Barry's70LT1

I had the exact same problem as you. Mine is original T.I. with upgraded solid state amplifier. I resolved the problem. Now you barely hear the starter kick in and it starts immediately. Before the fix you could crank all day without a kick, then if you were lucky, it would start when you released the key.

The fix (Or work around)
About 8 years ago the TI ignition failed, left me on the road about 60 miles from home.
The failure was the pickup coil in the distributor.
I purchased a new pickup, and, since the TI amp was original, I replaced the circuit card with a new solid state circuit card.

Everything worked great for a couple of years. Then it got harder and harder to start, only starting when key was released.

Long story short, after much testing, It would start great with the starter solenoid wire DISCONNECTED, and the ign wire to the amp connected directly to 12V.

For the past few years I have had a relay connected from Horn relay (12V) to the white wire from the amp (originally connected to 12V key supply)
12V key ign supply wire now powers the relay. Starter solenoid wire remains disconnected.

As long as it keeps working great, I won't be chasing it any further.
I suspect the solid state module is causing the ignition not to work correctly with the starter wire connected.

69 Coupster

Ok that’s exactly what’s going on here I’m pretty sure. I recall that the local guru had to fix a broken wire in the pick up coil before it world work properly. Maybe that repair has failed or something else in there has. Im not sure I’m ready to do a work around wiring fix right now. Would prefer to keep her original if possible. Are new pickup coils still available in the market anyplace?

Big2Bird

Yes.

Rescue Rogers

To test hook a probe to th plus side of the coil and to with the key in run. It will have 12 volts, you already have that. Then turn the key and see if it drops below 10 volts it shouldn’t drop much but will due to the starter cranking...if it goes to zero, you have a better place to look

Barry's70LT1

If your pickup coil is bad, then it would never start. Per your description you're not getting any spark while cranking, problem is not likely the pickup.

To test a theory, disconnect the wire from the starter to the TI harness. That plug is very near the the pickup plug, single wire connector. If that does not change the starting condition, then temporarily connect a wire from the horn relay (12V) to the power wire going to the amp.
If it starts and runs well, then you have the same problem I have.
At that point I don't know what you do to fix it, other than replacing parts.

I know you want to keep it original, and I share that desire. When I added the relay to mine, no existing wires were cut or spliced or removed. I installed the relay under the wiring harness, near the distributor, not visible.

Keep us updated on your progress.

69 Coupster

Ok I checked and have a constant 12volts at the positive terminal on the coil. Makes no difference when cranking or not. The needle on my voltmeter stays at 12 volts.

what if my two wires on the starter solenoid are reversed? Not the battery cable but the R terminal and the S terminals. both are white color. I’m going to check continuity next to determine which is which.

69 Coupster

. Well that didn’t work. Can’t get any continuity reading from the white resister wire at the coil down to the starter. Looks like it leaves the coil and goes forward in the bundle up to the transistor box.

looking a the solenoid, the larger white resister wire is hooked up to the S terminal. The other wire could be yellow, it’s hard to tell, and it’s on the R terminal. I’m not going to try it by switching them until I get more advise from you or someone on this from this forum.. Thanks again. all this help is really appreciated. 👍

ClothSeats

As I stated in my earlier post, you should have pulses at the + terminal of the coil that alternate from zero volts to +12 volts when cranking. Since you read a steady +12 volts at the + terminal of the coil while cranking, that leads me to believe that you have a defective ignition module. You stated in the OP that it won't fire until you release the key, so if that means you get one fire and then dies, that supports the thinking of a bad ignition module. You currently have a steady +12 volts on the ignition coil while cranking, which won't create spark because you need pulses, but when you release the key, that +12 volts on the coil goes away, resulting in collapse of the magnetic field in the coil, which will give only one ignition spark, and then nothing.

Barry's70LT1

If the wires were reversed at the starter, then the starter would not work. One wire energizes the starter solenoid, when cranking. This action then energizes the second wire with 12V that is fed back up to the ignition.

The 12V from the starter does NOT go to the + side of the coil. (As in a point system) It goes to the Amplifier thru one side of the pickup coil. Mine would not start while cranking if that wire was connected. It makes no sense.

As I mentioned before, that wire from the starter is connected near the distributor, to a wire that is connected to the pickup plug.
If you wanted to check if you were getting 12V there, disconnect the wire and check if you are getting 12V at the wire while cranking. Should be "0" volts without cranking. (While disconnected from the harness)

Maybe first check to see if even that wire is connected to the harness. Easy plug to forget as it leaves the TI harness and heads to the passenger side down to the starter.

69 Coupster

Well, it seems to have resolved itself. I have disconnected or unplugged wires to checked voltages and followed all suggestions here. I did have 12v at the starter R terminal both in the on and in cranking positions. Also had 12v at the one white wire connecting to the pink wire from the dash. I didn’t change a thing and I put it all back as it was but now she’s firing up right away in the cranking position. I’m not thrilled that I couldn’t find the exact cause because it’ll probably happen again. Time will tell I guess. Thanks again to everyone who helped me sort this out. This site is great and I know I can always find the answers I need from the guys who know.

fantasygoat

Sounds like there was corrosion in one of the connections causing signal issues and pulling and reseating the connectors "cleaned" the contacts.

Barry's70LT1

Sounds reasonable. Problem seemed to be that you were not getting the 12V from the starter to the TI harness.

68blvert

Pull connectors back apart and inspect for fretting/ corrosion. Sometimes you have to use magnifying glass to see fretting. Clean connector terminals with diamond tipped connector cleaner or sometimes just an electrical contact cleaner sprsy, like the kind from CRC, will work. Coat terminals with Nyogel 760G/ GM part# 12377900 or Stabilant 88 or any other real good electric contact sealer before reconnecting. It's also possible you have frayed wire inside the sheathing and all the movement has caused the wires to "reconnect" for now. Intermittent electrical problems are the biggest pain of all to chase. They usually pop up 100 miles from home...at night...in the bad part of town...during a down pour.

ctmccloskey

Hello there 69 coupster,

I have the same ignition system (K66) that you do and it came on my 1968 former L71 Corvette. There is a man named Dave Fiedler who repairs these ignition systems properly and he really knows the system. Dave has a company called T.I. Specialties You can find him online or you may call him at the following phone number: 1-765-962-4265 He is located in Indiana I believeand his services are very good and quick to boot!

The problem you had sounds like the ignition switch to me but I would call and get to know Dave.
T.I. Specialties rebuilt my entire system and updated my amplifier, he even rebuilt the distributor for the system. After getting it home I took all the parts and bagged them up and packed them in a box. I am using a MSD ignition currently but will be switching over to let my new Holley Sniper Stealth EFI system control the timing as well as the fueling. My MSD billet distributor has to stay so I have a Mechanical Tach drive but it can be made to work with my Holley System.

I met Dave at Corvettes@Carlisle back in the 90's, he was so knowledgeable that I knew he was the guy to help my T.I. system. He has the parts and resources to help with any kind of K66 issues.

GM started using the K66 T.I. Ignition system in 1964 on the Corvettes. I have seen a lot of them on the more optioned Big Block Corvettes. While rebuilding my 427 I had a 1970 LT1 engine in my C3 for a while and the ignition worked great with the small block as well.

There was a fellow Forum member 673x2 who claims Dave wanted to charge him ridiculous money to rebuild his system. I had the whole system redone and he was more than fair with me. Your call my friend as there are varying opinions regarding Dave and his services. He knows the system Very, very well. I trust Dave Fiedler myself and would use him in a minute if I needed to. I removed my complete ignition system to use Higher performance parts only, I am glad it is safe and boxed up.

fogaley

If its not been suggested then I believe that the starter solenoid should be removed and the cap/end removed. You will find one of the two
contacts attached to the small studs is broken off. I have seen this several times. Scott

7T1vette

I was thinking that the starter solenoid was the cause of your problems before seeing the prior post. I agree. When cranking the engine, the 12vdc to the ignition comes directly from the "S" connection on the solenoid. When you release the key to "run" position, the power to the ignition comes from the ignition switch and thru the resistance wire. If the "S" contacts (inside the solenoid) have an issue, your symptoms would show up.

Big2Bird

So hook a meter up to the post, and watch while an assistant cranks it over.

7T1vette

Yep. "S" terminal should have 12vdc on it when ignition key turned to START. It should have 0vdc when in RUN position.