Circuit Test: LS400

1998 Lexus SC 300SECTION LS400
  1. Remove starter relay from underhood junction block. Check for battery voltage at junction block relay cavity terminal No. 5. Turn ignition to START. Check for battery voltage at junction block relay cavity terminal No. 2.
  2. Turn ignition off. Check for continuity between junction block relay cavity terminal No. 1 and ground. Check for continuity between junction block relay cavity terminal No. 3 and starter terminal No. 1 (Black wire).
  3. Remove right kick panel. Using DVOM, backprobe ECM 28-pin connector E11 terminal 17 (Black wire). See Fig 1. Check for voltage with ignition in START position.
  4. Check for faulty starter relay, park/neutral position switch, or wiring harness. Repair as necessary.
Fig 1: Measuring Voltage At ECM Connector E11 (LS400)
G98A04734Courtesy of Β© TOYOTA, LICENSE AGREEMENT TMS1002
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.