Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Detailed Flow
- INTERVIEW FROM THE CUSTOMER
Clarify customer complaints before inspection. First of all, perform an interview utilizing, refer to Diagnostic Work Sheet , and reproduce symptoms to understand them fully. Ask customer about his/her complaints carefully. Check symptoms by driving vehicle with customer, if necessary.
CAUTION: Customers are not professional. Never make assumptions like "maybe the customer means that...," or "maybe the customer mentioned this symptom".GO TO 2.
- CHECK SYMPTOM
Reproduce the symptom that is indicated by the customer, based on the information from the customer obtained by interview. Also check that the symptom is not caused by protection function. Refer to Fail-Safe .
CAUTION: When the symptom is caused by normal operation, fully inspect each portion and obtain the understanding of customer that the symptom is not caused by a malfunction.GO TO 3.
- CHECK VEHICLE CONDITION
CONSULT
- Ignition switch ON.
- Select "ECU temperature" in "Data Monitor" mode of "EPS/DAST 3".
Monitor item
Values
ECU temperature
90 deg. C (194 deg. F) or less
Is the inspection result normal?
YES
GO TO 4.
NO
Wait with the ignition switch OFF until the "Data Monitor" indication becomes 90 deg. C (194 deg. F) or less. Go to 4 after the temperature drops to 90 deg. C (194 deg. F) or less.
- PERFORM SELF DIAGNOSTIC RESULT
Select "Self Diagnostic Result" mode of "EPS/DAST 3".
Is any DTC detected?
YES
Record or print DTC and freeze frame data (FFD). GO TO 5.
NO
GO TO 7.
- RECHECK SYMPTOM
- Erase "Self Diagnostic Result" mode of "EPS/DAST 3".
- Perform DTC confirmation procedures for the malfunctioning system.
NOTE: If some DTCs are detected at the same time, determine the order for performing the diagnosis based on. Refer to DTC Inspection Priority Chart .Is any DTC detected?
YES
GO TO 6.
NO
Check harness and connectors based on the information obtained by interview.
- REPAIR OR REPLACE THE MALFUNCTIONING COMPONENTS.
- Repair or replace the malfunctioning components.
- Reconnect part or connector after repairing or replacing.
- When DTC is detected, erase "Self Diagnostic Result" mode of "EPS/DAST 3".
GO TO 8.
- IDENTIFY THE MALFUNCTIONING SYSTEM BY SYMPTOM DIAGNOSIS
Estimate the malfunctioning system based on symptom diagnosis and perform inspection.
Can the malfunctioning system be identified?
YES
GO TO 8.
NO
Check harness and connectors based on the information obtained by interview.
- FINAL CHECK
- Check the reference value for EPS control unit.
- Recheck the symptom and check that symptom is not reproduced on the same conditions.
Is the symptom reproduced?
YES
GO TO 3.
NO
Inspection End.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
No obligation. See pricing before you book.