Well, damn.

I have a '77 with, lets not mince words here, everything broken. I think it was left parked with a window open, so the entire interior needs replacing, which is actually kind of fun to do, but the real problem is the wiring.

Bubba (or more likely some 16 year old kid who had this as his first car and trashed it, judging by the pot and indie band stickers all over the place) had a little policy; when something stopped working, or if you were really worried about having those wires dangling around the place, just cut 'em. The dash wiring harness was a horror; corroded, cut, filthy, and even burned in places. The only electrical thing the car would do on a mostly reliable basis was start. Knowing this, I ordered a new wiring harness (77 Early, alarm in fender, which this is) and proceeded to methodically run it parallel to the old harness, using a wiring diagram to connect ancillary stuff as required. Good idea, right?

Well, no. The new wiring harness has no spots for fusible links; all that I'm left with after hooking up the console, power windows etc, is a bunch of interior light sockets, a few miscellaneous connectors that I haven't yet identified (but which sure as hell don't look like anything you'd plug a fuse into, and this:



Lo and behold, it has a fuse in it that looks pretty good. Only snag is, it runs from the alternator, through the firewall, to the fuses, and then to nothing - the wire is cut.

After that long-winded run up, my questions to you wiser minds are:

1) Where should the other end of the wire plug into?

2) Is this the fusible link I should be looking at with regard to non-starting problems?

3) Do I have the right wiring harness?

4) Should I just give up, burn the house down for the insurance and move?

 

That is an inline fuse holder, not a fusible link; it probably went to an aftermarket stero at some point. Do you have the wiring diagram for you car? It would be a big help, no need to burn your car! Papawana was giving away emailed versions of the wiring diagram to anyone who wanted one, you may want to PM him to see if he has one for your car. I can't answer your other questions, but the manual would help greatly I'm sure. Someone with a '77 will probably chime in.

 

I have a '77. You say it comes from the alternator? Which wire in the plug, if you can get a picture too, does it come from?

It may be the sense wire, which would need to go to the GEN light bulb in the gauge cluster, and then to any switched IGN or ACC source.

The alternator plug only has 2 things. It has 12V constant, the large red wire in the plug, and a small wire either white or brown. If it's brown, you most likely have a GEN light, and that bulb provides resistance and lights if either side falls. Like if the output falls below the level of the battery or vice versa.

 

there are no fusible links in the dash harness, nor are there any inline fuses. I agree that is a modification not required. The wiring diagram is a great idea, as well as the AIM which will show you a general layout of the harness and the connectors

 

It looks aftermarket to me, and is the type of fuse holder that stereos or equalizers would use.

kdf

 

A fusable link is a piece of wire in the harness that is designed to melt if there is a direct short to ground or a load that is too large. Is that fuse holder in the pic part of the old wiring or new wiring ? If part of the old, probably safe to remove it and throw it out. I don't see any fuse holders like that in the wiring diagrahm for 77.

 

You may want to check with Doc rebuild and see if he has one of his wiring sheets for a 77 finished. I looked at one of his for a 72 and it is really easy to read without being an electrical engineer. I am still waiting on him to do one for the 78's.

 

It's part of the old wiring, and not something that I replaced (or even really touched aside from that picture).

(Note: I posted the original message at about midnight last night, so might not have been too clear on what I was getting at)

If that doo-hickey isn't a fusible link, then this raises a greater issue; if I did nothing except pull out the old, broken dash harness and *carefully* replace it with the brand new one, how come the car no longer starts...

I get the feeling that I'm going to have to figure that one out for myself

 

So you replaced the dash harness but not the one under the hood? there are no fusable links inside the car, all are under the hood. 1 by the starter, it feeds all the electrical system. If you have power to the batt terminal at the alternator, then the starter fusable link is good. there is another one close to the large harness plug on the firewall below the brake booster. That one feeds everything inside the car. If you have battery power to the fuse box then that one is good. Does anything electrical work or is it just that it will not engage the starter?

 

Define no longer starts. Does it turn over? If so, ck power at the distributor and see what you have with the key on. Also check when attempting to start it. You should have at least 12vdc depending on battery charge.

 

I should have been more explicit:

It's totally dead. Doesn't turn over, no electrical activity at all.

I'm not able to get to it until later tonight, but I think the first point of business might be to check the battery isn't dead; after all, with the wiring the way it was, who knows what could have been slowly draining the thing. That would be blindingly-obvious-problem number one.

Next up, I'll check the harness plug behind the firewall - I noticed it had a ton of dirt/corrosion on all the connectors, so I cleaned 'em up a little - if I somehow didn't get the harness seated correctly into the plug, that would definitely be blindingly-obvious-problem number two.

Assuming that I have power from the battery, I'll check power battery at the alternator, and go from there.

I gotta say, you guys are great. I really have no clue what I'm doing, but you've all been extraordinarily helpful and generally awesome about helping me out

 

Update:

Battery is good - I've been mostly leaving it disconnected while I work on the electrical system, and it seems to have a pretty solid 12v coming out of it.

Car doesn't turn over, no dash lights/any life at all when battery is connected and I try to start it. Nothing at the distributor, haven't tried checking power at the starter yet. Will try that later tonight, if possible.

Is there something really, really obvious I could have misconnected or just plain overlooked while putting in the new dash harness that would cause this?

 

If you feel you have the dash harness in correct, or as close as you can get it, I would move on to the starter harness, if the PO had chopped it up as much as you say under the dash, he may have rewired the starter harness. Mine was all cut and spliced, I just tossed it and put in a new one from the Doc. Also, check all your grounds!

 

If it was starting before and now its not after you changed your dash wiring harness, you may want to check to see if this harness has wires going to your neutral safety switch. If in fact its part of your harness and its not properly connected your car wont start.

 

Oh, things are definitely hacked to pieces under the hood; so it's quite possible I'll have to replace the starter harness. Will check grounds also.

I hadn't thought of that. Neutral safety switch should plug into the console near the shifter, right?

 

Right. There should be a 2-wire connector which links to the NSS in the console. That switch has to be "made" for the car to start. That's likely your problem with the car not starting. You need a good wiring schematic for your year/type car. The GM Service Manual has one, your harness should have come with one. If you determine which connector is for the NSS, just jumper it to try the car out. BE SURE YOU ARE IN PARK (if auto) OR NEUTRAL (if manual) BEFORE YOU TRY TO FIRE THE CAR UP.
If the engine harnesses don't look too cobbled-up, your new one should work just fine with it.
P.S. You surely don't want any "fuse links" inside your car. They are designed to burn-up/melt when they see too much current. You need to be fused on everything in the car.

 

Are you getting any power in the fuse block? Start tracing the power from the battery. Since your harness is hacked, not sure where all it might be going. Ck from your starter and go out from there. A 12vdc test light will be your best friend so you can pierce the wire to check splices and connections. Good luck! I agree if your under hood harness is really hacked, you should replace it. It would be sad to see your vette turn into a wienie roaster.

J

 

Thanks for all the feedback. Sadly, I'm slammed next week and won't have much time to spend with it. However, everything seems grounded correctly, and if I get a chance I'll check the fuse block.

The highlight this evening was the Neutral safety switch. Rather than wiring it into the shifter, our good friend Bubba just cut the cables and twisted the ends together...

 

I think we shared a former owner! Another item to check is the ignition switch, in case it was by-passed or otherwise Bubba'd. When I got my 76, the ignition switch sent power to the motor, but the start position was broken. My P.O. solved this problem by wiring a push button switch directly to the starter. He just hung the wire over the steering column.

Since you've put in all new wiring harnesses, be sure to buy the 77 wiring diagram. This diagram has been invaluable in working out where things are supposed to be connected and putting the car back together correctly. There was a forum member who sold a really nice color version where the lines corresponded to the wire colors. I bought the black and white version from Corvette Central where wire colors are marked on the diagram.

 

My first suggestion was going to be to check the neutral safety switch, but since you have no dash lights, and I am guessing no gauge functionality, you probably do not have a good connection at the bulkhead. Did you use dielectric grease on the connectors from the engine compartment to the new fuse block/bulkhead connector. The plating on the connectors corrodes over time and does not make good connections. The dielectric grease helps to ensure better connections.