NO Power TTS

[chadco]

Finally back in town and working tonight on the car. It is a 1979 911 sc Euro. I have no power to the TTS. I have checked continuity of yellow power wire from bottom of starter solenoid all the way to the TTS and it is fine. I checked for power by turning over the starter while test light connected to yellow wire and grounded to car and or engine. Nothing. I have benched tested the CSV and the AAR and TTS already and they are in spec. My WUR is out of spec and I am already in touch with Tony about that issue, but I need power to the TTS no matter what my other issue's are. Does the RED relay in the front trunk that controls the Fuel pump transfer power to the yellow wire that powers the TTS? The fuel pump is working fine and I thought maybe the relay was just not doing its job for the yellow wire but still transferring power down to the starter. Is this possible. IF that is not it, how does this yellow wire at the starter get its power. Thanks, Chad.

[boyt911sc]

Originally Posted by chadco

Finally back in town and working tonight on the car. It is a 1979 911 sc Euro. I have no power to the TTS. I have checked continuity of yellow power wire from bottom of starter solenoid all the way to the TTS and it is fine. I checked for power by turning over the starter while test light connected to yellow wire and grounded to car and or engine. Nothing. I have benched tested the CSV and the AAR and TTS already and they are in spec. My WUR is out of spec and I am already in touch with Tony about that issue, but I need power to the TTS no matter what my other issue's are. Does the RED relay in the front trunk that controls the Fuel pump transfer power to the yellow wire that powers the TTS? The fuel pump is working fine and I thought maybe the relay was just not doing its job for the yellow wire but still transferring power down to the starter. Is this possible. IF that is not it, how does this yellow wire at the starter get its power. Thanks, Chad.

Chad,

The FP relay has nothing to do with the electrical operation of the TTS. First, the yellow wire at the starter (terminal #50) gets power from the ignition switch @ START position via the 14-pin connector @ #14-1 pin. Are you able to crank or start your engine? If yes, you have power to terminal #50 (starter solenoid). Where do you test at the TTS terminals? G (small) terminal or W (big) terminal? Keep us posted.

Tony

[timmy2]

Thin Yellow wire to the TTS from the starter gets power through the extra terminal on the starter. Terminal 16.

If the connection in the starter between terminals 50 (with the thick yellow wire) and 16 is somehow bad, that could explain no power to the TTS when cranking.

You could double up the connection on 50 with a dual male tab connector to ensure the small wire gets voltage when the starter is cranking.

As Tony stated, there is nothing at the relay to affect the TTS circuit if the starter is cranking.

[stlrj]

A quick test to see if you have continuity from the yellow TTS wire to the starter solenoid is to jumper 12V to the yellow TTS wire terminal and observe the starter turn over immediately since you just energized the solenoid that pulls in the starter.

Joe

[chadco]

I am stumped! I have a good connection in the solenoid because when I jump power to the yellow wire it does engage the starter. I have continuity to the yellow wire at the TTS from the starter. SO how can I not have power to yellow wire at the TTS when I am turning the car over at the key?

[boyt911sc]

Originally Posted by chadco

I am stumped! I have a good connection in the solenoid because when I jump power to the yellow wire it does engage the starter. I have continuity to the yellow wire at the TTS from the starter. SO how can I not have power to yellow wire at the TTS when I am turning the car over at the key?

Chad,

Have you tested and checked if pin #14/1 (chassis side of the connector) gets power when you turned the ignition switch to START? If I would be doing the diagnostic test of this problem, I would connect a test light @ pin #14/1 and crank the starter. If you don't get power @ pin #14-1 during cranking there is a line problem between 14/1 pin and ignition switch. BTW, there is connector in between the ignition switch and 14/1 pin. And you have to locate it and test. Or perform a continuity test between pin #14/1 and ignition switch (yellow wire).

Are you getting power at the starter @ terminal 50 when you turned the ignition switch to start? Not sure about this, so I asked. Keep us posted.

Tony

[timmy2]

Check continuity of the red/black wire from the TTS to the CSI injector connector and same thing for the yellow wire.
Pain to get to, but it sounds like the red/black may be open.

[47silver]

[stlrj]

Originally Posted by timmy2

Check continuity of the red/black wire from the TTS to the CSI injector connector and same thing for the yellow wire.
Pain to get to, but it sounds like the red/black may be open.

Since it's such a pain to get to and assuming the CSV is connected, you might try testing the TTS for ground. It provides the ground on the second terminal for the TTS to operate. In other words, if that terminal is not grounded, no amount of voltage will make the CSV operate.

Or, you could jumper a ground on that second terminal. It should fire right up the instant you crank it.



Cheers,
Joe

[timmy2]

As stated above, grounding W should make the CSI (N17) pick up and squirt fuel when cranking the engine.
This will tell you if the switch is bad. Or if the switch below 16 on the starter isn't closing.

Here is the correct drawing of the TTS and CSI system wiring for your '79.

[chadco]

Ok, finally back in the garage. I grounded the red black wire to see if that would start it as suggested and nothing, still just turns over. I checked the continuity to the CSV from the TTS and it has continuity to the red\ black and yellow wires at the TTS on both of the connections at the CSV. So touching either side of the plug at the CSV gives continuity to the red\black and the yellow wire at the same time to the TTS. Is this correct when engine cold? I am not sure what is meant when saying check power to 14\1. Does that mean to both terminal 14 and 1 when starting? I have power at 14 all the time with key off or on and I have NO POWER to pin #1 with the key off or in Start position. I do have continuity from pin 14 to pin 1.

[timmy2]

14/1 would mean pin one on the 14 pin connector.
If your starter spins you have to have power at pin one when cranking.

[timmy2]

I am confused after re-reading your last post. You say you have no power to pin 1 of the 14 pin connector when the key is in the start position. But earlier you said you can crank the starter.
Are you checking pin one with the 14 pin connector disconnected on the female plug? That would be correct, there should be no power to pin one of the female engine harness connector with the engine harness plug disconnected.
You need to check the male pin 1 on the rear fuse panel when key is in Start position and the 14 pin plug to the engine disconnected..

Here is how the circuit and power flow works from front to back of the car: (If you have the '78 current flow diagram to follow, it goes from top to bottom)

The yellow wire gets power from the ignition switch contacts when in the start position only, then it runs through the chassis harness to the rear fuse panel to pin 1 on the male 14 pin connector.
Then it goes through the female 14 pin connector into the engine harness directly to the starter solenoid (terminal 50).

When the Starter solenoid engages as you turn the switch to start, a set of contacts in the solenoid close allowing the starting solenoid power to travel from terminal 50 to Terminal 16 on the starter (to the thinner yellow wire).

The thinner yellow wire goes directly from the solenoid terminal 16 to one side of the Cold Start Injector (CSI) connector and doubles back from there directly to the TTS terminal G to start warming the switch resistor so the injector cuts out on over cranking by opening the path to ground for the red black wire....

If the TTS is closed due to cold temperature, then the red black wire provides a path back to ground allowing the CSI solenoid to pull in and let fuel spray.
If the TTS is shorted internally or open then the CSI solenoid won't pull in and spray fuel. (Shorted would mean the CSI solenoid sees 12v on both sides and won't pull in)
(open means there is no path to ground for the red/black wire)

Things to try:

Removing the red black wire from the TTS terminal and grounding it with a jumper to the engine case and then cranking the starter should make the CSI spray fuel. Do you have a pop off valve and an original air box? If so, you can possibly see or even hear the fuel being sprayed out the CSI by looking in while cranking. (Distributor cap off, or plugs pulled as you don't want a spark to blow back up through the pop off while looking in there!)

My other thought is the switch in the starter may not be working, so put both yellow wires at the starter on terminal 50 and see if it works. (Mentioned this test a few posts ago)

[chadco]

Timmy2 you are correct, the pin # 1 does have power when in start position. I was testing the female side. I tried grounding the red\black side of the TTS and it did not do anything. I have bench tested the TTS and the CSV and the AAR and all are working properly. I tested power to the yellow wires at the solenoid during cranking and both are getting power when key is ignited. Still no power signal to the yellow wire at the TTS. If I jump power from 12v source to the TTS yellow and spin over the starter then it will instantly try and fire off. I then disconnect the external power source and turn over the starter again and it will run. I am somehow not getting the power signal from the solenoid to the TTS. The thing I can't understand is If I use the continuity meter I get a good signal from the yellow at the starter to the TTS? When you mentioned pulling both yellow wires on terminal 50 what does that mean? I think the switch in the starter is working because I am getting power signal when key is cranking on both yellows at the solenoid. I think I understand the path now that you have explained it in detail, I just can't figure out how a wire can have continuity and still not travel the power to it's source.

[timmy2]

Ok, I am going to have to ask.
You didn't happen to accidentally swap the air flow switch connector and the cold start injector connector at the back of the CIS system did you?

[timmy2]

I didn't say pull the yellow wires, I said place them both on 50. But if both have power when cranking don't bother.

[boyt911sc]

Chad,

PM you with my tel.# and Dennis'.

Tony

[timmy2]

Happy to talk on the phone with you Chad.