1974 GMC MagnavanFACTORY OEM SERVICE PROCEDURE

1970 TCS System

TCS system used on 1970 General Motors vehicles is designed to regulate distributor vacuum advance. Vacuum is permitted to distributor vacuum advance unit only at cold start-up, high gear operation and in some instances, "Hot" override. System consists of a vacuum advance solenoid, idle stop solenoid, transmission switch, relay switch and a coolant temperature override switch.

Factory Service Tools

Use the Manual With the Right Hardware

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

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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.

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