I have been experiencing intermittent voltage drop when the car ('94 vert) is parked for a while, sometimes as little as overnight. Pulling fuses to see which circuit is the problem reveals that the 5A fuse for CCM2 is drawing much too much current when nothing is running -- more than three amps, in fact.

I have seen elsewhere in this forum that a short in one of the injectors could be related, but I don't yet have a service manual with wiring diagrams.

Am I barking up the wrong tree, or is an injector problem a possibility? Any other theories are welcome.

Did I mention that I hate electrical problems?

 

The injectors only have 12v on them when the ign sw is in run. You do need the schematic for your year vette and see what is powered by the CCM fuse and unplug circuits one at a time while watching your ammeter that is in series with the battery.

 

That's what I did to learn that the problem circuit was the CCM2. But without a wiring diagram I don't know what that circuit powers -- that's why I asked the question. I'm getting a manual but not for a few days. Is there any online source for a wiring diagram?

 

I'm not aware of any.

 

Not much to go on here. Did you dump out your error codes ?

Anyway, If you suspect an injector(s) shorting , you can pull 1 of 2 injector fuses to narrow down the culprit.

For '94 VIN P :

INJ 1 Fuse (10A) => Injectors 1, 4, 6, 7
INJ 2 Fuse (10A) => Injectors 2, 3, 5, 8

FWIW, the actual firing of each injector is controlled by the PCM and not the CCM.

 

your owners manual will usaly give you a pretty good list of what each fuse powers. Usaly not a complete list but I would start with that and see where it takes you. This might sound strange but trust me. Make sure eveything thing is off and doors closed. Take a 12 volt test light remove the positive batt cable. Install the test light between the cable and battery. The test light will be on bright if you have a draw that is strong enough to drain the battery. Now for the thing that gets forgotten take some wire and hold one end to the positive cable and the other to the battery with test light still hooked up if everything is off and everything shut you should get a small arch and the test light should go out. By doing this you are timing out the timers completing relays ect that could not completed when you disconnected the battery. Now remove the wire and if the test light is on bright you have a draw. The big thing is the test light must not loose contact when putting on or removing the wire. dont forget to unhook your hood lights or you will be going around in circules. If you have a draw. you need to do what you are doing by removing fuses. If you want to try it my way you will have to hold the passenger door light switch in before you start so you can get to the fuses. Remember nothing can be on and all switches closed for this to work. I know that this is long winded and I know I do not explain things well anymore but that is how I have been doing it for over 30 years. me personaly I never use a amp meter to check for a draw because there a so many things that cause a couple amp draw that would take for ever to drain a battery and not light a test light. Hope this helps