Dennis Wilson

Jeff,

Looking at the diagram you will notice half of the heating element wiring (4) will always go to ground but it is too small to power the cold start valve. That's why Haynes recommends a live test in para 16. In the diagram, the left contact is wired to the cold start valve which is powered by the starter (circuit 50). The fuel pump relay mentioned in para 17 is for the AAV.

Dennis

Dwayne

Hello Jeff,
I feel your frustration because I went through the same thing last fall when I was testing my TTS as well. I got the exact same results you did. "W" terminal tested at 0 ohms when cold according to spec while the "G" terminal showed 35.7 ohms when cold - spec was supposed to show 0 ohms on "G" according to the manual.

So, thinking I had a defective TTS, I ordered a new one. Installed it and guess what.....same results!! I didn't know what to make of it (maybe an error in the manual??) but I left the new one in and moved on to look at other problems. This work was on the '84 so should have the same parts and set up as yours. I've been driving it with the new one and with the "out of spec" G terminal and it doesn't seem to have any effect. Let me know if you solve this mystery! Good Luck.

Landseer

Guys,

Where is the TTS located? Is it near other sensors?

jpitman2

Its similar in appearance to item 2 here:- http://members.rennlist.com/v1uhoh/underthe.htm , but on a 16V its horizontal into the water bridge IIRC. Should have a temp and a time (secs) stamped on it , as in "65C 8" or similar.
jp 83 Euro S AT 51k

Optimator

Jeff,

Regarding the TTS: The test figures in the factory WSM are wrong. Have a look at this thread - in particular posts 48, 58, 64, 67 and 68:

https://rennlist.com/forums/showthre...=354242&page=4

I have not put a great deal of thought into your problem, but have you bypassed the CSV with a test light yet (as described in the manual page that Dennis posted)? It's possible that even though your TTS is testing OK at ambient temperature, it may be malfunctioning when current is applied. For example, it may be opening the circuit way too fast. It's supposed to keep the CSV open for 8-10 seconds under most conditions. If the TTS is closing the CSV after only 1 second, for example, then that would explain your observations.

jwarner6

Thank you so much for the confirmation. I'm now sure the manual is wrong and I think the reason why is the size of the wires on the G pin. My quess right now as to what is happening is that the TTS is shutting off too quickly due to ambient temperature and the heating of the G curcuit. I'm going to bench test a TTS to see how quickly it shuts off the connetion on the W side. This would explain why I would normally get one or two starts and then no more. I'll post my results when I have them. Thanks.

jwarner6

Thank you too. The CSV should only fire as long as the starter circuit is engaged and provided the W circuit is still closed. I believe mine is opening too quickly. I read those posts imediately!

jwarner6

Okay here are the test results. Some interesting observations and concurance with the posts mentioned earlier. The service manual is wrong for the G pin. Minimum readings at the G pin will be at least 34ohms and won't really change with temperature. The G pin simply heats up the W circuit causing it to open after a few seconds (the CSV stops injecting) if it isn't already open due to coolant temperature. What I found, consistently, at least with old switches, is that the closed contact time of the W circuit, once power is applied to the G circuit, is very short on anything but a very cold switch and you have to allow some time for the switch to recover first if you want more juice on your next turn of the key!

I set up a simple test rig to test the funtion of the switch.

- 12 volt power source (i just used a car battery).
- TTS body connected to battery negative post.
- Connected a spare switch connecter to the switch.
- Connected the W lead of the connecter to a 12v test light (I used a twist in dash bulb).
- Connected the other side of the test light to the positive side of the battery. This will make the light come on unless the switch is already too warm (above 86f). The test light will represent the CSV getting juice to squirt.
- Connect another test lead to the G circuit lead. Touching this test lead to the positive post will simulate the starting cuircuit supplying power to the TTS for a potential cold start. Don't touch it to the positive post until you're ready for the test or your test maybe over before you know it.

First ambient air test (84f) of switch out of car.

- Bulb was not very bright. Checked the voltage between the positive post and the switch body and it was already only 5 volts so the CSV probably would not be used when the car was started. So the switch was most likely already too warm. Touched the G lead to the battery postive post and the light went out immediately. Take it off and the bulb goes back to dim. So the G circuit immediately heated the W circuit enough to open the circuit completely. Could repeat over and over again.

Second ambient air test (72f) of switch out of car.

- Took the two spare switches into the house to let them cool down for an hour or so. Now when hooked up to the rig the bulb is nice and bright and a full 12v. Touch the G circuit to positve post and bulb stayed lit for 5 seconds then went out (CSV stops squirting). Removed G circuit and bulb went dim. Bulb stayed dim for about 12-15 seconds (cooling) then went bright again (W circuit closed again as it cool off). Connected G circuit again and bulb lit for only 2 seconds. Another 12-15 seconds was required for the W circuit to reestablish itself (bulb bright) and then I could repeat again but once again for only 2 seconds. If I just removed the G circuit and then restablished it, the bulb would just go from dim to off. In other words. I would have not gotten a shot for the CSV if I immediately tried starting the car again and even if I wait for say 20 seconds for the W circuit to close I would still get only 2 seconds out of the CSV on the next and subsequent tries. Repeated with the other switch and got the same results. A good first squirt and short subsequent squirts but only after waiting 12 to 15 seconds between attempts.


Third test with frozen switches out of car.

- Froze the two spares for an hour. Hooked up the first one and got a nice bright bulb as expected. Touched the G curcuit to the battery and got 8 seconds before the light went out. With the G circuit removed, the bulb went bright again after 5-7 seconds. Touched the G circuit again and got about 4-5 seconds this time. Recovery between successful attempts was quicker then at 72f but it didn't take long to get down to only 2 seconds again for each squirt. So with a really cold car you would have gotten 2 or 3 decent squirts but you won't get that second or third squirt or any others for that matter unless you wait a while (5-7 seconds) betweens attempts.

So to summarize, according to my results:

- If your car is even warm (near 86f) the CSV will not fire.
- If your car is just normally cold (say between 50f and 70f) you'll get one long shot if you need it and short ones after that but only if you wait at least 15 seconds between attempts.
- If it's Winter, you'll get more juice on more attempts but you still have to wait a little while between attempts if you've broken the W circuit.

It would be nice to do this test on a new TTS to see if it recovers quicker. But this behaviour may be correct and as expected.

Enjoy.

Jeff

jpitman2

Great test, well done. The dim bulb may indicate burnt contacts in the unit, shortening the effective CSV squirt. If the new units did the same, that shouldnt be the issue. I just went through this with a warm start sensor on my K-jet car - when it was supposed to fire a solenoid it still showed a resistance of 25 Ohms, enough to prevent solenoid firing. New sensor fixed the problem.
jp 83 Euro S AT 51k

honerboys

so it seems the manual is wrong on the measurements for the thermo time switch - hmmm - i guess mine is ok then...???