1969 Jeep Commando 3.7L EngFACTORY OEM SERVICE PROCEDURE

Transmission Controlled Spark: Maintenance

Periodic maintenance of Transmission Controlled Spark components is not normally required, should a switch or valve fail to operate properly it should be replaced. However the following components do require maintenance or adjustment to keep exhaust emission system as a whole, working properly.

Component Service Interval (Miles)
Oil Filler Cap Clean Every 6, 000
Exhaust Heat Valve Lubricate Every 6, 000
Drive Belts Adjust Every 6, 000
Air Cleaner Clean Every 6, 000
  Replace Every 12, 000
Distributor Cam Wick Rotate Every 6, 000
  Replace Every 12, 000
Oil Filler Cap Clean Every 6, 000
PCV Valve Replace Every 12, 000
PCV Filter (6 Cyl.) Clean Every 12, 000
Charcoal Canister Inlet Filter
  (V8 Auto. Trans. Only) Replace Every 12, 000
Carburetor Adjust Every 12, 000
Spark Plugs Clean Every 12, 000
Ignition Timing Check Every 12, 000
JEEP EMISSION CONTROLLED DISTRIBUTOR VACUUM APPLICATION

MANUAL TRANSMISSION (GEAR) AUTOMATIC TRANSMISSION (VEHICLE SPEED) AMBIENT (AIR) TEMPERATURE COOLANT TEMPERATURE VACUUM APPLIED TO DISTRIBUTOR
3 SPEED 4 SPEED
1-2 1-2-3 Under 25 MPH Below 63°F Below 160°F Manifold
1-2 1-2-3 Under 25 MPH Below 63°F Above 160°F Ported
1-2 1-2-3 Under 25 MPH Above 63°F Above 160°F None
1-2 1-2-3 Under 25 MPH Above 63°F Below 160°F Manifold
3 4 25-30 MPH Below 63°F Below 160°F Manifold
3 4 25-30 MPH Below 63°F Above 160°F Ported
3 4 25-30 MPH Above 63°F Above 160°F Ported
3 4 25-30 MPH Above 63°F Below 160°F Manifold
NOTE: If equipped with thermal vacuum switch (TVS), intake manifold vacuum is applied to the distributor when engine coolant temperature reaches 225°F.
Factory Service Tools

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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.

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