[ssfast99]

Hello,

I am hoping someone has had my experience to help diagnose this issue for me. Yes I have searched the forum, internet, local crazy guy, even begged the car for a few hours. Here is what I got. Car sat for 22 years partially covered, Grandpa owned it and never mentioned it so we have no idea why it was parked. Found it after he passed in November in the back yard under a car cover with 3 sides tucked up against the rear garage that never opened. I only mention these things to paint the picture it could be anything.

1977 280Z manual

Brand new battery - check
Starter rotates motor from ignition switch - check
Ignition system works properly - check

Weird stuff, the rear running brake lights are always on with battery connected, window wipers work from switch, horn clicks but no sound, and voltage gauge moves when trying to start motor.

I cleaned and reinstalled the gas tank with 93 octane. I replaced the fuel filter which is transparent between the tank and pump. I have no other lights, no dash, no headlights, no blinkers, no door chimes, NOTHING. Fuel filter is bone dry when trying to start. Fusible links are intact and power is consistent on both sides (does anyone have the proper voltage readings for each link?). The fuel relay above the control unit appears new but have not removed. I also have not touched the AFM due to fear of damaging it. My concern is the car isn't getting full power to everything so I don't know if that's an issue or if I am on the right track with suspecting the AFM or fuel relay. If anyone has experienced this or wants to yell at me on what to do please feel free. I also checked the fuel pump, there seems to be some solid bondo stuff covering the connectors so I cannot get my DVOM to contact the wires or nuts.

Thank you all and just a little background I have a lot of mechanical experience but not so much with electronics and this is my first non domestic car so I am excited to jump into this culture and see if we can get this 2.8 screaming down the road.

 

[pilgrim]

About the brake lights - check the brake pedal assembly. The brake light switch is supposed to hit a plastic disc inserted into a spot on the pedal assembly above the place your foot contacts the brake pedal. Those discs crack and fall out, leaving the brake light on all the time. That would fit your symptoms. You could tape a quarter over the hole for now if that's the problem. The discs should still be available.

 

[ssfast99]

About the brake lights - check the brake pedal assembly. The brake light switch is supposed to hit a plastic disc inserted into a spot on the pedal assembly above the place your foot contacts the brake pedal. Those discs crack and fall out, leaving the brake light on all the time. That would fit your symptoms. You could tape a quarter over the hole for now if that's the problem. The discs should still be available.

Thank you Pilgrim, that makes sense. That's a fairly easy fix. Any idea on the other issues? I assume the dash lights are suppose to come on or gauges move with ignition on even without the engine running?

 

[steve240Z73]

First, thank you for having the year of your car in the signature. It helps with providing accurate information.

Second, you need to download the proper documentation to start your diagnostics. That would be the factory service manual and wiring diagram. You can find them here: Classic Zcar Club File Downloads

I would suspect there are some issues with corrosion and maybe missing fusible links. Another member here with a 77 recently got his car running after I got him to focus on the EFI fusible link. It was disconnected when he bought the car. You should measure voltage to ground on each side of the fusible link. There should not be a voltage drop. .

The voltage gauge dropping during starting means that either the battery doesn't have a strong enough charge or corrosion in the wiring harness is preventing the electrons from flowing.

You're going to need to be decently competent with a multimeter to solve these problems.

The horns could be corroded internally. You hear the horn relay click. Sometimes you just need to clean the contacts for the horns to get them to work.

The dash lights should come on with the first click on the headlight switch (and the second). Make sure the rheostat is turned all of the way bright. There's a knob on the dash for that. With the old incandescent bulbs, the gauges won't be too bright. Also, sometimes the wiring connector in the steering column will get too hot and melt down. I've seen that in numerous cars.

Slow and steady wins the race in waking up a car that "ran when parked". You get to find the problems the previous owner had plus all of the problems that crept in while the car was asleep.

If you say where you are, maybe we can hook you up with a local enthusiast who could help guide you to getting the car running again.

 

[kickstand80]

There is a contact in the AFM for the fuel pump. Your fuel pump could be bad. Your fuel lines could be plugged with crud. On the battery + cable or at the starter cable there should be a secondary power wire that goes to the fuse links and fuse box.
Get the FREE FSM here
S30 FSM
There will be a wire diagram in the FSM. Start chasing wires. Get a 12v test light, cheep and EZ to use. U can use it to poke thru wire insulation to check for power on any wire.
Like this one
test light
Good luck and be patient. This will be frustrating but it will be worth it. Revive the Z! and keep them on the road.

 

[ssfast99]

First, thank you for having the year of your car in the signature. It helps with providing accurate information.

Second, you need to download the proper documentation to start your diagnostics. That would be the factory service manual and wiring diagram. You can find them here: Classic Zcar Club File Downloads

I would suspect there are some issues with corrosion and maybe missing fusible links. Another member here with a 77 recently got his car running after I got him to focus on the EFI fusible link. It was disconnected when he bought the car. You should measure voltage to ground on each side of the fusible link. There should not be a voltage drop. .

The voltage gauge dropping during starting means that either the battery doesn't have a strong enough charge or corrosion in the wiring harness is preventing the electrons from flowing.

You're going to need to be decently competent with a multimeter to solve these problems.

The horns could be corroded internally. You hear the horn relay click. Sometimes you just need to clean the contacts for the horns to get them to work.

The dash lights should come on with the first click on the headlight switch (and the second). Make sure the rheostat is turned all of the way bright. There's a knob on the dash for that. With the old incandescent bulbs, the gauges won't be too bright. Also, sometimes the wiring connector in the steering column will get too hot and melt down. I've seen that in numerous cars.

Slow and steady wins the race in waking up a car that "ran when parked". You get to find the problems the previous owner had plus all of the problems that crept in while the car was asleep.

If you say where you are, maybe we can hook you up with a local enthusiast who could help guide you to getting the car running again.

Thank you Steve, I did get the service manual and that is a huge eye opener, thank you for that recommendation. The fusible links have the same voltage on both sides but I do have a question, are all of them suppose to read 12 volts or a signal sweep 5 volt?

I will check the lighting on the dash, that is good insight.

I am in the Chattanooga TN area, would love to meet some fellow Datsun enthusiasts. Not only am I new to Datsuns, I am new to TN.

 

[ssfast99]

There is a contact in the AFM for the fuel pump. Your fuel pump could be bad. Your fuel lines could be plugged with crud. On the battery + cable or at the starter cable there should be a secondary power wire that goes to the fuse links and fuse box.
Get the FREE FSM here
S30 FSM
There will be a wire diagram in the FSM. Start chasing wires. Get a 12v test light, cheep and EZ to use. U can use it to poke thru wire insulation to check for power on any wire.
Like this one
test light
Good luck and be patient. This will be frustrating but it will be worth it. Revive the Z! and keep them on the road.

Thanks Kickstand, I have the FSM, all 631 pages lol, and I will get the Z road going.

 

[steve240Z73]

Thank you Steve, I did get the service manual and that is a huge eye opener, thank you for that recommendation. The fusible links have the same voltage on both sides but I do have a question, are all of them suppose to read 12 volts or a signal sweep 5 volt?

I will check the lighting on the dash, that is good insight.

I am in the Chattanooga TN area, would love to meet some fellow Datsun enthusiasts. Not only am I new to Datsuns, I am new to TN.

The fusible links should have battery voltage on each side. The fusible links are wire links that are 2 wire gauges smaller than the wire they protect with thick insulation so they burn up without exposing wire. In this case they protect the 12VDC wiring of your car.

There are a lot of early Zs in and around the ATL. There is also the Nooga G/Z Club in your neck of the woods Nooga G/Z, though I don't know how active they are. Definitely reach out to them. I'm about two hours from you.

I know there are some members on ClassicZCars.com who live not that far from you, too. S30 owners in Chattanooga area?

 

[ssfast99]

The fusible links should have battery voltage on each side. The fusible links are wire links that are 2 wire gauges smaller than the wire they protect with thick insulation so they burn up without exposing wire. In this case they protect the 12VDC wiring of your car.

There are a lot of early Zs in and around the ATL. There is also the Nooga G/Z Club in your neck of the woods Nooga G/Z, though I don't know how active they are. Definitely reach out to them. I'm about two hours from you.

I know there are some members on ClassicZCars.com who live not that far from you, too. S30 owners in Chattanooga area?

Thank you for the clarification, I have to check which ones but I was getting 9 volts on each side of one link and 5 volts at another. The links are intact as they read the same on each side but the other 2 links show battery voltage. That I assume is my culprit! I will reach out to those groups and atleast get connected at the least. Again, thank you for the help!!

 

[steve240Z73]

Now that I'm at home, I have access to my files.
I think this is the correct identification of the fusible links.

 

[Richard12]

On your horn, I have had the horn relay “click” but the contacts of the relay were corroded. The relay panel is above the right passenger footwell. There is a layout pic in your FSM of all the relays installed on that panel. The horn relay is the smallest relay on the panel. You may prize the metal case from the relay and emery board the contact. Before you go that far, I would hook a test light or dvm to the disconnected wire from the horn and see if you are getting power there. If not, go to the relay. If you are not getting battery voltage to your fusible links, remove the tape on the harness from the fusible links to their connection on the starter. You will find multiple solder connections which corrode and go high resistance. This problem is very common on the 82-83 maximas.

 

[OldSchoolZGuy]

The fusible links should have battery voltage on each side. The fusible links are wire links that are 2 wire gauges smaller than the wire they protect with thick insulation so they burn up without exposing wire. In this case they protect the 12VDC wiring of your car.

There are a lot of early Zs in and around the ATL. There is also the Nooga G/Z Club in your neck of the woods Nooga G/Z, though I don't know how active they are. Definitely reach out to them. I'm about two hours from you.

I know there are some members on ClassicZCars.com who live not that far from you, too. S30 owners in Chattanooga area?

Where did you find the info on the fusible link spec? I looked virtually everywhere during COVID before I started my tear down and complete electrical redesign and as a result of not being able to find anything, I decided to go a different route. I will start posting once I start rebuilding the car after the chassis gets back from the restoration facility.

 

[steve240Z73]

The "2 gauges smaller" was something I found a long time ago when I was educating myself about fusible links. I couldn't give you a specific website now. It just follows logic since the ampacity of a wire is a function of its thickness.

 

[ssfast99]

Now that I'm at home, I have access to my files.
I think this is the correct identification of the fusible links.
View attachment 112398

Hey Steve,

Sorry I haven't responded lately. I appreciate this info. I just tested with battery connected no key in ignition and I get 12.6v at both sides of EFI ignition relay and headlights using the ground post off the battery to keep it consistent. Weird part is I do not have headlights on when I turn the knob so might be an issue with the knob or a blown bulb, haven't checked. As for the Alternator and fuse box and ignition switch I get intermittent 7v to 0v using the same process for the other fusible links. I assume that is an issue but how would it be related to no fuel pump turning on? Also might sound stupid but are the nuts on the fuel pump suppose to be exposed? I have some crazy strong stuff, maybe bondo, over the wire connectors and cannot test if I am getting any voltage there due to that. I'm tempted to just cut the wires and replace the pump. Thanks for everyone's help. Assuming weather permitting I'll be at it the rest of today and tomorrow.

 

[steve240Z73]

1. Post a photo of your fusible links and the fusible link boxes.
2. The problems with your headlights won't be caused by the rheostat for the dash lights. There are fuses for the headlights, and the problem could be with a connector or the switch itself. This issue should probably go on the back burner.
3. I'm not sure you have enough voltage at the ignition switch. When you hold the key in START, the black/yellow wire from the ignition switch goes to the EFI relay to energize the coil that closes the contact for the circuit to prime the fuel pump. You may want to clean up the fusible link box. and verify the integrity of the fusible links (via a continuity check on the link after it has been removed from the box).

 

[ssfast99]

1. Post a photo of your fusible links and the fusible link boxes.
2. The problems with your headlights won't be caused by the rheostat for the dash lights. There are fuses for the headlights, and the problem could be with a connector or the switch itself. This issue should probably go on the back burner.
3. I'm not sure you have enough voltage at the ignition switch. When you hold the key in START, the black/yellow wire from the ignition switch goes to the EFI relay to energize the coil that closes the contact for the circuit to prime the fuel pump. You may want to clean up the fusible link box. and verify the integrity of the fusible links (via a continuity check on the link after it has been removed from the box).

sorry for the extended absence. Here’s a photo of the links. I tested the relay and it’s good, texted the continuity at the EFI computer and all looks good. Zero volts to my relay leads AND computer. Suspecting a bad ignition switch but still can’t understand the low fusible link issue

 

[steve240Z73]

How did you test the relay? Details are important.
What do you mean by "tested the continuity at the EFI computer and all looks good"?
"Zero volts to my relay leads AND computer" What wires did you test? Were those voltage measurements between wire and ground? Did you verify you had a good ground point? What position was the key switch in?

If you are wondering why you might have low voltage on the fusible links, it could be your technique, or it could be corrosion in the wire splices where the wire from the starter splits off to the fusible link blocks.

 

[ssfast99]

How did you test the relay? Details are important.
What do you mean by "tested the continuity at the EFI computer and all looks good"?
"Zero volts to my relay leads AND computer" What wires did you test? Were those voltage measurements between wire and ground? Did you verify you had a good ground point? What position was the key switch in?

If you are wondering why you might have low voltage on the fusible links, it could be your technique, or it could be corrosion in the wire splices where the wire from the starter splits off to the fusible link blocks.

Hey Steve,

I’ll do my best time explain in detail. Hopefully I did it correctly and this can be used for someone else in the future.

I removed the efi relay from the car (located just above the fuel injection computer at the driver front floorboard). I hooked up my gator clicks (wire leads) to a 12 volt battery and connected the ground wire to pin 72 on the relay (ground). I then connected another lead to the positive post of the 12 volt battery and connected that lead to pin 71 (ignition relay / fuse block) and heard/felt the relay click. I moved my lead from pin 71 and put it on 76 (starter motor / ignition switch) and had the same results, a click. I moved my lead from pin 76 and put it on pin 47 (cold start valve) and again had a click. I moved the lead from pin 47 to 36 (AFM) and again had a click. When you study the relay layout this would make sense as all 4 pins have a direction path to ground which will close the switch for pin 70 (12 volt source) to pin 43 (dropping resistor) and pin 39 (AFM) along with a switch from pin 73 (ignition relay / fusible link) to pin 74 (fuel pump) and 48 (air regulator). With the relay switch activated, I had 0.002 ohms between pins 48 and 74, 47 and 76, 39 and 43. I had 0.064 ohms between pins 36 and 72 (this goes through a resistor according to the relay diagram). I had 0.000 ohms for pins 48 and 73 and finally 0.003 ohms between 73 and 74.

As for testing the continuity at the EFI computer, I referred to page EF - 21 for a 1977 Datsun 280Z. Under "engine will not start" it tasks you with checking the following 1 - continuity check using an ohmmeter (on continuity setting) with locations 3, 5, 6, 7, 8, and 9. Then to check 2 - continuity check using a voltmeter with locations 1, 2, and 3. Finally a secondary continuity check using a voltmeter at locations 1 and 3. The location codes are reference the FSM sensor and pin location on the 35 pin connector to the EFI computer at the driver front floorboard. Section 1 location 3a (AFM pin 6 and 8), 3b (AFM pin 7 and 8), and 3c (AFM pin 8 and 9) all read "OK" ( please refer to an understanding of a continuity test for further explanation on a continuity test result if future readers are not aware). Section 1 location 5 ( fuel pump contact points pins 10 and 20), 6 (water temperature sensor pins 13 and body metal/ground), 7 (electronic fuel injection relay: fuel pump relay pins 20 and body metal/ground), 8 (air regulator and fuel pump pins 34), and 9a (ground circuit pins 5 and body metal/ground), 9b (ground circuit pins 16 and body metal/ground), 9c (ground circuit pins 17 and body metal/ground), and 9d (ground circuit pins 35 and body metal/ground) all read "OK" with the exclusion of the air regulator/ fuel pump pin 34 to body metal was not "OK" This results refers you to the wiring figure EF-46. When referring there, you see you are testing from the pin 34 to the air regulator to the EFI relay then to the fuel pump ground. I need to check both the resistance at the air regulator and the ground at the fuel pump. The resistance from the air regulator to fuel pump was already tested above at relay pins 48 and 74 which had a 0.002 ohms reading.

Due to these findings I continued with section 2 location 1 (revolution trigger signal) To do this test you must set your voltmeter to DC and connect your negative terminal of the voltmeter to a body metal grounding surface. Then turn the ignition to the "ON" position with the battery hooked up. At pin 1 on the EFI computer connector, I did not get any voltage readings. I moved to location 2 (power line circuit pin 10) and again did not get any voltage reading. I moved to location 3 (injector and dropping resistor pin 14, 15, 30, 31, 32, and 33) and did not get any voltage readings. Due to weather and lack of light I stopped the test here.

I will recheck again with a new location for a ground (used the metal tab on the floorboard after cleaning it, the door jam latch, and a bolt attached to the chassi) to verify if that was the issue. I also need to check the Air regulator to fuel pump reading. I do believe there could be an ignition switch issue which would explain the no voltage results or the main culprit is still that fusible link low voltage that feeds the ignition switch and fuse lock.

Now that I am saying this while typing it, it would make sense the 7v readings at the fusible links should be priority #1.

 

[steve240Z73]

Yes, the low voltage issue is one of the first things you should tackle. I believe Tony D said in the past that low voltage can damage the ECU.
You said you measured voltage on your links but never said what voltage you saw where. I'll also give you some other places to measure voltage to ground.
It also won't hurt to remove each link and look for corrosion on the fusible link block or the link itself.

Also take voltage measurements to ground at these locations:
1. At the white/red wire at the Battery post on the alternator
2. At the white/red wire at the ignition switch. You can unplug the wire harness from the back of the ignition switch to measure if need be.
3. At the white/red wire at the 6 pin connector (with 5 wires) under the driver's side of the dash (EFI power source)
4. At the white/red wire that feeds the headlight circuit at the combo switch.

That will help confirm voltage the voltage drops at the fusible links.

 

[ssfast99]

Yes, the low voltage issue is one of the first things you should tackle. I believe Tony D said in the past that low voltage can damage the ECU.
You said you measured voltage on your links but never said what voltage you saw where. I'll also give you some other places to measure voltage to ground.
It also won't hurt to remove each link and look for corrosion on the fusible link block or the link itself.

Also take voltage measurements to ground at these locations:
1. At the white/red wire at the Battery post on the alternator
2. At the white/red wire at the ignition switch. You can unplug the wire harness from the back of the ignition switch to measure if need be.
3. At the white/red wire at the 6 pin connector (with 5 wires) under the driver's side of the dash (EFI power source)
4. At the white/red wire that feeds the headlight circuit at the combo switch.

That will help confirm voltage the voltage drops at the fusible links.

Hello. The current battery voltage at this testing was 12.40v (haven’t charged battery for a few days). EFI fusible link 12.37 on both sides using battery negative for ground. Headlights 12.36 and 12.21 (rear taillights stuck on during this test, another gremlin). Ignition fusible link 8.25 and 8.26 (ignition key not in and in locked position). Fuse block 8.29 on both sides.

1) 11.90v

2) 12.35v

3) 8.37v

4) 8.36v

I’m seeing a pesky pattern here! I need to get full voltage in and out of those links

Update, battery is now 12.39v and all links at all connections are 12.37v. Some of my exterior lights are now working (could be broken bulbs but checking later) and radio came on. Getting 6.29v at green wire to fuel pump at service connection behind passenger seat.