ground; a reading near 0 ohms confirms a short, while an open or very high resistance reading (OL) is expected in a normal, non-shorted circuit.
  • Perform a continuity check of the wiring from the relay socket output terminal to the PCM driver pin with the circuit disconnected at both ends; continuity should read low resistance (typically under 5 ohms) ā€” any open reading indicates a broken wire, corroded connector, or damaged terminal.
  • Wiggle-test the harness along its routing (engine bay, firewall grommet, and under-dash sections) while monitoring live PCM data or voltage on the multimeter to reproduce intermittent faults caused by chafed insulation or a pinched harness.
  • Confirm the PCM itself is providing the correct internal relay driver ground-side switching by checking for proper voltage drop across the circuit when commanded on with a bi-directional scan tool; a functioning driver circuit should show near-battery voltage when off and a controlled voltage drop to near 0V when the PCM grounds the circuit to energize the relay.

Step 3: Resolution & Reset Process

  • Replace the faulty relay or repair the open or shorted section of wiring using OEM-equivalent connectors, properly rated gauge wire, heat-shrink butt connectors, and weatherproof sealing consistent with Chrysler harness repair standards.
  • Replace the fuse only after confirming the cause of the overcurrent condition (typically a chafed wire shorting to ground or a failed relay coil) has been corrected, to prevent repeat fuse failure.
  • Clear all DTCs using a capable scan tool (factory-level tools such as wiTECH are preferred for full PCM/TIPM diagnostic access on later model years).
  • Perform a road test to verify cruise control engages, holds set speed accurately, resumes correctly, and cancels properly through both the brake pedal switch and (if equipped) clutch pedal switch inputs.
  • Re-scan all modules to confirm no pending or stored codes remain and that live data for the speed control driver circuit shows expected on/off switching behavior.
  • Document the repair, parts replaced, measured test values, and final road test results on the work order for warranty and quality control traceability.

šŸ“¦ Parts, Labor, and Budget Estimates

Required Components/Software:

  • Speed control power relay ā€” verify exact OEM part number against the vehicle’s VIN using a dealer parts catalog or Mopar parts lookup, as relay part numbers vary significantly by model year and platform (PDC vs. TIPM-equipped vehicles).
  • Fuse (if applicable) ā€” confirm correct amperage rating (commonly 10Aā€“20A on Chrysler speed control circuits) via the underhood fuse box legend for this specific vehicle.
  • Wiring repair kit including OEM-gauge primary wire, weatherproof heat-shrink butt connectors, and terminal pins matching the PCM and relay connector families.
  • Scan tool with bi-directional control and live PCM data capability (factory-level tools such as Chrysler wiTECH are strongly recommended for driver circuit actuation tests; aftermarket tools such as Snap-on, Autel, or Launch with enhanced Chrysler coverage are acceptable alternatives).
  • Active OEM service information subscription (Chrysler TechAuthority or equivalent) for accurate wiring diagrams, connector pinouts, and relay cavity locations specific to the VIN.

Average Component Price:

  • Speed control power relay: approximately $15ā€“$45 (OEM); aftermarket equivalents may run $10ā€“$25
  • Fuse: approximately $5ā€“$10; wiring repair materials (connectors, wire, heat-shrink, loom tape): approximately $15ā€“$40
  • Estimated total parts cost: approximately $25ā€“$95, depending on whether a full harness repair segment is required versus a simple relay/fuse replacement

Estimated Labor Hours:

  • Preliminary inspection and DTC analysis: approximately 0.3ā€“0.6 hour
  • Diagnostic verification and circuit testing (including wiring diagram cross-reference and continuity/voltage testing): approximately 0.8ā€“1.5 hours, longer if intermittent wiggle-testing is required
  • Repair, relay/fuse replacement, DTC reset, and road test verification: approximately 0.5ā€“1.2 hours
  • Total estimated labor: approximately 1.6ā€“3.3 hours, typically billed at standard shop diagnostic/labor rates of $100ā€“$170 per hour depending on region and facility type (independent shop vs. dealership)