How to Fix Diagnostic Code P1765

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šŸšØ Diagnostic Profile

Vehicle Make: Chrysler

Description: Transmission 12 Volt Supply Relay Control Circuit Open or Shorted. The transmission control module (TCM) supply relay control circuit has reported an open or short-to-ground/voltage condition.

Vehicle Application: Chrysler/Dodge/Jeep platforms utilizing a TCM-controlled transmission relay (e.g., 41TE/62TE, 545RFE, or NAG1 equipped vehicles); exact fuse/relay box layout varies by model year and platform, so confirm configuration using the specific VIN-matched service manual.

Relay Location: Typically located in the Totally Integrated Power Module (TIPM) or underhood Power Distribution Center (PDC), depending on model year and platform. Confirm exact relay cavity position using the label on the underside of the PDC/TIPM cover or the VIN-specific service manual.

šŸšØ Repair Difficulty Tier

Tier: Intermediate

Rationale: Diagnosis requires multimeter testing of relay control and supply circuits, wiring continuity checks, and scan tool access to transmission module data. Repair is typically a relay replacement or wiring repair, but a wiring fault may require connector and harness work.

šŸ› ļø Resolution Steps

Step 1: Preliminary Inspection

  • Verify battery state of charge (minimum 12.4V at rest) and confirm charging system output is within normal alternator range (typically 13.5Vā€“14.7V) using a digital multimeter at the battery terminals with the engine running.
  • Inspect the PDC/TIPM relay box and fuse panel for corrosion, loose terminals, melted plastic, or water intrusion, which are common causes of intermittent relay control faults on these platforms.
  • Visually inspect the transmission control module connector and harness for chafing, pin damage, pushed-back terminals, or contamination, paying close attention to areas near the engine/transmission mounts where flexing occurs.
  • Check the fuse associated with the transmission supply circuit located in the PDC/TIPM; confirm fuse amperage rating matches the label on the PDC cover before replacement.
  • Record and clear all active and stored diagnostic trouble codes before testing, and note any freeze frame data or associated codes (such as charging system or PCM communication faults) that may indicate a shared root cause.

Step 2: Diagnostic Verification

  • Use a scan tool capable of bidirectional control (such as a factory-level or enhanced aftermarket scan tool with Chrysler coverage) to confirm the fault status and view live data for the relay control circuit, including TCM-commanded relay state versus actual circuit voltage.
  • Measure supply voltage at the relay socket with the key on, engine off; confirm battery-reference voltage is present on the constant power pin per the relay socket pinout for that model.
  • With the relay removed, measure the control circuit for proper ground or open-circuit behavior commanded by the TCM; an open circuit should read near-infinite resistance, while a short-to-ground will read near 0 ohms to chassis ground.
  • Check the control circuit for short to ground and short to voltage by back-probing the relay connector control pin and measuring voltage against a verified clean chassis ground, referencing the appropriate wiring diagram for that specific VIN and transmission application.
  • Perform a relay swap test with a known-good relay of the same part number and type, if available, to isolate a faulty relay from a wiring or TCM driver fault.
  • Check all transmission and TCM-related ground connections for corrosion and resistance within an acceptable range (typically under 0.2 ohms) using a digital multimeter in continuity/resistance mode.

Step 3: Resolution & Reset Process

  • Replace the faulty relay or repair the open or shorted wiring section using standard industry wire-repair practices (solder and heat-shrink or approved crimp connectors rated for automotive underhood use), following the OEM service manual repair procedure for that circuit.
  • Restore any damaged connector pins and verify secure seating and locking tabs at both the TCM and relay box connectors.
  • Reconnect the battery and clear diagnostic trouble codes with a scan tool; verify no immediate code resets occur with key-on engine-off and key-on engine-running tests.
  • Perform a road test or scan-tool-guided transmission drive cycle to confirm the fault does not return and that shift quality, torque converter clutch operation, and line pressure control are functioning normally.
  • Recheck for stored or pending codes after the drive cycle, confirm live data for relay control circuit status remains consistent with commanded state, and document the final test results including before/after voltage readings.

šŸ“¦ Parts, Labor, and Budget Estimates

Required Components/Software:

  • Transmission supply relay: OEM Chrysler relay (standard ISO Micro 280/Bosch-style relay, typically interchangeable part across several Chrysler platforms ā€” confirm exact OEM part number using VIN lookup)
  • Wiring repair kit or harness section, if required: OEM-grade automotive wire repair kit with weatherproof connectors and heat-shrink butt splices rated for underhood use
  • Replacement fuse, if required: OEM-specified mini or maxi fuse matching PDC label amperage rating
  • Scan tool with transmission module access: Factory-level diagnostic software (such as a current subscription to a Chrysler-compatible diagnostic platform) or enhanced aftermarket scan tool with bidirectional TCM control and live data capability

Average Component Price:

  • Relay: $15ā€“$45 (OEM); $8ā€“$20 (quality aftermarket)
  • Wiring and connector materials: $20ā€“$75 depending on harness section length and connector complexity
  • Fuse: $5ā€“$15
  • Diagnostic software/subscription (if required for dealer-level programming or verification): $30ā€“$150 per day/session for aftermarket platforms; dealer diagnostic fees typically $150ā€“$250 flat

Estimated Labor Hours:

  • Diagnosis and verification: 1.0ā€“2.0 hours
  • Relay or wiring repair: 0.5ā€“2.5 hours (relay swap is quick; harness repair near TCM or PDC can extend time significantly depending on accessibility)
  • Verification and drive cycle: 0.5ā€“1.0 hours
  • Total estimated shop labor: 2.0ā€“5.5 hours at prevailing shop labor rate (commonly $100ā€“$180/hour depending on region and shop type)