78 280z turns off with turn signal/reverse lights

[240260280]

get some electrical contact cleaner and spray every connector's pins (both sides) then make and break each connection 5 times and wiggle the connector while doing it.

[Usain_Boat]

59 minutes ago, 240260280 said:

get some electrical contact cleaner and spray every connector's pins (both sides) then make and break each connection 5 times and wiggle the connector while doing it.

So I cleaned them again with Deoxit and got some more connectors while I was at it too. The oil pressure connector hadn't been cleaned before and I know that is part of the fuel cutoff so maybe that will help.

[SteveJ]

4 hours ago, Usain_Boat said:

I got the front end on ramps and took a look at the reverse switch leads. The two female bullet connectors on the harness were very dirty so I cleaned them. One is continuous to ground and the other isn't. On the switch itself both male leads aren't continuous to ground. I'm not sure if it's advisable but I have continued removing the outer insulation on the harness to follow the reverse wires. 

Okay, this is a good start. If you have not already done so, download a copy of the FSM from this site. (If you are on a computer, the link is in my signature.) Also, look at Blue's tech tips for a copy of the full wiring diagram. I think there is even a color copy of the wiring diagram floating around this site somewhere.

On page BE-14 of the FSM, you'll find the reverse light circuit. The diagram shows that one side of the switch gets power from the fuse box, and the other goes to the taillights. Neither side should be grounded. Since you say one side of the switch is grounded, let's assume that is the side with the bulb sockets. Unplug both of your taillights at the taillight panel. Check the wire that had continuity with ground to see if it is still grounded. If it is not, the problem is at a taillight. That might also correspond to the dying problem happening with the turn signal.

If the wire is still grounded after that test, break the connection at connector C-4. Test again. If it is grounded, the problem exists between the switch and connector C-4. If it is not grounded, there is a chance the body wiring harness is damaged, probably by a screw and is grounding out. To trace the path of the body harness, look at the BE section of the FSM.

If my instructions don't make sense, send me a PM with your phone number. Sometimes I can explain this over the phone more easily than I can type it up.

 

[Usain_Boat]

I have the FSM and the color wiring diagram that I'm using currently. Just to get on the same page, as far as I know the wire that goes from the reverse switch to the reverse lights should be grounded since it just powers one of the bulbs leads and the other is grounded to the chassis. If not, what should it be/not be continuous to?

[SteveJ]

1 minute ago, Usain_Boat said:

I have the FSM and the color wiring diagram that I'm using currently. Just to get on the same page, as far as I know the wire that goes from the reverse switch to the reverse lights should be grounded since it just powers one of the bulbs leads and the other is grounded to the chassis. If not, what should it be/not be continuous to?

The wire that goes to the bulbs is not continuous to ground. The bulbs are the load (resistance). You should be reading about 3 Ohms resistance from the wire at the switch to ground. Only the negative side of the bulb socket should have continuity to ground.

[Usain_Boat]

@SteveJ Starting to test the reverse circuit for shorts and the hot side from the fuse box is now continuous to ground with a 21 Ohm resistance. The side to the reverse bulbs is continuous with about 1.3 Ohms resistance with the bulbs in and no continuity with them unplugged.

[Usain_Boat]

Ok so the 21 Ohms resistance to ground comes from the Yellow/Red stripe wire that goes to the seatbelt warning timer. Is this correct functionality? Nevermind, timer has 2.1 kOhms resistance to ground the 21 Ohms I was seeing is through the fuel gauge fuse as they share the same positive bus to the fuses.

Edited July 28, 2019 by Usain_Boat
Correcting information (Incorrect Resistances)

[Usain_Boat]

If I'm reading the wiring diagram correctly, the white with black stripe wire that turns on the fuel pump relay is the same that supplies power to the flasher fuse and fuel gauge fuse. So, given I don't have dash gauges/lights when the car won't turn on or turns itself off it should be a problem within those circuits. Also since I'm not blowing fuses, could it just be a bad connection in the white with black stripe wire supplying power to the reverse circuit being overloaded, then the relay for fuel turns off?

Edited July 28, 2019 by Usain_Boat
Made a sentence more clear

[Usain_Boat]

Digging deeper I do remember some splices in for the connections to the fusible link that I thought I fixed from the PO. When I got the car there were heat shrink crimps where the plastic was cracked and gone so I took them off and redid them. The fusible link in question (I believe it's the one closest to the engine in the front) has some green corrosion within the crimp and I also didn't get all the strands into the crimp. If I was to cut all of this out and redo it what gauge wire should it be? It looks heavier than the 14 gauge I have and is getting pretty short from whatever the PO did.

[siteunseen]

36 minutes ago, Usain_Boat said:

Digging deeper I do remember some splices in for the connections to the fusible link that I thought I fixed from the PO. When I got the car there were heat shrink crimps where the plastic was cracked and gone so I took them off and redid them. The fusible link in question (I believe it's the one closest to the engine in the front) has some green corrosion within the crimp and I also didn't get all the strands into the crimp. If I was to cut all of this out and redo it what gauge wire should it be? It looks heavier than the 14 gauge I have and is getting pretty short from whatever the PO did.

You should do the Cadillac upgrade that @wal280z came up with. 

I can't find on this phone but will with my lapdance.

 

[Patcon]

I like to solder connections when ever possible. Especially some where , like there, under the fusible links

[Usain_Boat]

2 minutes ago, Patcon said:

I like to solder connections when ever possible. Especially some where , like there, under the fusible links

How powerful of a soldering iron do you have? Using a 15w one I was struggling with 14 gauge