thermo time sw

[soulful66]

I want to make sure I understand how to test this switch.

cold eng...should have continunity through the switch

warm eng...no continunity through the switch

Is this correct? During Colin's last visit, we were not getting power for the thermo time switch, and had to crack the throttle and move the afm plate to get it started. The last couple of times I have started the bus, I had to depress the gas pedal to get the eng to run.

From what I understand, the Thermo time sw is closed when the eng is cold. This allows a ground to be present so the cold start valve opens to shoots extra gas for easier starting. As the eng warms up, the metal strip inside the thermo time sw opens the ground and kills the power to the cold start valve.

Best Regards,
John

[vwlover77]

Everything you said is correct.

In addition to engine heat, the thermo-time switch has an internal heating element to prevent the cold start valve from being on for too long.

According to the AFC manual, depending on engine temperature, it will allow the cold start valve to run for only 3 to 10 seconds. You don't have long to check it once you start cranking the engine!

Power is only applied to the switch while the starter is engaged.

[soulful66]

Great, thanks. I am thinking that I can test the switch with no power to see if the normally grounded metal strip is internaly disconnected.
Best Regards,
John

[Amskeptic]

Great, thanks. I am thinking that I can test the switch with no power to see if the normally grounded metal strip is internaly disconnected.
Best Regards,
John

Yes you can do a continuity test through the switch.
Remember that little red wire from the starter spade terminal (#50) to the double relay? That's our power source during cranking only.
Colin

[soulful66]

Just for future reference, the resistance through my old TTS was 33 ohms through the heating element.

The new TTS measured 35 ohms

Best Regards,
John

[Amskeptic]

Thanks for the update! We'll take it, even if it is THREE MONTHS later!
Colin