🚨 Diagnostic Profile
Vehicle Make: Dodge
Description: High Speed Fan CTRL Relay Circuit Open Or Shorted. The powertrain control module has detected an open or shorted condition in the high-speed cooling fan control relay circuit.
Model and Year: Model/Year not specified — diagnostic steps below follow generic Dodge/Chrysler PCM-controlled dual cooling fan architecture (applicable to most 3.3L/3.6L/5.7L platforms using the Totally Integrated Power Module, or TIPM). Confirm exact relay location and fuse numbering against the underhood power distribution center label for the specific model year before proceeding.
🚨 Repair Difficulty Tier
Tier: Intermediate
Relay replacement is straightforward, but circuit diagnosis requires wiring diagram access, a digital multimeter, and familiarity with PCM-controlled cooling fan circuits, as well as an understanding of how the TIPM/PCM shares fan relay control logic with the A/C and engine cooling demand inputs.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
- Verify battery voltage (should be approximately 12.4–12.6V key-off, 13.5–14.7V running) and confirm charging system output is within specification, as low voltage can cause false relay circuit faults.
- Inspect the cooling fan relay and related fuse in the underhood Totally Integrated Power Module (TIPM) or Power Distribution Center (PDC); cross-reference the fuse box lid diagram for correct cavity identification, as relay and fuse positions vary by model year.
- Check the relay socket and fan module/fan control connectors for corrosion, bent pins, looseness, or melted plastic from excessive resistance heat.
- Inspect the wiring harness along the radiator core support and fan shroud for chafing, heat damage, or rodent damage, as this is a common failure point due to harness routing near the fan blades and exhaust components.
- Record all stored DTCs and freeze frame data (RPM, coolant temperature, vehicle speed, and A/C request status at time of fault) before clearing any codes.
Step 2: Diagnostic Verification
- Confirm the fault with a scan tool capable of bi-directional controls, clear codes, then idle the vehicle with A/C on and off, and perform a road test to check for fault recurrence under varying fan demand conditions.
- With the key on engine off, use a scan tool to command the high-speed fan relay on and off while back-probing the relay control circuit; confirm the PCM pulls the control circuit to ground (typically near 0V) when commanded on, and releases to reference voltage (commonly 5V or 12V depending on circuit design) when commanded off.
- Test the relay output (switched) circuit for continuity and excessive voltage drop between the relay and the fan motor connector; voltage drop under load should not exceed approximately 0.2V per connection on a healthy circuit.
- With the relay removed from its socket, use a multimeter in resistance or diode mode to check the control circuit pin for a short to ground or a short to battery voltage; both should read open circuit (infinite resistance) unless the PCM is actively commanding the relay.
- Test fan motor current draw using an inductive amp clamp and compare against the manufacturer’s service information specification for that specific fan motor assembly; a reading significantly higher than spec indicates a binding motor or shorted winding, while no draw indicates an open circuit or seized motor.
Step 3: Resolution & Reset Process
- Repair any confirmed open or short found in the harness section between the TIPM/relay and the fan motor connector using OEM-equivalent gauge wire, heat-shrink butt connectors or solder, and weatherproof connector seals to restore original circuit integrity.
- Replace the relay only after the control and output circuits have been verified good; do not replace the relay as a first-guess fix, since a shorted downstream circuit will immediately damage a new relay or the TIPM driver circuit.
- Clear DTCs with a scan tool and verify fan operation at both low speed (A/C compressor engagement) and high speed (A/C high-side pressure or elevated coolant temperature simulation) using bi-directional controls if available.
- Run a final scan for pending or stored codes after a complete drive cycle, and document before/after readiness monitor status and freeze frame comparisons for the repair record.
📦 Parts, Labor, and Budget Estimates
Required Components/Software:
- Cooling fan relay (OEM or OEM-equivalent, typically a Bosch-style 4 or 5-pin micro relay used in Chrysler TIPM applications) — verify exact part number against VIN at a dealer parts counter or OEM parts catalog
- Wiring repair kit: OEM-gauge primary wire, weatherproof butt/splice connectors, heat-shrink tubing, and dielectric grease
- Fan motor connector pigtail or terminal repair kit if connector damage is found
- Scan tool with bi-directional control capability (OEM-level, such as a Chrysler-compatible scan tool, or a capable aftermarket tool with enhanced PCM data/actuation support)
- Digital multimeter (with min/max and inductive amp clamp capability) and access to factory wiring diagrams/service information
Average Component Price:
Cooling fan relay: approximately $15–$45 depending on OEM vs. aftermarket sourcing. Wiring repair kit/connector terminals: approximately $10–$40 depending on extent of damage. Fan motor assembly (if testing reveals it is the root cause rather than the circuit): approximately $120–$350 for the part alone, varying significantly by engine/fan configuration. Diagnostic scan tool/software access, if required through a dealer or independent shop with OEM-level software, is typically bundled into the diagnostic labor charge rather than billed separately to the customer.
Estimated Labor Hours:
Diagnostic time (circuit testing, relay/connector inspection, and verification): approximately 0.8–1.5 hours shop book time, commonly billed as a flat diagnostic fee of $100–$180 at most independent or dealer shops. Relay replacement alone: approximately 0.2–0.3 hours. Wiring harness repair: approximately 0.5–1.2 hours depending on accessibility and extent of damage. Fan motor assembly replacement, if required: approximately 0.7–1.5 hours depending on model and fan shroud configuration. Total estimated out-the-door cost for a circuit-only repair (diagnosis plus relay or minor wiring fix) typically ranges from $150–$300; if a fan motor replacement is ultimately required, total cost typically ranges from $280–$550 including parts and labor.