HI and how are you? my 76 280z has some major electrical problems and i need great ideas on how to go about to fix these problem.

The car starts and runs great. the headlight turns on and the hazard light also turns on. But the signal doesn't work, the interior light doesn't work, the radio is not working, the windshield wipers are not working, the heater fan is not working. to sum this all up, all these items i mentioned above, i believe there is no power going to them.

Is there a main relay that controls all these items?

i checked, cleaned and tested my fuse box and this is what i got. The side that control all the above items on the fuse box is not havig power. with my test light my test light was not lighting but when i tested the other row of fuses most of them light up only one or two did not light up.

What can cause this issue? is there a break or circuit point that send power or allow power to go to this side (accessories) of the fuse box?

In other to start the car and turn the fuel pump on, i will have to turn the wiper switch on if not the car will not respond to any thing. But with the wiper switch on the car turn on and start up and power goes to the fuel pump. When the car is running and i switch back the wiper switch to off the car dies.

major problems i need a major help. pls help.

when i got this car, it wasn't runing or starting but i have got it to the point that it starts and runs. i did some injectors job, complete brake job and many more to get the car to the condition it is today.

thanks you for very much for the time spent to read my thread and helping me figuring out what causes this issue and fixing it.

1. No, there aren't relays for the wiring unless a previous owner installed them, except I believe the fuel pump and the accessory relay.

2. You'll need to inspect connectors for damage. That means digging into the wiring in the steering column and dash. Also look for damaged wires, splices or wiring color changes.

3. Download a copy of the FSM so you can see the wiring drawings. There are several circuits you're trying to diagnose.

Do you have the cover to your fuse box? If so that identifies the circuit. If not, look at the FSM. Then tell us what you have on each circuit. Please note the position of the ignition key (Off, Accessory, On) so we can tell whether or not the circuit should be energized.

Once you look at the FSM, decide which circuit you want to tackle first and go one by one from one end to the other.

If you don't have a multimeter, you should get one. You can't always tell the condition of a fuse via visual inspection. Being able to detect continuity can help you find shorts and breaks in the circuit, too.

Edited December 6, 201014 yr by SteveJ
Forgot about the accessory relay

Reminds me of an Olds Cutlass $500 special I once bought for the sole purpose of instructing a new driver (a very bad one). Big, tough, cheap = perfect. Unfortunately the electric was pretty scary. Aluminum foil had been stuffed into the fuse box. There were melty sections of wiring, and there was a lot of weird stuff like your windshield wipers energizing the fuel pump. In hindsight, if I were going to keep such a car, I would just rewire the entire thing. I'd buy one of the reproduction wiring harnesses, yank out all the flakey wiring crap, and just replace it all. In the process, I would upgrade to headlight relays and install a heavier alternator output line. I think that would be easier than tracking down all the individual problems AND keeping your electrical system functioning in the long term. Of course I haven't seen your electrical system, so maybe it's not as bad as all that. However, from a distance, it sounds pretty scary.

If that work is beyond your budget, then I'd recommend going from stem to stern on your car and unwrapping/inspecting/repairing/refreshing/re-wrapping every inch of wiring harness. Look for melted spots, funny burnt smells, cut and broken insulation, corrosion, CREATIVE MODIFICATIONS (ahem...), and anything non-OEM. Using your FSM, restore everything to stock. If you have to do any patchwork, learn to do solder connections with heat-shrink insulation. It's quite easy, and it's superior to crimp connections.

But wait... Now that I think about it, maybe the wiper switch was used by the PO as a defeat mechanism to keep the car from being stolen. Maybe it was done on purpose and isn't a short inside a melted section of harness. I suppose there's hope.

Unfortunately I don't know much about the wiring of the main power feeds in the '76. All I can suggest is to check your fusible links and possibly the ignition switch. I think I'm safe in saying the main power lines are the large white and white/red-trace wires you might encounter.

You definitely need to start with a factory service manual for your year of Z, which you can order used off of Ebay or Amazon. You can also download a FSM for free somewhere, but there's nothing like having paper in front of you.

Edited December 6, 201014 yr by FastWoman

If the wipers don't work, but the fuel pump does when you turn on the wiper switch, then you might have a wire crossed or incorrectly connected in the ignition switch area. You have power up to that area, because the wiper switch is letting power flow to the fuel pump relay (under the dash above the hood release handle) or the pump itself, when you turn the wiper switch. I would focus on all of the wires to the ignition switch and the headlight/wiper stalk, and make sure that they all go to where they are supposed to go.

A member of this forum, Saridout, completed a really nice color wiring diagram for the 1976 year. It is really easy to trace the circuits with the color added, plus you can zoom in on the areas you're interested in with Adobe Acrobat.

http://www.classiczcars.com/forums/showthread.php?t=36494&highlight=1976+diagram

I was tempted to say that the PO may have used the wiper to carry power to the fuel pump because he couldn't figure out how to fix it properly, so he just found an ignition-switched source that he could easily turn off in an emergency.

Addendum: I looked at the color 76 diagram and traced the fuel pump wiring. I am even more convinced that the PO couldn't figure out the fuel pump relay so he took 12VDC from wherever he could find it.

Edited December 6, 201014 yr by SteveJ

1. No, there aren't relays for the wiring unless a previous owner installed them, except I believe the fuel pump and the accessory relay.

2. You'll need to inspect connectors for damage. That means digging into the wiring in the steering column and dash. Also look for damaged wires, splices or wiring color changes.

3. Download a copy of the FSM so you can see the wiring drawings. There are several circuits you're trying to diagnose.

Do you have the cover to your fuse box? If so that identifies the circuit. If not, look at the FSM. Then tell us what you have on each circuit. Please note the position of the ignition key (Off, Accessory, On) so we can tell whether or not the circuit should be energized.

Once you look at the FSM, decide which circuit you want to tackle first and go one by one from one end to the other.

If you don't have a multimeter, you should get one. You can't always tell the condition of a fuse via visual inspection. Being able to detect continuity can help you find shorts and breaks in the circuit, too.

Thanks for this info. i will download the fsm. I have a repair manual in the garage. i will do as you mention about using the fuse box cover and locate what goes where and i will get back to you. thanks

Reminds me of an Olds Cutlass $500 special I once bought for the sole purpose of instructing a new driver (a very bad one). Big, tough, cheap = perfect. Unfortunately the electric was pretty scary. Aluminum foil had been stuffed into the fuse box. There were melty sections of wiring, and there was a lot of weird stuff like your windshield wipers energizing the fuel pump. In hindsight, if I were going to keep such a car, I would just rewire the entire thing. I'd buy one of the reproduction wiring harnesses, yank out all the flakey wiring crap, and just replace it all. In the process, I would upgrade to headlight relays and install a heavier alternator output line. I think that would be easier than tracking down all the individual problems AND keeping your electrical system functioning in the long term. Of course I haven't seen your electrical system, so maybe it's not as bad as all that. However, from a distance, it sounds pretty scary.

If that work is beyond your budget, then I'd recommend going from stem to stern on your car and unwrapping/inspecting/repairing/refreshing/re-wrapping every inch of wiring harness. Look for melted spots, funny burnt smells, cut and broken insulation, corrosion, CREATIVE MODIFICATIONS (ahem...), and anything non-OEM. Using your FSM, restore everything to stock. If you have to do any patchwork, learn to do solder connections with heat-shrink insulation. It's quite easy, and it's superior to crimp connections.

Thanks for your inputs. the cable/wire are in good shape. i need to check under the dash to see how they look

If the wipers don't work, but the fuel pump does when you turn on the wiper switch, then you might have a wire crossed or incorrectly connected in the ignition switch area. You have power up to that area, because the wiper switch is letting power flow to the fuel pump relay (under the dash above the hood release handle) or the pump itself, when you turn the wiper switch. I would focus on all of the wires to the ignition switch and the headlight/wiper stalk, and make sure that they all go to where they are supposed to go.

A member of this forum, Saridout, completed a really nice color wiring diagram for the 1976 year. It is really easy to trace the circuits with the color added, plus you can zoom in on the areas you're interested in with Adobe Acrobat.

http://www.classiczcars.com/forums/showthread.php?t=36494&highlight=1976+diagram

Thanks i kind of had the same feeling but my problem was, i don't the cable/wire coloring. which color cables goes to the ignition switch and which color cables goes to the turn signal/trafficating switch and the wiper and headlight switch. thanks

I was tempted to say that the PO may have used the wiper to carry power to the fuel pump because he couldn't figure out how to fix it properly, so he just found an ignition-switched source that he could easily turn off in an emergency.

Addendum: I looked at the color 76 diagram and traced the fuel pump wiring. I am even more convinced that the PO couldn't figure out the fuel pump relay so he took 12VDC from wherever he could find it.

thanks for your input. Pls help me with color of wire that goes to fuel pump, fuel pump relay, and wiper switch.

Thank you all for the great input. when i wrote my thrread i forgot to mention that, there is a relay close to the fuse box (i believe it the ignition relay. it used to be a big one and it mounted plug in side facing up but i change it coz i thought it was the problem. so now i have a small one). this relay is blue in color. when the key is on the off position in the ignition with the wiper switch on it makes noise but when i turn the key to on position with the wiper switch still on it stops making noise. if i have the wiper switch off and the key off it doesn't make noise.

pls i need cable color for the under d dash. i want to know which cable/wire color and size that goes where. because my signal are not working, no horn, no interior light and no heater. all these things are not working. i can turn the headlight on and off just (car running and car not running). where can i buy an accessory relay or a horn relay for this car (76 280z)

I was looking at the computer today, i saw two white cables that comes from the computer harness pin/head that snap to the computer and they are just hanging. two white cable.

Edited December 8, 201014 yr by rzkas

1. The wire colors are listed on the FSM and in the diagram that Zed Head linked to. For the fuel pump and relay, I just found the fuel pump on the diagram (It's on the left of the diagram about 2/3rds of the way down.) and traced the positive wire back through the diagram. (Black is almost always ground unless it is a black wire with a colored stripe.)

2. Asking about a bunch of different wire colors/sizes isn't probably going to get you far. We don't have them memorized except for the odd color here and there. There are just too many wires to know them all. Also, we don't know if a previous owner hacked into the wire harness. If that is the case, we won't know what color wires were used.

If you look at/print out the BE section of the FSM, you'll have pictures to match up to the components in your electrical system. That is one way to figure out what you have.