1996 Lexus GS 300FACTORY OEM SERVICE PROCEDURE

Ignition Timing

NOTE: Ignition timing is not adjustable.
  1. Warm engine to normal operating temperature. Turn ignition off. Connect timing light to spark plug wire for cylinder No. 1.
  2. Remove instrument panel fuse box cover and connect scan tester to Data Link Connector (DLC) No. 3. See Fig 1. Scan tester is used to read engine RPM.
  3. Apply parking brake. Ensure all accessories are off. Place transmission Neutral. Start engine and maintain engine speed at 2500 RPM for 90 seconds and then allow engine to idle. Ensure idle speed is 650-750 RPM.
  4. Install Jumper Wire (SST 09843-18020) between terminals TE1 and E1 of DLC No. 1. See Fig 2. Connector is located near air intake chamber. Check base timing. See IGNITION TIMING  table.
  5. If base timing is correct, go to next step. If base timing is incorrect, loosen distributor hold-down bolt. Adjust base timing by rotating distributor. Tighten distributor hold-down bolt. Go to next step.
  6. Remove jumper wire from DLC No. 1. Ensure advance timing is within specification. See IGNITION TIMING  table. Remove timing light and scan tester.
Fig 1: Connecting Scan Tester To Data Link Connector (DLC) No. 3
G94C45346Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
IGNITION TIMING (Degrees BTDC @ RPM)

Application (1) Base Timing (2) Controlled Timing
Ignition Timing 10 @ 650-750 7-19 @ 650-750
(1) Jumper wire connected between terminals TE1 and E1 of DLC No. 1. See Fig 2.
(2) Jumper wire disconnected from DLC No. 1.
Fig 2: Identifying Data Link Connector (DLC) No. 1 Terminals
G93D78165Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Chapter Navigation
Return to Chapter: Engine Controls - Adjustments
Factory Service Tools

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.

Shop Manual-Ready ToolsCompare Repair QuoteQuote Shield Pro

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.