NOTE: Data Link Connector (DLC) No. 1 is located:

Ensure engine is at normal operating temperature. Connect timing light magnetic pick-up to spark plug wire for cylinder No. 1. Connect tachometer test lead to terminal IG- of DLC No. 1, located on front end of air intake chamber. See Fig 1. Connect jumper wire between terminals TE1 and E1 of DLC No. 1.
Ensure idle speed is within specification. See IDLE SPEED SPECIFICATIONS table under IDLE SPEED & MIXTURE. Check base timing. See IGNITION TIMING table. If base timing is within specification, go to next step. If base timing is not within specification, adjust timing by rotating distributor, then go to next step.
Disconnect jumper wire from DLC No. 1. Check controlled timing. See IGNITION TIMING table. Ensure controlled timing is within specification. If controlled timing is not within specification, problem exists in engine control system.

IGNITION TIMING (Degrees BTDC @ RPM)

Application

Base ⁽¹⁾

Controlled ⁽²⁾

SC300

10 @ 650-750

7-19 @ 650-750

⁽¹⁾	Jumper wire connected between terminals TE1 and E1 of DLC No. 1. See Fig 1.

⁽²⁾	Jumper wire disconnected from DLC.

Fig 1: Terminal Of Data Link Connector ID (DLC) No. 1

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.

Safety Warning

Data Link Connector (DLC) No. 1