Hi....I replaced the ignition and A/C wire harnessess on my 70 454 w/auto tranny. I checked and re-checked the wiring and followed the wiring diagram as shown in the Corvette manual and the build manual. Everything is as called for. The purple wire to the starter is on the "S" pole, the yellow wire is on the "R" pole, and the red wire with the battery wire is on the center pole, and the black ground wire is connected to one of the starter attachment bolts. I checked the starter at Advance Auto and it checked out OK. The 12 gauge red wire from the ignition harness is connected to the battery terminal at the horn/buzzer relay. When I turn the ignition key, the buzzer sounds, the seat belt light comes on, and if the door is ajar, that indicator light will come on as well.

But when I turn the key to ignite the engine, nothing happens; no clicking, no turning over, nothing. It's as if the circuit is completely open.

I also replaced the shifter cables, but made sure to make any necessary adjustments with the new ones. So, could my problems be with the neutral safety switch, or could one or both of the fusible links be bad, even though the harness is new?


Any and all musings will be seriously entertained......thanks.

 

The purple wire should have 12 volts when the key is turned to the start position. If not the neutral safety switch is most likely out of adjustment.

 

What he said, need power when the key is turned all the way. The saftey switch will keep that from happening.

 

I have conducted a continuity check on the purple wire from the starter to the junction block on the firewall, and from the purple wire slot on the firewall to the Neutral Safety Switch (NSS), and from the ignition switch purple wire lead to the NSS, and from the ignition switch purple wire to the fire wall slot. All have continuity. I have also run a continuity check on the red wire from the starter to the "Battery terminal on the horn/buzzer relay, to make sure the fusible links are OK; no problem there. I have conducted a voltage test on the red wire at the "Battery" terminal on the horn/buzzer relay, and at the starter, they both indicate 12.5 Volts. I unbolted the ignition switch and probed the purple wire tang to the red wire tangs and there is continuity, so I'm assuming that the switch is OK. I opened up the NSS and found that the contact tang between the two purple wires was bent and constantly in touch making a bridge between the two connections, regardless of the position of the slider. I fixed the contact tang and put it back together. I'm assuming it works just fine, since I'm getting continuity when the shifter is in neutral, but not when it is in reverse or drive. I still haven't attempted to start the car, since I still have to bolt up the steering column. But if I still do not have ignition, I believe that I might just go mad (or something approximating that, by going to the Starbucks and having a Vente latte..... : ) ......But seriously, I need any electrical experts out there to clue me in on what I might be missing in my setup or diagnosis.

One other thing, there is a relay on the firewall next to the wiper motor; I believe it has something to do with the T.C.S. circuit. When I have the ignition "on", the relay warms up and I hear a click coming from it, and the Dark Blue wire from the sending unit on the right side cylinder head, leading back to the TCS relay also feels hot to the touch. I have replaced this relay previously because the Pink/Black wire had fried all the way from the sensor to the relay and on to the junction block at the firewall. Any ideas.

 

OK....... just to keep the forum informed; I was able to at least get power to the starter when I engage the ignition key. From the looks of it, the ignition switch and the neutral safety switch were the culprits for a lack of juice to the starter.

So....new problem....the starter bendix doesn't engage the flex plate. Does anyone know if I have to add more shims, or what? I have a shim in place now, which is what the starter was originally equipped with. FYI, I replaced the original flex plate with a TCI one.

I thank you for any advice ahead of time.....

......

 

HOLY cow I have the same problem, only mine's intermittent - I had everything rebuilt and tested, and checked all the wires to the starter and they all checked OK. When it's not starting, I hear a clicking coming from under the console evry time I turn the key to 'on', so I'm guessing there's some sort of relay under there? Also, is the neutral safety switch on the shifter assembly or on the trans?

I was bringing a set of jumper cables with me, because every time it happened I could jump and it would fire up!

 

Scary pic Mxscooter...but I like it...... Yes, if you have an automatic, the Neutral Safety Switch is located adjacent to the shifter. It's half moon shaped with four wires, depending on the year. The wires that control the starting sequence are the 2 purple wires(in front of the switch). When the ignition switch is flipped to the start position, 12 volts flow from one purple wire to the other to energize the circuit. The Neutral Safety Switch itself is very simple, but reproduction units run anywhere from $64 (Zip Corvette), to $75 (Corvette Central). Mine was "shorting" because the contact between the two purple wires was constant, whether the slider was forcing them together or not. I opened mine up very carefully by prying the 2 metal hold down clips (part of switch base is metal hold down) located on the slider side of the switch. I used a pair of channel locks and placed one jaw on the bottom of the metal plate, and the other on the edge of the clip, and without squeezing, shifted the channel locks in an arc to force the clip to open up enough to allow the whole thing to come apart. Do not open the clip all the way since it might fatigue and break. Once you are done cleaning, inspecting, and fixing the switch, use the channel locks in the same way to put it back together; just do not squeeze too much, just enough to get the clip to hold the switch together. But if your Neutral Safety Switch is good, then perhaps all it needs is to be aligned properly. Just undo the four screws holding the shifter in place, and turn it sideways to expose the 2 screws that hold the Neutral Safety Switch in place. Loosen the front one, and just loosen the rear one slightly; then lightly rock the switch along its pivot while holding the ignition switch in the start position. Don't give up if the starter doesn't engage right away, since this is a very tedious process. You might also have to loosen the rear switch screw some more, if you don't succeed at first. Also, make sure the slider does not disengage from the pin that move its when the shifter is moved. If indeed your switch is good, then the starter should engage.

There is a relay in the console, but I believe that it's for the A/C, but I'm not sure. I'll look it up later and if it's something else, I'll give you a post.

Just in case, I would also check the ignition switch (but it's a PITA). I believe that mine was just a little bit out of adjustment to where the slider that actuates it was not moving properly through its full range of motion.

Sorry for the wordiness, but I hope this sheds some light......

Later......

 

I forgot to mention MxScooter that the shifter should be in the "neutral" position, and that if you do get the starter to engage, then place the shifter in "park" and try to engage the starter again. If everything is OK, then it should start in either of the two postions, but not in "reverse", or "drive".


...... :o

 

COOOOL thanks! I'll be printing out your reply so I can tear things apart shortly. I put the car up for the winter, and plan on getting down to business with the stupid thing.
I wouldn't be surprised if it was taken apart previously......It was like the last owners had a contest to see how many things they could unscrew and break and then use rusty wood screws and tape to put back together.