Diagnose check engine light (MIL) on a 2022 Rivian EDV 500 dual motor electric delivery van using OBD-II diagnostic tools to identify fault codes and system malfunctions.

Warnings

Tools required

Parts

• 12V auxiliary battery × 1 — Use OEM specification

Preparation

1. Ensure vehicle is parked on level ground with parking brake engaged
2. Verify 12V auxiliary battery is fully charged (minimum 12.4V at rest)
3. Ensure diagnostic scanner is updated with latest Rivian software definitions
4. Have vehicle VIN available for diagnostic software
5. Document any customer concerns or driving conditions when MIL illuminated
6. Note any other warning lights or messages on instrument cluster

Procedure

1. 1

   Initial System Check
   Perform visual inspection of instrument cluster. Note all warning lights, messages, and indicator status. Check for obvious issues like loose gas cap (if equipped), damaged wiring harness, or fluid leaks. Record current odometer reading and any observable vehicle behavior anomalies.
2. 2

   Verify 12V Auxiliary Battery Condition
   Test 12V auxiliary battery voltage with multimeter. Should read 12.4-12.8V with vehicle off, 13.8-14.4V with vehicle in ready mode. Low voltage can cause multiple false codes. If voltage is low, charge or replace battery before proceeding with diagnosis.
3. 3

   Connect Diagnostic Scanner
   Locate OBD-II port beneath driver side dashboard. Connect diagnostic scanner ensuring secure connection. Turn vehicle to ON/READY mode without energizing drive system. Wait for scanner to establish communication with all vehicle control modules (typically 8-12 modules on EDV 500).
4. 4

   Retrieve Diagnostic Trouble Codes
   Perform complete vehicle scan to retrieve all stored DTCs (Diagnostic Trouble Codes) from all modules including Battery Management System, Motor Control Units (front and rear), HVAC controller, ABS/ESC, and body control modules. Record all codes with freeze frame data including: code number, description, status (current/pending/history), occurrence count, and environmental conditions when set.
5. 5

   Analyze Fault Code Priority
   Identify primary fault codes versus secondary/related codes. On electric vehicles, prioritize in this order: 1) High voltage isolation faults, 2) Battery management system codes, 3) Motor controller codes, 4) Charging system codes, 5) Auxiliary system codes. Cross-reference codes with Rivian TSBs (Technical Service Bulletins) for known issues.
6. 6

   Check High Voltage System Status
   Using diagnostic scanner, check high voltage battery pack parameters: state of charge, cell voltage balance, isolation resistance, coolant temperature, and any battery fault flags. Verify both motor controller units show normal operating parameters. Do not physically access high voltage components at this stage.
7. 7

   Inspect Related Components
   Based on retrieved fault codes, perform targeted visual inspection of related components. For motor codes: check motor connections and coolant lines. For battery codes: inspect battery pack enclosure for damage. For sensor codes: inspect specific sensor wiring and connectors. Look for corrosion, damaged pins, or disconnected harnesses.
8. 8

   Perform Circuit Testing
   If codes indicate sensor or circuit faults, use multimeter to test affected circuits. Verify sensor supply voltage (typically 5V or 12V), ground continuity, and signal voltage within specification. Check for short circuits to ground or power. Test connector resistance and inspect for moisture intrusion.
9. 9

   Review Live Data Stream
   Monitor live data parameters using diagnostic scanner while vehicle is in ready mode. Compare actual values to expected specifications for: coolant temperatures, motor resolver signals, battery current flow, DC-DC converter output, brake system pressure, and vehicle speed sensors. Look for erratic or out-of-range readings.
10. 10

    Clear Codes and Road Test
    If no hard faults are found and repairs have been made, clear diagnostic codes from all modules. Perform road test under conditions that originally triggered the MIL if known. Monitor for code recurrence using scanner in real-time mode. Test should include: acceleration, deceleration/regenerative braking, turning, and highway speed operation for at least 15 minutes.
11. 11

    Re-Scan and Document Findings
    After road test, perform complete vehicle scan again to check if codes have returned. Document final results including: codes found, root cause analysis, repairs performed, parts replaced, and verification test results. If codes return immediately, further diagnosis of specific system is required.

Reassembly

1. Ensure all connectors inspected during diagnosis are properly secured and locked
2. Verify diagnostic scanner is disconnected and OBD-II port cover is reinstalled
3. Confirm all access panels or covers removed during inspection are properly reinstalled
4. Reset vehicle infotainment system if diagnostic procedures required battery disconnect

Verification

• Confirm MIL (check engine light) is extinguished after clearing codes
• Verify no pending or current fault codes remain in any control module
• Test drive vehicle minimum 15 minutes to ensure codes do not return
• Confirm all vehicle systems operate normally including regenerative braking, climate control, and power delivery
• Verify 12V auxiliary battery voltage remains stable in ready mode (13.8-14.4V)
• Document all diagnostic findings and provide customer with explanation of root cause and repairs performed

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