Gauges and Fusebox mystery

[spikeyamir]

I just finished retrofitting my 76 280z with SU's and it starts and runs great! Only problem is that my gauges don't work. The turn signals also don't work although the hazard switch does. I did some reading and searching through the forum and found some very helpful information but I just can't seem to find the problem. I looked at the fuses and three spots aren't getting current. I attached two pics with yellow boxes around the locations on the box that have no current. I have tried tracing those wires and can't find what they go to. If anyone could help me identify these wires and/or tell me what I could try I would appreciate it. I'm trying to get the manual that everyone around here is talking about but money is kinda tight right now (college student). Again any help would be greatly appreciated.

[Valerie1043]

if your 76 is anything like the 77 my bf has, the two top ones are for the right and left headlight. he found a picture the other day that is not in front of me at the moment so i forget which one is for which headlight. the one on the bottom i can check for you. in fact, i'll see if i can find the link for the picture so you can take a look at it. just hold tight till then.

[spikeyamir]

Thanks for the quick response. You said the top two were for the headlights? Hmm, I think both my headlights work well. Let me go double check...

Thanks again!

[spikeyamir]

Duh... yes, the top two are for headlights and sure enough, they work. So, that leaves the little guy on the bottom. Could that have something to do with the gauges I wonder...?

I'm patient...

[bigoak]

Get the Factory Service Manual at carfiche.com

Student discount pricing available (it's free).

http://carfiche.com/manuals022/cars/

If the manual beside you car says TNA, don't get excited...it's temporarily not available. They cycle them on the hour as they don't have the download capacity to host all at once.

Here is the fuse map from the '77 FSM (I assume it's the same).

Good luck with the electrical challenges...

Cheers,

[Nissanman]

Here are the fuse blocks for the '75 - '77 Z's.

I think there may be a fuseable link in the engine bay that feeds the headlamp fuses.

I tried tracing the wiring on my Haynes diagram, went blind very quickly:disappoin

[Rockr69]

The one on the bottom right is for the charge lamp in the voltmeter. Connections to check are behind the glove box at the main junction block and the alternator. As for wiring diagrams the most kickass one I've found is at, http://www.colorwiringdiagrams.com/, also known as Prospero's Garage. Every do it yourselfer with a classic Z should own one. $17 bucks plus shippng. You can't even go to the movies for that! Just remember they use the U.S. Postal service, so if you have a P.O.Box have them ship to that. Believe me I know. I had wait for it to be returned to sender before I got them my box #, but it was sure worth the wait. I wish you luck. Dan

[spikeyamir]

So, this has taken a very different turn than I expected. I think my fuses are ok. What could be the issue with my gauges, tach, and turn signal lights? Doesn't the hazard switch work off the same relay as the turn signal switch on the steering column? If so then why do the turn signal lights work with the hazard switch but not with turn signal switch? I've only got experience on old VW Bugs and had to do this on my 74 Bug. This one's a bit trickier it seems...

Wow, sounds like I've got my work cut out for me. Thank you for all the help and responses. I'll have to do some hunting tomorrow with a test light. Any help with possible places to look would help greatly.

THANKS!

[spikeyamir]

Browsing through the FSM (thanks bigoak) I found some troubleshooting info that I attached below. Considering that my Z DOES indeed start and run could it still be the ignition relay? It says if your gauges, along with turn signals, don't work, to replace the ignition relay... Hmm.

[Nissanman]

The trick is that the IGN relay is driven by the IGNITION signal, i.e. the key switch is is the ON position.

The contacts of the IGN relay then provide power to things various, as the FSM details.

Separate from the cars IGNITION system as such:rolleyes:

[geezer]

I'd recommend getting yourself a good wiring diagram that is specific to your year Z I got one like Rockr69 pointed out because my eyes aren't what they used to be. What an improvement over trying to see the factory diagram with a magnifying glass. I don't have one for a '76 though.

In order to diagnose an electrical problem you first should have a thorough understanding of how the system operates. There is no better way to do this than studying the wiring diagrams and understanding the components involved in a particular circuit. Visually check the connectors & harness in this circuit. Try gently manipulating the connectors to expose a temporary power outage or loose or poor connection due to corrosion. On cars this old it never hurts to check the integrity of the terminals and clean them. If nothing obvious turns up, use a digital multimeter set on the resistance function to first do a :

Continuity Check (open in the circuit)

1. Disconnect the battery negative cable

2. Start at one end of the circuit and work your way to the other end ( at the fuse block in this case)

3. Connect 1 probe to the fuse block on the load side

4. Check each subsequent point along the circuit with the other probe

This should point out a blown fuse, loose or corroded connector or a break in a wire.

Or use the

Voltage Check method (battery connected)

1. Switch the multimeter to the voltage function

2. Connect one probe to a known good ground

3. Begin at one end of the circuit and work your way to the other end checking for the proper voltage

Shorts

With the negative battery cable disconnected you can test for shorts in the circuit by connecting one probe of your multimeter (set on the resistance setting) to a good ground and the other probe on each segment of the circuit, broken down to increments by disconnecting connectors or relays. The goal is to isolate the circuit in order to narrow the search for a short. The beep indicating continuity will point out a short.

Grounds

I can’t stress enough the importance of ground connections. Dirty or corroded connections are the cause of unwanted resistance, severely changing the way a circuit operates.

These are just a few basic tips that can be used on just about any circuit on these cars. As I said earlier the first thing you need is a good understanding of the circuit in question and that means a good wiring diagram. Good Luck

PS - Avoid using your test light instead of a digital multimeter if there is any chance of letting the smoke out of computers or sensitive controlers.

[Valerie1043]

I was going to tell you to look at the thread I posted before you to look at the pictures, but the guys on here are quick and sent them to both of us. At least I knew where my headlights were at .

and a quick question for anyone who knows...what exactly runs off the ignition when it is on and is the ignition relay needed to run certain things? Could any of it be bypassed? In the 77 280 that was converted to the race car that we have, there is no working ignition...the car runs off a push button and a toggle switch. If the ignition needs to be on for certain things to work, how to do get around that?