<84 Vette>
I seem to be having some minor to major electrical problems. Thinking it could be a grounding problem but i don't know. First off, when i got the car, none of the HVAC/Gauge switch lights worked. The lights in the gauges themselves worked though. So i found the fuse and it was blown so I replaced it and found almost every light in that circuit was burned out so i replaced a few here and there and it seems to work fine, no big deal. I say this because it could have relation with the other problems. So I'm cruising main street and my car just dies along with my fan (always runs). Check engine light doesn't light up anymore (should light up when key on, engine off). So i realize, "dang, the ECM has no power". so i test light the fuse to the ECM and its hot on both sides, but realizing there's also another power line to the ECM i find the fusible link at the bulkhead and check it. All good. So i'm baffled. So i get pulled home by chain and when i'm almost home the check engine light pops up so i reach down and flick the key and boom she fires off. Been working for a couple days now. Thats the third time that's happened though. So then last night I'm coming home and i jerk the E-Brake for a slide curve and my choke light lights up? So I chuckle and am like "what the heck?". This morning I pulled it again and this time my Choke and my Hatch Ajar light come on. I have no idea what's going on. I didn't start noticing any of this until after my fuel pump locked solid a week ago and i replaced it. The key was turned on and off a lot during the diagnosis of the fuel pump tho... Any ideas would be appreciated

 

Quick Diagnosis:

Gremlins.

They've infected me too.

Good Luck my friend.

 

A choke on a EFI car? Have you converted to carb or ?

I'd start by cleaning all the grounds. If that doesn't kill the gremlins them get some of that electrical cleaning spray and start cleaning every connector you can get to, all the while looking for frayed / broken wiring at the connectors and such.

 

Well it's TBI EFI but youre right, it shouldn't have a choke but that light is on the stock Cluster, unless the choke corresponds to the cold start injection? But anyway, where would I start? Under hood? In dash? ECM?

 

IMO you are on the right track with checking grounds- I would also clean the battery terminals and clean up the other end of the batt. ground cable. Also, check the starter end of the pos. batt. cable for looseness. Intermittent electricals are frustrating, you need to diagnose when they are misbehaving. It would really help you if you had an FSM or at least a wiring diagram.

 

I'm perplexed by "I jerk the E-Brake for a slide curve and my choke light lights up?" Not sure that this operation is a real good idea but it's your Vette....LOL. Anyway, you might check the wiring and switch at the E-Brake for evidence of a short to ground. I have heard of stranger things causing electrical problems with the engine.

You really need to start with the ground straps though. I'm trying to find a sketch of where all the grounds are. Do you have a service manual?

 

When it isn't working correctly, that is when you start diagnosing the electrical circuits to find out where power stops. You need to measure voltage drop across all ground wires with an electrical load to prove you have a low resistance connection to ground. When you verify good grounds, then you measure power from the battery positive terminal to the fusible link to the ignition switch and past the ignition switch to all devices. Almost all power flows through the ignition switch and the ignition switch has three separate contacts (at least in my 87).
Do yourself a big big favor and buy the GM service manual and the electrical diagnosis manual if the 84 has one, they are excellent for diagnosis.

 

My situation may or may not help. I was chasing electrical problem for a while. One day I happened to notice the condition of the weather stripping along the hood seal was dried out and water was dripping down and getting on the wiring that goes from the firewall into the car...the group of wires behind the distributor.

Don't know if my experience applies to your car but might be worth checking.

 

1986coupe has a good point. There are 2 locations on the engine harness grounded to the back of the heads as I recall. Moisture there could aid in causing the corrosion that we have been addressing with all grounds. My C4 is an 86 also but your 84 wiring harness may be similar in that respect

PS Those particular grounds may be a bugger to get to with the heads up against the firewall. But many things are difficult to get to in that engine bay.

 

Open your hood, pour some water down the windshield and watch to see if any water drips or runs into the engine bay. I happened to see it because I had an LED light shininging in that area. I took the seal off, put new weather stripping sealing on, then fastened the seal again.

In my situation it wasn't a ground but rather the water was going on the main wiring harness and obviously running into the car causing electricity to arch whereever it could. I was having my battery run down, blowing lights, burned out the amps on my rear speakers, and watched it not run right. I noticed that when it was wet it was having problems. One time I turned the car off and the heater fan was still running. When I finally noticed that it was a water problem I started pouring water in suspected areas until the problem started. IT took a long time to trace it but it was worth it!

Bill