Wiring question; Volt Gauge/Hazard

[rfaranda]

I must be missing something here or misunderstanding something... I'm not the most versed at reading wiring diagrams but I'm not ignorant either..

78 280z.. Is the volt gauge wired to the same fuse as the hazard switch?

[SteveJ]

According to what I see from the wiring diagram, you are correct. The voltage gauge and the hazard lights are on the same fuse.

[rfaranda]

Thanks for the reply.... Another question; is the alternator wired in the same circuit?

Here's the problem I'm having. The Hazard fuse blows the second I put one in, hence the hazards and volt gauge don't work, but also the alternator isn't charging. I know on some cars the alternater is wired with the volt gauge. (hope that makes sense)..

[SteveJ]

First off, please stop and organize your problem description. It sounds like you may have at least two separate issues. (By the way, thank you for posting the model year. It helps to be looking at the correct wiring diagram.)

The hazard lights, steering lock switch, and voltage gauge are the ONLY components downstream of that fuse. Right now you have a dead short in that circuit. You have two choices. (1) Keep blowing up fuses until you find the short. (2) Use a continuity meter/ohmmeter to find the dead short.

Having only two components off of this fuse will make it easier to find the short. You'll need to locate Connector C-6 and separate the two parts of the harness. One side has the Red/White (RW) wire from the fusebox. The other has the RW wire going to the voltage gauge. No, I'm not sure which side will be which.

Touch one ohmmeter probe to the R/W wire and the other probe to the downstream (outer) side of the hazard fuseholder. If you get continuity, that is the connector side that is wired straight to that fuse. (Note, you may need to use male and female spade lugs to make contact with the wires in the connectors.)

Now take the second probe and touch it to ground. Almost any exposed (unpainted) metal surface, such as a bolt will do. If you still have continuity, you have a dead short in the hazard light circuit or the steering wheel lock switch circuit.

Disconnect the hazard flasher, and conduct the last test again. If there still is continuity, take off the steering column cover and look for the steering wheel lock switch. Also with the flasher disconnected, test from the Green/Blue (G/L) wire to ground, just in case the circuit is shorted downstream of the flasher.

Do a continuity check to ground on the R/W wire on the other side of the C6 Connector. If you have continuity there, the real fun begins. You'll need to remove your voltage gauge to see if it is the culprit.

As for your "alternator not charging", you'll need to provide a lot more detail on why you think you have a problem. What have you checked? How is the car/charging system behaving? Is your battery dying?

Also, don't be afraid to download a copy of the FSM and read through some of the diagnostics written on the electrical and charging systems.

[rfaranda]

SteveJ,

Thanks for the reply and I apologize for the incoherant post, frustration is getting the better of me. The Z was a Christmas present for my son (15) and its just been one thing after another.... Anyway..........

Alternator:

Every week or so the battery would just die out of the blue... Was at Autozone so I had them run a test, of course the alternator failed. I threw my voltmeter on the battery and get 12.5v, engine off. Start the car and it drops to 12.36v. Put a draw on it (headlights, radio) and it slowly goes down.

I replaced the alternator and get similar results, except all readings were about a volt and a half higher.. (12.65, 12.5)

Thats pretty much where I left off yesterday. I guess what I was trying to determine is if the 2 problems could have been related, obviously not though.

Thanks.

[SteveJ]

Rob,

Have you tried having your son hold the engine at about 2000 RPM and take a voltage measurement?

That aside, this is my first thought. The 78 is the first Z with an internally regulated alternator. The first alternator could have been bad. It wouldn't surprise me if they gave you the wrong alternator at Autozone. For future reference, tell them an 81 280ZX for the alternator. That way you'll get an internally regulated alternator.

Second thought. You might not have enough tension on the alternator. Read the FSM (Download it from the link in my signature.) and get a good idea of the tension needed. Another member here told me he needed to use a broom handle to get enough tension on the belt. I haven't changed out an alternator belt in about 9 years, so I have forgotten what I used for leverage to put enough tension on the belt. Of course, don't go overboard or else you could damage the alternator.

Third thought. You might have received a bad alternator from Autozone. It happens.

Last thought. Check your fusible links. There are two sets in the 280Z. In checking the link, it's important to remove it from the car to check continuity. Also look for damage in the box where the links reside. If you find that you have a bad fusible link, DO NOT replace it with regular wire. You can get replacement links from Courtesy Nissan Parts (link below). If you insist upon making your own, look at the FSM for the area of the wire and convert that to the proper AWG size. From there, you can buy fusible link wire and make your own links.

[rfaranda]

SteveJ,

Thanks for the direction. Here's what I've got:

-2000rpm, no change in voltage.

-Verified its the correct alt.

-Fusible link.... BINGO!!!!

I get continuity from both wires on the alt to the fusible link.... I get 12.49v to the other end side of the link.... Plugged up, 0 voltage at the alternator... "Wiggle" the brown wire and get a hint of voltage at it......

My son thanks you for the help....

[SteveJ]

Honestly, it's mostly just reading what other people have done and doing a little reading and research. (It doesn't hurt that for the last 4 years, I've been doing a lot of debugging wiring in emergency generator controls.)

Have your son start reading the FSM, especially before he tries to tackle a problem on the car. There is a ton of great information there.

By the way, the red links on the Courtesy Nissan page replace the brown links.

[rfaranda]

Well, I spoke too soon... Fixed the links and everything checks out. 12.49v at both leads at the alternator... Ground resistence looked good. No charge at the battery....

Started tracing the blue (I believe sensor) wire. Continuity tests out at the back of the volt gauge. Also traced it the passenger kick panel near the fuse box... Its just hanging there with a bullet connector, not connected to anything. If I am reading the wiring diagram correct that should go to the brake light warning relay somewhere under the passengers seat. (ran out of daylight at this point)

Would that being disconnected affect the alternator?

Thanks

[SteveJ]

If the S terminal never detected too high of a voltage, your alternator would keep pumping out current. It seems like the opposite is happening.

With the negative battery cable disconnected from the battery, check continuity between the B terminal on the battery and the positive battery terminal. (Actually resistance is better at this point since you've already found a dodgy fusible link.) If there is too high of a voltage detected at the S terminal (basically a voltage difference), it will shut off the current. I'm thinking that is what is going on.

Ref 78 FSM section EE pages EE-13 to EE-15.

[Zed Head]

It looks like you're reading battery voltage at the alternator and that the alt is not actually doing anything. Do you have the L wire connected? It should get ~2.5 volts at the connector when the key is at On. As I understand things, the L voltage magnetizes the alternator coils so that they will produce electricity when the alt spins. The charge light (the Lamp that L refers to) should be lit when the key is at On, engine not running, and go out when the engine starts. If the alternator is not producing voltage greater than battery voltage, the light will stay on.

That hanging wire that goes to the brake check relay is also the power for the Lamp. They are wired in parallel. As SteveJ suggests, you'll see it on Page EE-15.

You should read ~14.8 volts at the battery terminals at about 2,000 rpm when the alternator is working and wired correctly (depending on load, like lights, fans, etc.

[rfaranda]

SteveJ: Thanks, thats what I was thinking also. I'll let you know what I find...

Zed Head: Thanks also.. Yes, the L wire is the blue I was tracing. I haven't checked the voltage on it though, I will.... The charge light is working as you described.