Hi all,

I could use some help with my starter motor wiring. The car no longer starts, not even a click. 1981 C3 model.

I have put 12v on the starter solenoid and that works so the starter is good
I noticed a previous owner made a bypass on the clutch safety switch:



I checked for 12v on the yellow wire when i try to start the engine and get 12V there indeed so the feed from the ignition switch is also good.

Where i am lost is how the wiring goes from there to the starter motor. A purple wire ends up at the starter motor but a purple-white wire goes from the clutch safety switch bypass somewhere i cannot see.

Should the purple-white and purple wire meet up somewhere? I have checked for continuity but there is none?

Thanks!

 

Purple wire should be hot when you turn the key as it is the signal wire from the ignition switch. It goes to the small "S" terminal on the solenoid (side closer to the engine).

The other small terminal on the solenoid is for the yellow wire which goes to the "+" side of your ignition coil. It is used to bypass the main resistor wire going to the coil "+" during cranking only.

Large terminal is for the hot 12V from the battery cable.

I dont know about the other ones.

 

Is power going through the "by-pass" connection?

 

Only when you turn the key to the "start" position. The solenoid sends 12V to the coil thru the yellow wire. Once you let go of the key and the ignition switch goes into the "run" position, the bypass power from the solenoid stops.

 

Agree on the by-pass wire.
As far as connections between the jumper by-pass and starter solenoid you can upload a copy for a 1980 that should be the same.
Using Willcox Corvette 1980 Wiring manual as reference LINKhttps://drive.google.com/file/d/0B28...tvTC1ITGM/view:
When you see for example a C then a number behind it that represents a connector number.
You can find where that connector is located usually on a proceeding page, but sometimes on a previous page of the manual.
Example (Starter Circuit) page 8A-17 you will see C117 & C100, you can find their location, C117 is Fig. 8A-14 on page 8A-19 and C100 is Fig. 8A-17 on page 8A-21.
I didn't scroll through the manual completely but I think C403 is the 6 or 8 wire connector behind the distributor and is the starter harness.
Edit: It appears that the connector where the jumper by-pass wire is, is connector C117 and once plugged into Clutch Start Switch
Hope this helps...

 

The HEI should not need a bypass wire. This bypass wire is used for points equipped ignitions.

 

It did! Using your help i located the C117 connector. I figured it had be be the culprit as i had the console off before. That connector is just beside the gearstick (manual gearbox) and when i wiggled the wires it would start. So a loose connection there was the reason! Going to clean that up tomorrow.

I am liking this forum! Thanks!

 

If you can get a length of #12 purple wire as a jumper, and (2) 1/4" male spade connectors crimp them to the new #12 wire for a much better connection as a jumper.

 

Thanks but i was considering putting it back on the clutch safety switch. Would the car then only start with the manual transmission in neutral or also with the clutch depressed in any gear?

 

The diagram on page 8A-17 shows the clutch start switch as N/O (normally open) so when you press the clutch pedal in the contacts close completing the circuit.
I see no interlock switch for the shiftier position just a switch on the transmission for the backup lights.
You have a Manual transmission so the clutch start switch is attached to the brake pedal bracket Fig. 8A-14 on page 8A-19
Also see C117 is there also.
If you had a automatic, connector C117 would plug into the neutral safety switch at the gear shiftier.

 

I had a similar problem on my 78 4spd last year and think it should be the same. I can't understand why moving a wire in the console near the shifter has anything to do with a no start. That would be for an automatic.

In my situation,( I have the by pass like you do for the neutral safety switch) I tested 12v at the yellow wire coming from the ignition switch which was great. That yellow wire was connected to the purple which went thru the firewall, under the brake booster, over to the connector behind the distributor on the firewall. I took that connector apart and tested for 12v from the purple wire while someone turned the key to start.. There I got no reading.

My conclusion therefore was somewhere between the neutral safety switch purple wire to the connector behind the distributor cap was broken. I just used a 12v wire, ran it thru the firewall finding a hole somewhere, and then into the connector and eliminated the broken wire. Put a connector on the end and matched it up with the yellow wire. This solved my problem and kept the bypass in place.

That by -pass you have can also double as a theft deterrent. Unplug it when the car will sit unwatched for a time. Even if someone has the key it would not start.

Here is my 78 wiring diagram. Just follow the yellow wire from the ignition switch. I cannot explain the purple and white. I don't see it on the diagram in bmotojoe's link. It should be solid purple but maybe that was the only wire he had on hand doing some repairs.

 

Good to know. But why would someone override this switch? Do not understand. Is this to be able to start the car in gear without the clutch depressed? I did that a few times just for fun when was younger and worked at a car dealership but not sure why someone would override this for their own car?

Well i can confirm that for a manual transmission this C117 connector really is at the gear stick! Purple wires end up there. The switch indeed is attached to the brake pedal bracket.

 

Well like in the previous post this is also true for a manual transmission. I had the same issue you had with no 12V on the purple wire in the connector behind the distributor. But by moving some wires at the C117 connector near the gear stick it starts. Guess that could also have been your issue that you took care of by pulling another wire...

I don't have my wiring diagram for 1981 handy but it shows a point where the purple wire connects to a purple-white one...

 

they peobly did not want to make 2 different harnesses for auto and stick. so they ran the clutch wire thru the non-existant shifter switch area and bypassed it.

 

The photo you provided with the jumper wire inserted is of a short harness called the Neutral Safety Switch Extension Harness
It can be found here LINK:https://www.lectriclimited.com/neutr...harness-107396
If you scroll down a little and click on the Connects To tab it will tell you where that connector connect to.
The Lectric Limited site calls out 2 different main dash harness for the 1981. Automatic Transmission and Manual Transmission.
Can you provide a photo of the connector you speak about at the shiftier?

 

The purple/white wire is part of the main dash harness.
The wire color then changes to solid purple at the extension harness just as your above photo shows.

 

I only had two wires I dealt with. The end of the yellow and the purple leading out to that firewall connector. I replaced the purple, hooked it up to the yellow and all is fine. No other wires or areas were touched so I think I found my problem. At least it has worked for a year now. When you said you had power at the end of the yellow I thought it might be the same but you have a 81 which might be wired differently.

As far as the by pass. You can reach in and start the car when in neutral without having to depress the clutch. However it is dangerous if it is in gear and leaps forward. They do check this at the dragstrip. Dont want you run over the starter.

 

Here it is!

 

Thanks for the photo.
Sorry, all I have to go by is the 1980 electrical manual from the link on post 5 and I don't see that switch in the start circuit.

 

Found this thread which is a few months old but it describes precisely the problem I have with my 81' not getting power to the starter solenoid. I discovered that there is a starter interrupt relay located under the console just forward of the emergency brake handle that has two purple/white wires. I'm not sure of it's purpose but it may be related to the alarm system. In my case, I had not reconnected the relay after gutting the interior. Once reconnected, the solenoid got normal voltage. If you did not want to replace, you could easily jump across it. I'm sure this is old news by now but maybe still useful?