Hey Gang,

I have another question and I am really out of my element in this one. I think I have a bad found wire. Before I start listing the stuff that doesn’t work, all of my fuses are good.

My horn, dome light, interior lights, cigarette lighter, radio and horn don’t work. Neither do my dash and gauge lights(I think that might just be a bulb issue). Are all of these items on the same circuit and could one bad ground effect them all?

 

Most of what's not working is on one fuse, may pay to check again using a meter if you haven't already. It is all on the same fusible link at the starter.
Do your tail lights work? If not probably the fusible link has gone open circuit.
Normally a bad ground causes odd things to happen before anything stops working completely.
Test between the outside of the cigarette light and the battery neg to check the ground.
If the ground is bad it is on the drivers side pillar, behind the dash near the light switch.

 

Get on the ground side of any of the lights and check for ground. Do the same for power. You can still have 12 volts, but not get a light if you have broken wires. I use a bulb to check power, never a meter.

 

All those things except the instrument lamps are on the accessory "ACC" fuse. They all get their power from orange wires that are all part of the same circuit. If you have power door locks are they working? They're on the same circuit but use a different power wire. If they are working I'd say there's a good chance an orange wire has broken or something similar. If they don't work check that fuse again and also clean the fuse contacts inside the fuse box. Make certain the fuse contacts grip the fuse tightly. (Disconnect battery first!)

The instrument panel lamps get their power from a low amp fuse labeled IP LPS. It's so high in the box that you really have to work to see it. That fuse is powered via the tail lamps circuit so that they only come on with the headlamp switch pulled. Double check both of those fuses and again clean and check the fuse contacts. If you get power at the IP LPS fuse (with the headlamp switch pulled out at least one notch) and still no instrument panel lights the dimmer rheostat in the headlamp switch is likely burned out. For that matter make certain you turn the headlamp switch **** fully clockwise--that's the dimmer and if turned way down (counter-clockwise) you won't get lights. There are so many lamps that light the instrument panel and gauge pack that it's unlikely they're all burned out.

 

Sorry for my late reply to this thread. I was out of town for a week.

But to follow up, SwampeastMike, My power door locks do not work. I bought new fuses and replaced all of them in the fuse box after I cleaned the contacts. Still dead!!! With that said, I put a multi meter and checked all the fuses as well as the interior light sockets. They show they are getting power. This may be above my head because that makes no sense!!!! I even pulled the radio and checked those connections.

This is the real whopper. While messing around, I had the car started and switched on the heat. My son noticed that as I was sliding the heat over to the right at a certain point the interior lights flashed on. I had taken the bulb out of the drivers side floor and the one overhead between the seats. The only bulb still plugged in was the one in the floor on the passenger side. Like I said, am I in over my head?

 

Oh, and yes Antz81, my tail lights do work.

 

Like I mentioned above, ditch the meter, and either make or buy a bulb. I always use a bulb to check for power problems. I use it often in my line of work. Meter will only tell you if voltage is present. It will not tell you if the wire is carrying enough current to do anything.

 

Helomech! Thank you. I actually just ordered on amazon.

 

Still some more things to check before you claim defeat.

Make certain that the ACC fuse shows power on both sides at all times. Use some fine needle nose pliers to close the contacts slightly and ensure you're getting good connections.

The courtesy lights should have +12V at all times at the contacts connected to the orange wires. Verify. The courtesy lights work by providing ground on the white wires. They have their own ground source (the door jambs via the switch bodies) so problems in the main cabin ground won't affect them. If you're getting +12V at the lamp sockets the next place to look is the solid state module that provides the turnoff delay. Remove the glove box (easy) and look to the right for an orange plastic box (it should be taped to the harness). Disconnect and jump the two white wires on the harness side of the connector and the lights should come on. If not verify that one of those white wires has connection to ground at all time. If not the problem lies between the door and headlamp switches and one of those wires. If one does have ground the problem is between the other white wire and the courtesy lamps.

The "moving the temperature control lever and courtesy lights coming on for a moment" is somewhat telling. The temperature control is purely mechanical via a cable that runs from the console to a lever below the glove box. While this shouldn't happen in a "factory" the linkage at either end or slight movement of the cable itself could disturb poor connections. Lousy aftermarket radio installations are very common sources of poor connections

The power locks also have their own ground source--a screw (one black wire leading to it) into the inner metal layer near the lower front corner of the passenger door. Obviously you have to remove the inner door panel to access

Virtually everything else inside the cabin has a constant connection to ground via a single connection at the far left of the dash near the headlamp switch. While only a single wire to a single connection that ground goes throughout the cabin via a large number of factory splices and wires.

Given the things that are dead you almost certainly have multiple problems. This is because they are in multiple circuits (accessory and instrument lamps) and have different ground sources (independent for courtesy lights and power locks but shared for everything else).

Since it seems that everything powered by the ACC fuse is dead I suspect a problem with +12V as again there are three separate ground sources for the things on that circuit. Like the ground, the power for the ACC circuit (always an orange wire) goes throughout the cabin and has many factory splices. As helomech said be certain you get actual +12V current by using a test lamp.

 

I just took a old but small incandescent bulb, and soldered wires on to it. Wrapped it with heat shrink and have been using it for years.

 

A bulb will work fine if you are checking for power and power is present, but if you are checking for grounds a meter is necessary. I would bet that you have a ground problem and /or open fusible links.

 

Actually you can use it to check grounds. Just need to hook it to a good 12 volt source. Just works backwards, but grounds can have the same issue as power with broken wires. A bulb is almost always the best way to search electrical problems. Trust me, I use them on helicopters almost daily.

 

Only time I use a meter is at work when I am looking for certain voltages. Such as when I am installing a potentiometer like last night. Depending on the position of the arm, it needs precise voltages both + and -. But if just seeing if something will work a bulb is always best IMO. Been doing this since 1991.

 

I worked on DC-8's, 9's and 10's for McDonnell Douglas in Long Beach, Ca in the late 60's to early 70's as an E&R Mechanic and have used both depending on what I was trouble shooting. Many vehicles are notorious for bad grounds and Vettes and pickups top the list, IMHO.

 

Yes, but you can troubleshoot a bad ground with a bulb, just like you can the hot side. Just reverse the process.

 

Are you referring to a battery powered tester with a point at one end and a pigtail with an alligator clip at the other?

 

No. Talking about soldering wires to a bulb. Just get alligator clips to a good positive source, and test the ground. But that will work also. Just harder to use.

 

Not if you're trying to find misswires in a 55 pin Amphenol plug/recepticle.With a meter there is no need for power since it supplies it's own. You've been trouble shooting since 91, I've been doing it since 62.Your way might work, but you're depending on power so if you're trying to find and fix a problem on a vehicle with out any power source how do you do it?

 

But your meter will not tell you the condition of the wire. Your meter will tell you, that you have continuity. One single strand of wire can make a meter read, but it will not carry the amperage required to light a bulb. The op is not talking about wiring being wrong. His was working and now it is not. You are bringing a different issue to this post. For his proposes a light bulb will tell him everything he needs to know and a meter will not tell him the whole story, and it would only cost a few cents to build a bulb set up. I spent hours trouble shooting a position light over 20 years ago that my meter was telling me it was good. A old avionics guy came out with his light bulb and had it tracked down in a few minutes. Meters are fine for finding a wire, like if someone wired it wrong, but it will NOT tell you if your wire has broken wires inside it. Only if it is completely broken.

Your last question is kind of weird. What vehicle doesn't have a power source. We are talking about corvettes here. Not a model T

 

If you really want to know the condition of the wire use a Wheatsone Bridge. If the battery is missing or dead you're SOL.