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Very strange electrical issue

cali navy

Member
Joined
Dec 7, 2007
Messages
15
Location
California
Corvette
91 non-ZR-1
I really need some help with this one. I'm a little burnt out on this issue.

I'll start with the previous problem and my fix that might have caused the major issue.
I have had a lot of delay starts recently. The starter would extend the starter, but it would take half a second for it to completely engage and turn the engine over. Once it engaged, the car started immediately without hesitation. If the car was hot, it would not engage at all. Sounds like the solenoid, right? Well, when I run a jump wire or a push button directly from the battery/primary starter cable to the trigger terminal, it would start every time no problem. So, I figured that the issue would be the trigger wire. After inspecting it, I found that the last six inches or so were burnt and even exposed in a few spots. This was caused by having long tube headers and the wire falling out of where it was supposed to be. So, I cut the damaged section off and soldered in a nice new piece of wire with a solid terminal contact. Please trust me when I tell you the connection is solid. It's my job to do this kind of thing.

After I completed the repair and inspected everything else, I went to start the motor. This is the issue.

When the key is turned to "ON", everything operates normally. However, as soon as I turn the key to start, I hear a "pop" from the driver's side of the engine bay and I lose all power... EVERYTHING! The only way to get power back to the car is to pull the negative terminal and let the ECM reset. After I connect the battery again, all power comes back. That is, of course, until I try to start again. It happens every time without fail. The same thing happens with 3 different starters and the battery tests good. If I disconnect the trigger wire from the starter and try to start, I do not lose power. The car doesn't start (obviously), but I don't lose power.

It seems as if the ECM is detecting a high amperage drain and kills power to protect the system. That's good and all, but I need to find this problem. So, here are my ideas.
It can't be the starter. Three different ones and same issue.
Battery tests good voltage, but I don't have a load tester.
Battery cable corrosion? But wouldn't this cause hard starts? When the starter engaged (before) it spun up without any problem.
Trigger wire corrosion? Definitely possible.

One big thing I want to do is replace the primary battery cable and the trigger wire.
Unless I'm mistaken, the primary battery cable goes straight to the starter. Correct?
I do not have the FSM anymore. There was rain and leaking and it became pulp... I need the path for the start signal. I know the key to the allow relay (which is brand new) where it comes out as a yellow 10 ga wire. I know it has to go thru the firewall and to the starter. I need to know what plug it uses and which pin it comes out of. It's purple on the starter end. Does anyone have a diagram, picture or schematic with pinout for that wire? I haven't had much luck finding it online.

I appreciate any information or ideas for a fix. If you have had this problem before, I would really like to hear what your fix was.


EDIT ***********
I almost forgot. No codes.
1991 L98...well, it used to be an L98.....
 
Last edited:

cali navy

Member
Joined
Dec 7, 2007
Messages
15
Location
California
Corvette
91 non-ZR-1
Wow, no replies at all? huh.

Anyways, I found out what the issue was. I wired a 10 gauge jumper from pin-30 (primary power) on the starter allow relay to the start pin on the starter itself. She started up with zero issue. No delay, no jump. Just a good start. That means that the purple original start wire is bad. It has probably gotten too hot and damaged. Heating the wire to solder the last section on was probably the last straw. This wire goes from one of the bulkhead connectors on the firewall straight down to the starter. The problem is that I don't know where it is. I don't want to start rummaging around.

I need to know what connector and hopefully pin number that wire is on. It's an 10 gauge purple wire going from the outside bulkhead connector straight to the starter. I'm going to replace the entire thing and re-pin it. Does anyone know where it is?
 

LLC5

Well-known member
Joined
Sep 28, 2004
Messages
2,299
Location
Wa.
Corvette
98 black 6spd convert.
Wow, no replies at all? huh.

Anyways, I found out what the issue was. I wired a 10 gauge jumper from pin-30 (primary power) on the starter allow relay to the start pin on the starter itself. She started up with zero issue. No delay, no jump. Just a good start. That means that the purple original start wire is bad. It has probably gotten too hot and damaged. Heating the wire to solder the last section on was probably the last straw. This wire goes from one of the bulkhead connectors on the firewall straight down to the starter. The problem is that I don't know where it is. I don't want to start rummaging around.

I need to know what connector and hopefully pin number that wire is on. It's an 10 gauge purple wire going from the outside bulkhead connector straight to the starter. I'm going to replace the entire thing and re-pin it. Does anyone know where it is?



Keeping in in mind that I do not know much about C4's, don't you have a factory security system that controls the engine crank feed to the starter?
 

cali navy

Member
Joined
Dec 7, 2007
Messages
15
Location
California
Corvette
91 non-ZR-1
Keeping in in mind that I do not know much about C4's, don't you have a factory security system that controls the engine crank feed to the starter?

Yes. The VATS system. However, if this was the problem the car just wouldn't start, it wouldn't cause power failure. It disconnects the ground on the starter allow relay so it won't actuate.
 

LLC5

Well-known member
Joined
Sep 28, 2004
Messages
2,299
Location
Wa.
Corvette
98 black 6spd convert.
Yes. The VATS system. However, if this was the problem the car just wouldn't start, it wouldn't cause power failure. It disconnects the ground on the starter allow relay so it won't actuate.


After re-reading your original post, it seems like you may have a battery cable/battery issue. Start with the basics or you WILL be chasing your tail.

1) you absolutely, positively, need to know if your battery is good. Have it properly load tested to verify. Do not by pass this test.
2) make sure that your battery cables are clean and tight, make sure that you cannot twist the cable back and forth after tightening the battery clamp bolts.
3) follow the positive cable from the battery to the starter and make sure that the connections are clean and tight. Follow the main battery feed to the fuse panel and make sure that all the connections are clean and tight. Check the back of the fuse panel (with the battery disconnected) and look for any melted or burned looking connectors.
4) check your ground to the engine. Follow the negative cable from the battery to the engine and make sure ALL the connections are clean and tight. This may include a connection at your frame and then from your frame to the engine, this is absolutely critical and is the connection that is commonly overlooked. Good luck with it. :)
 

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