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I had a strange low voltage issue plaguing our 1988 C4 and it turned out to be fairly simple to resolve. Follow the battery wires and see if you see the branch feeding the car and it's interior. Frequently there are two main branches, one going to the car's accessories and the other to the starter. On the C4's they have a second smaller wire going from the battery Positive connection to the post where the fusible links get their power and then power the fuses and the rest of the car. IF there is any corrosion here then you have issues with everything electric related inside the car. The one on my 1988 was totally corroded and it WAS the source of the problems. I cleaned it off and coated the finished re-assembled post in battery grease which will keep the oxygen away from the surface of the post.
To give an example, my radio was sitting at ~9-10 volts at the input wires. The fuel pump was not spinning properly and would not make pressure at 9 volts DC. Every item inside the coupe was experiencing low voltage until I cleaned the connection under the hood. Immediately after cleaning the corrosion off the post and reconnecting the 7 fusible links (C4) at the post there was full battery voltage at every battery connection point
With your car being similar to the C4 you might have a similar issue. Low voltage will not let anything work right from your ignition coil and fuel pump so I would pursue where the voltage drop is being caused.
The popular tool called a Power Probe would be really helpful here on this Corvette. I used mine to apply 12 volts at places like the fuel pump to verify that the parts are still working before tearing into the car. You can also put Ground anywhere you want, the rocker switch on the Power Probe determines whether the tip of the tool has either 12 volts of 0 volts. It will power up circuits and is protected by a circuit breaker built-in.
The InterState Battery you bought at Costco likely still has access to the electrolyte. Sometimes you have to pry the caps loose but they are often still available to top off the electrolyte. These batteries last even longer if the electrolyte level is maintained at the full point. NEVER put battery acid in a used Battery, I use water from my Reverse Osmosis system and it loves it.
After tracing the wiring diagram it looks like the distributor power wire also powers all the gauges. Could an intermittent ground or failing fusible link be causing my issues? If running the distributor directly off the battery didn’t make the engine run better I wouldn’t think so, but it could possibly explain how the two issues are connected.
It looks like the titty pink wire is what connects to the switch in the steering column. If anyone has any pictures of what titty pink is supposed to look like my PMs are open.
12 volt tester light is on my list of things to buy.
Last edited by Piersonpie; May 4, 2026 at 12:16 PM.
The Titty Pink wire is what I believe people refer to as the fusible link wire that controls the voltage in the old points ignition systems.
Its always been a problem for people who switch over to electronic or HEI distributors because it cuts the voltage from 12vdc down to 10.5vdc to protect the points.
It’s generally in the electronic or HEI installation instructions to replace that wire and run a new wire from a 12vdc source at the fuse block.
Many people don’t replace the wire and may not have any starting or running issues for a long time, then suddenly they have starting and running issues until the fusible link pink wire is replaced and connected to a good 12vdc source.
Reading the voltage at either the alternator or the distributor (with significant RPM) I’m getting a rock solid 14.73 volts. Turns out the “spikes” I was seeing yesterday was the engine nearly stalling out and turning the alternator slower. I’ve cranked up the idle speed on the carb, now it will idle for ~20 seconds without throttle input before dying.
I’m thinking there’s an issue between the power wire at the distributor and getting a good spark. Bad new module? Burnt out plug wires? Already fouled plugs? We’ll try more stuff tomorrow.
I took the passenger side dash out to gain access to some of the gauge wiring. I don’t have any HVAC in the way so I could actually see quite a bit. Didn’t see any burnt wires or anything else out of the ordinary though.
The car was running well before the battery discharge so troubleshoot from there, you seem to be going for the shotgun approach. A dead battery would not effect the cap or rotor, pulling the distributor should not solve anything if it was running good before, just adds another ? mark to the troubleshooting. Slow down... Look for what could have changed, it should be electrical, not timing, carb/fuel, or distributor position. Your gauge fuse is blowing, sends me to look at wiring, links, etc.. and X3 on the coil replacement and I hope you got a good modual replacement... good luck
The Power Probe is way more than just a 12 volt test light. I have two of them a Power Probe 3 and a PP 4. The newer PP 4 is very useful on newer computer controlled cars.
Coils are something that we see failing more often today. I have been through 2 or 3 of them in the past 10 years. The problem is that he already replaced the ignition coil and nothing happened.
IF it was anything but a Corvette I would suggest checking the Ballast resistor on the ignition coil. Since we have the resistance wire in place of the ballast resistor I am not sure the voltage at the ignition coil.
Have you tried to check for any Alternating Current (AC) in the output power? It would indicate that your alternator's diode bridge has a problem. AC can make a mess out of the electronics if you have much on your Corvette.
One way or another we will figure this one out with you and the help of others here on this Forum.....
Corrosion on a electrical connection can be forced to work with enough voltage and power. If you have corrosion on any of the battery connections that feed your fusible links the voltage will steadily drop as the resistance builds up.
I had one Car that had a tiny pin hole on an electrical wire feeding the fuel pump. Water got into the pinhole and started corroding which caused problems that were tough to diagnose. When the car was first started it would run fine for about 30-45 seconds and then just shut off and it would not start until the connection cooled off overnight.
If you have a damaged wire like the one I had it would explain why the engine shuts off so soon. I would look at the power wire feeding the fusible links and see what the voltage is without the engine running.
When you start the engine please monitor the voltage on the ignition coil. I would like to know what it does right when the engine is shutting off. I would like to know if it is going too high a voltage or too low a voltage right before shut off.
In the OP’s first post, he left the lights on which drained the battery.
There was no key in the ignition, the engine wasn’t running, he made no modifications to the car so I can’t see how the battery going dead could cause any failures in any components.
But, whenever you jump start any car with jumper cables or a battery jumper, there is potential to damage other electrical components.
I have to agree with the above that the issue would be within the ignition system.
Either a resister wire, fusible link, ignition module, or coil was possibly damaged when the battery was jumped.
Try pulling the belt off the alternator and starting the car and check your voltages.
You should see battery voltage.
If your alternator belt turns the water pump, don’t run it very long.
I would take the alternator in and get it tested to make sure the diodes are not fried and that it is functioning as it should.
Check your voltage at the distributor and coil while cranking the engine but not starting it.
Next run a 12vdc wire from the ignition location on the fuse block and bypass that pink wire going to the distributor, check the voltage during cranking only, then start the engine and check voltage.
Keep us posted!
Last edited by OldCarBum; May 5, 2026 at 01:04 PM.
Thanks for the suggestions everyone. I’ll try them in order, starting with a different coil. Since they’re on the same circuit would it make sense that an intermittently shorting/bad coil could cause the gauge fuse to blow? I have a few more 10 amp fuses to spare if a different coil fixes the rough running engine.
Last edited by Piersonpie; May 5, 2026 at 05:44 PM.
If your jumpstart fiasco did damage module & coil simultaneously, your new module may've already become damaged by a damaged coil.
Suggest buy a good, top quality OE type module & coil and replace as a pair
Then sell/trade for much newer generation vehicle.
Well the new coil seemed to do the trick. Much smoother, although with a little bit of engine shaking missing still. Well enough to take on a trip around the block and revving it up a bit. Afterwards it got even better, so I suspected the new plugs were fouled from running with a bad spark. Sure enough, we had some good ones and some bad ones.
The darkness of the plug was directly proportional to how hot the header tube was where it came out.
As for the gauges, I tried an another fuse which worked for about half a second. Then I found this. I’ll have to get my wiring diagrams out again to see how it truly goes, but I don’t think the black/pink wire is supposed to tie into the (titty pink?) wire in two different spots then house wire nut into a scarily thin red wire which then plugs into the lamps terminal of the fuse box.
Rest assured this will be fixed before I hook the battery back up or start the car again.
Last edited by Piersonpie; May 5, 2026 at 09:37 PM.
Well the new coil seemed to do the trick. Much smoother, although with a little bit of engine shaking missing still. Well enough to take on a trip around the block and revving it up a bit. Afterwards it got even better, so I suspected the new plugs were fouled from running with a bad spark. Sure enough, we had some good ones and some bad ones.
The darkness of the plug was directly proportional to how hot the header tube was where it came out.
As for the gauges, I tried an another fuse which worked for about half a second. Then I found this. I’ll have to get my wiring diagrams out again to see how it truly goes, but I don’t think the black/pink wire is supposed to tie into the (titty pink?) wire in two different spots then house wire nut into a scarily thin red wire which then plugs into the lamps terminal of the fuse box.
Rest assured this will be fixed before I hook the battery back up or start the car again.
What even is going on in that picture? Does that red wire get REALLY hot (and immediately burn a fuse)? AFAIK, PNK/BLK is related to the ignition key and seatbelt warning buzzers. Perhaps these got repurposed by a PO? Or the buzzers have a dead short? If you pull that red lead out, does your fuse still blow? Do you lose any functionality?
My post #22 shows the black/pink wire being the spot where it splits from the ignition switch and goes to power the gauges. The other half of that T is the power wire of the distributor.
I took the weird octopus out and hooked up the black/pink wire directly to the ignition terminal. Is this how it’s supposed to be? I’ll look for my more detailed wiring diagram book here shortly.
I know the OP didn’t do it!
Never, never use twist on wire connectors.
They are manly designed and used for solid household ac wiring and not for stranded wiring.
Either use solder, solder splices or proper crimp on connectors.
I suspect the “creative” wiring modifications were made when a previous owner made the power windows able to be used with the ignition off. Luckily with the ignition hooked into the proper port I didn’t run into any issues. The car is running pretty good at this point. Still not all the way as well as before, there’s some occasional misfires, but with an Italian tune up and some WOT runs I hope to clear the carbon deposits from the combustion chambers.
Some idiot at some point couldn’t get the door ajar light to turn off, so he removed the light bulb. When I took the gauge panel out I found the socket all the way on the stud for the temperature gauge.
That definitely seems like it could cause a short. Fed the box my last 10 amp fuse, and it worked! The oil pressure and water temperature gauges went to their default positions rather than maxed out in either direction. I broke a socket for a different bulb, so I’ll have to replace that first, but once it all goes back together I’m fairly confident it’s a good fix. What a weird/awful coincidence that this happened at nearly the same exact time as my dead battery.
Luckily I didn’t have to tear it down too far to find this.
Last edited by Piersonpie; May 6, 2026 at 11:54 PM.
You know why your car threw you this curve don't you? You thought it was time to sell and move on, it's showing you it still has mysteries to figure out.
But one thing is obvious. The C3 is on it's way out, just do't let it know because it will let you down and leave you stranded when you least expect it. Just because i's a car doesn't mean it doesn't have feelings. Good luck on your search. That's half the fun.
This could not be more true. This most recent fiasco has confirmed my decision. I love it dearly, but I’m a bit tired of such little things that take up so much of my time and money. I want a break from it, at least for a bit. Besides, newer cars aren’t known for having electrical problems, right?
Don’t tell my daily, but I’m thinking about trading it in too…
One thing I can say is I’m eternally grateful for everyone that has helped me on the forum throughout the years. When I first bought this car I didn’t know the first thing about engines, carburetors, suspension dynamics, or barely anything about electricity. Still maybe not that good at the electronics parts, but the people and resources on here have been invaluable in keeping this car alive and on the road, and for that I say thank you. Way better than any computer algorithm or repair manual could ever hope to be.
Last edited by Piersonpie; May 7, 2026 at 12:19 AM.
