Thermo Time Switch Wire Chewed

[coreydmc]

I am having a problem starting my car. I noticed today about an inch from the connector that plugs into the TTS the wire is frayed or chewed through by a mouse. If I test the plug with my multi-meter what reading should I get to see if that is my problem? Also can I test my TTS itself by reading the ohms?

[DMCMW Dave]

I am having a problem starting my car. I noticed today about an inch from the connector that plugs into the TTS the wire is frayed or chewed through by a mouse. If I test the plug with my multi-meter what reading should I get to see if that is my problem? Also can I test my TTS itself by reading the ohms?

Yes but it's tricky. There are two connections on the plug on the TTS. It is keyed so it only goes in one way, but if the plastic is broken off the TTS it can be plugged in wrong. Plugging it in backwards will burn it out the first time you try to start the car.

One of the connections on the TTS is from the heater to ground, so you should measure some resistance to ground (sorry, I don't recall the value offhand).

The other connection is grounded (zero ohms) when the engine is cold (below 70F) and open (infinite) when warm. Measuring across the two connections doesn't really tell you anything, although when cold you'll be measuring the resistance of the heater AND proving that the switch is closed. If measuring across the leads reads infinite, something may be wrong (or it may just be warm) but you don't know what.

[coreydmc]

thanks Dave. Ill measure it later. Since the wire is broken and not making contact with TTS can this cause my car not to start in cold weather?

[DMCMW Dave]

thanks Dave. Ill measure it later. Since the wire is broken and not making contact with TTS can this cause my car not to start in cold weather?


Yes, yes it can. You are missing the cold-shot at start which is very necessary on a cold engine.

If you want to prove it, do the "plug swap" next time you cold start the car (i.e. remove the blue plug from the coldstart injector. Remove the grey plug from the warmup regulator. Start the car. Immediately remove unplug the cold start injector before you flood the engine. Put everything back where it goes.

[Ron]

Keep in mind that a grounded TTS could cause the strong smell of fuel you reported in the other thread but wire being broke wouldn't...

[Azar]

Yes but it's tricky. There are two connections on the plug on the TTS. It is keyed so it only goes in one way, but if the plastic is broken off the TTS it can be plugged in wrong. Plugging it in backwards will burn it out the first time you try to start the car.

One of the connections on the TTS is from the heater to ground, so you should measure some resistance to ground (sorry, I don't recall the value offhand).

The other connection is grounded (zero ohms) when the engine is cold (below 70F) and open (infinite) when warm. Measuring across the two connections doesn't really tell you anything, although when cold you'll be measuring the resistance of the heater AND proving that the switch is closed. If measuring across the leads reads infinite, something may be wrong (or it may just be warm) but you don't know what.
Hi Dave,

I am testing my TTS and it works as it should, except it switches to the 120 Ohm reading from zero. May this be a reason for the cold start valve running all the time and making the mixture rich? I did have problem of smelling petrol from the exhaust and everything showing that it was running rich.

BTW, your newest support article says that it opens at 35 C / 95F. mine "opens" and around 37C.
https://support.delorean.com/kb/a60/cold-start-issues.aspx