Why Only 6 Volts to the Cold Start Valve?

[Vincent Hill]

I have a 1982 Porsche 911sc about 140,000 miles. cold (that is only Florida Cold 50 to 70 degrees) it starts hard by taking a lot of Revolutions and Sputters to life and Runs Excellent the Rest of the day!

I finally got tired of this and first thought “Bad Cell” in the Battery (low Voltage while Cranking). Replaced the Battery.

Finally I Dug in to see what the problem was. The Car warmed up Great so not the Warmup Regulator.

So tested the “Thermal Time Switch and it flows Current 100% for a Few Seconds so it seems to be OK.

THEN the Cold Start Valve. First thing in the Morning with a good Ground and the Probe in the Yellow wire side I see 6 Volts. I test the Continuity of the Thermal Time Switch yellow wire to the Cold Start Valve and 0 Resistance. I check the Red Black wire side and 0 Resistance.

I Replaced the Red Circuit Relay and No Difference.

My question is how do I get 12 Volts to the Cold Start Valve? Do I Need to Replace the Solenoid/ Starter??

[timmy2]

What is your voltage at the starter on your yellow wire when cranking?
The TTS and the CSV will only see what is available at that time.

[Vincent Hill]

Originally Posted by timmy2

What is your voltage at the starter on your yellow wire when cranking?
The TTS and the CSV will only see what is available at that time.

Excellent Question! I also will Know Tomorrow! Already have it up on my Ramp and after checking EVERYTHING that was left and hoping the answer was elsewhere, because if it is There, then it means the Starter if reads the same, but my Hope is a bad Wire. Will let you know!

[Walter_Middie]

Vincent,

Just a word of caution that has tripped up many people:

I test the Continuity of the Thermal Time Switch yellow wire to the Cold Start Valve and 0 Resistance.

A wire can show no resistance, but still may not be able to carry enough current to light a light bulb. For example, a wire that needs to carry a lot of current is thicker, but both a thin wire and a thick wire will both show 0 resistance. If you have a wire with say 12 strands, and only one strand of the wire is still connected or not broken, it will still show 0 resistance, but when you try and light a light bulb with 12 V, you only get 2 or 3 volts at the bulb, and it barely comes on.

If you are getting 6 volts, you have a connection - just a bad connection. Dirty contacts or a partially broken wire. Clean your contacts - that's the most likely problem. Don't skip cleaning the contact if they "look" good from the outside. The corrosion happens between the contacts, not always on the outside.

Best of luck.

[Vincent Hill]

Originally Posted by Walter_Middie

Vincent,

Just a word of caution that has tripped up many people:



A wire can show no resistance, but still may not be able to carry enough current to light a light bulb. For example, a wire that needs to carry a lot of current is thicker, but both a thin wire and a thick wire will both show 0 resistance. If you have a wire with say 12 strands, and only one strand of the wire is still connected or not broken, it will still show 0 resistance, but when you try and light a light bulb with 12 V, you only get 2 or 3 volts at the bulb, and it barely comes on.

If you are getting 6 volts, you have a connection - just a bad connection. Dirty contacts or a partially broken wire. Clean your contacts - that's the most likely problem. Don't skip cleaning the contact if they "look" good from the outside. The corrosion happens between the contacts, not always on the outside.

Best of luck.

100% thank You!! Excellent thinking all around! Believe it or not, today when I checked the Voltage, I had ZERO Plans of removing and cleaning THR Contacts. What makes me mad at myself is, I have all kinds of Small to large Stainless Brushes for cleaning the Tail lights but for some reason never a thought in that Direction!!

So I will test as is, Then clean everything and I have Several Test lights and a nice 12 Volt Motorcycle Battery to use for Current flow.

You have added a Lot to my “Plate” but all is appreciated!! KISS is at work again (Keep it Simple Stupid)

[Vincent Hill]

Well the Rain went away and had a nice day in the Mid 70’s

With an engine that has not been started in Several Days, attached the Black Probe on my voltage Meter to the Engine Ground strap and slid up the Yellow wire Connector a little and with the Red Probe on the Copper terminal 15a had my wife turn over the engine for 5 seconds! [I got ZERO VOLTS!!! I guess the Solenoid on the Starter is bad! The picture shows the Terminal I tested with a Green Line pointing to it!

[Vincent Hill]

Originally Posted by Vincent Hill

Well the Rain went away and had a nice day in the Mid 70’s

With an engine that has not been started in Several Days, attached the Black Probe on my voltage Meter to the Engine Ground strap and slid up the Yellow wire Connector a little and with the Red Probe on the Copper terminal 15a had my wife turn over the engine for 5 seconds! [I got ZERO VOLTS!!! I guess the Solenoid on the Starter is bad! The picture shows the Terminal I tested with a Green Line pointing to it!

I “MAY” know what the problem is! Many years ago, I was working on the Steering shaft, I had the Ignition Switch out and it “Came Apart!” I got EVERY PICTURE POSSIBLE and my bet is I got the wire that charges the Cold start valve WRONG!!

[timmy2]

If the starter was cranking, the ignition switch wiring is fine.
Possibly the built in starter contacts have failed.
Connect the thin yellow/blue wire to the fatter yellow wire on terminal 50 and your TTS will get power to it whenever you crank the engine.

[timmy2]

Thin blue yellow to 16, fat yellow to 50.
Contacts supposed to close when solenoid is energized.

[Vincent Hill]

Originally Posted by timmy2

Thin blue yellow to 16, fat yellow to 50.
Contacts supposed to close when solenoid is energized.

THANK YOU!! I hated the idea of dealing with that switch again and wondered if I could take power from somewhere else.

I see we ALMOST totally agree on Exhaust system. I put a 3” round baffle that I split and knocked into a he Pipe outlets so No Droaning inside

[Vincent Hill]

To Timmy, Walter and Everyone that helped me Thank you. Using the terminal from the starter made it start instantly