Hot Engine Test

Disconnect vacuum hose No. 2 from vacuum advance diaphragm B. Connect vacuum gauge to hose. Connect tachometer. Start engine and run at idle. Check for vacuum at vacuum hose No. 2. If there is no vacuum, proceed to step 5).
If there is vacuum, check the following: On all models except Fed. 1500 HF, replace thermovalve B and retest. On Fed. 1500 HF models, check for voltage between cold advance solenoid valve terminals (Red/White wires at control box No. 1 connectors).
If there is no voltage, replace cold advance solenoid valve and retest. If there is voltage check speed sensor and thermosensor B. Check for voltage at control unit connector (Blue wire) with ignition on. There should be voltage. If no voltage, check Blue wire between ignition coil and control unit.
Check for voltage at control unit connector (Black/Yellow wire) with ignition on. There should be voltage. If no voltage, check fuse and wiring. Ensure Black wire between control unit and ground has continuity.
Attach a hand vacuum pump to both vacuum advance diaphragms using a "T" fitting. Plug vacuum advance hoses. Pinch off hose to vacuum diaphragm B. Start engine and apply 16 in. Hg vacuum. Ensure timing advances and vacuum remains steady. If not, replace advance diaphragm and retest.
If timing did not advance, check breaker plate for freedom of movement. Repair or replace as necessary. If breaker plate moves freely, replace vacuum advance and retest.
Released pinched vacuum hose and apply 16 in. Hg vacuum. Timing should advance more than in step 5) and remain steady. If timing advances more than in step 5), system is okay. If timing does not advance more than in step 5) or will not stay advanced, replace vacuum advance and retest.