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Infiniti G20 weird electrical issue is making is unsafe to drive

3 weeks ago my father (who died 2 weeks ago) gave me his 1991 Infiniti G20 which he has kept in great condition over the years with the last few being the exception. He’s the original owner and I have paperwork from every repair and service it’s had. Unfortunately the issue it has now started happening after he passed so I’m not going to get any help from him with info about how it’s been running the last couple years. Now to the good stuff.

When I got the car it was outside under a carport like always (lives near Seattle). I drove the car about 200 miles and then a couple days later I noticed the turn signal stopped working, but not only that there were several things not working. The turn signals (yet hazard lights work), the seat belt motor will not let it roll back across my chest, the blower won’t work but the AC and heat still works, the rear defogger stopped, the ABS stopped, and the warning lights and sounds for doors open and seat belts undone don’t work. Then while driving everything just “clicked” back on for about 5 minutes, then "clicked back off the rest of the drive. The next day I started the car, everything was fine but after waiting a couple minutes for the windows to get defogged everything shut off again. Driving around with foggy windows, no turn signals, and no seat belt across my chest is starting to scare me. Oh, and the problem can turn on and off without the engine on. If I just put the key into the “on” position it will sometime switch between working and not working.

I have unplugged and replugged the fuses and relays on the left side under the steering wheel, I’ve checked the voltage of the battery (2 years old with 7 year warranty and alternator was replaced 18 months ago) and it was about 12.4. I’ve tried reading the wiring diagram in the service manual without any luck figuring it out. When I took it to the Nissan dealership they did their scans and couldn’t recreate the issue and charged me $100 just for doing the electrical tests. I want this car to keep going since it has 174,000 miles and runs great (manual trans) so please help me figure out whats going on. It doesn’t seem like it’s a loose wire because the car doesn’t have to move for it to go back and forth between working and failing. It sometimes works more often if the car is kept in a garage but even then I’m not sure. At one point in the last year a couple mice got into the trunk but they have since left and I don’t see anything in the manual that says they could have effected anything all the way back there.

Please help. Thank you. I can take pictures of anything from the car, the manual, etc. so just let me know. I’m willing to do the work if you’re willing to help me figure it out.

I would focus on the Body Control Module–assuming that a car this old has one.

The switching on and off rules out fuses, but is consistent with a bad relay. A relay has contacts inside that can get corroded over the years. Replace any relay you can determine that involves the items you mentioned, which puts it is the same wiring circuit at some point.

Most car makers use the same part # relay in many applications, so buy a new relay and replace the OEM relays one at a time. When the problem goes away then you found the culprit (bad) replay.

Check the ground wire connections for corrosion. Bad grounds can do all kinds of silly things and older cars in wet environments easily develop bad grounds. Check the ground strap or wire to the engine block as well.

Check any exposed wires in the trunk for signs of being chewed.

For a $100, you think you’d at least get some advice on where to look next!

Do you have friends/family/acquaintances that could help you interpret the wiring diagram? Since there are multiple items that have failed, I would first look at the wiring diagram, starting at the items that flaked out and move backwards to see if there’s some common point where they all (or at least a lot of them) are powered, controlled, or grounded. These common points would be where to start part-swapping or checking/tightening connections.

I hate intermittent electrical problems. Even if when you have fixed the problem, you’re never completely sure because they are, well, intermittent.

Oh, and the problem can turn on and off without the engine on. If I just put the key into the "on" position it will sometime switch between working and not working.

Perhaps try wiggling the ignition key back and forth a bit when this happens. The key turns a lock cylinder that has a mechanical connection to the ignition switch. The ignition switch controls main power to a lot of systems…

Are the battery connections clean and tight. The ignition switch would be my first thought. All these systems are powered first through it.

The trouble you are having is most likely due to a bad wire connection, possibly in a multi-pin connector. The problem is most likely close by the fuse panel (or possibly with the fuse holder) in the dash or under the hood since you are having trouble with multiple things. The trouble could also be with the ACC contacts of the ignition switch. Using you service manual you should be able to figure out what main fuse, and dash fuse possibly, powers those items having trouble. There should be an overall diagram showing the fuses and places they tie to. To continue the circuit they sometimes use large letters to show you where the wire ties to further on. Like the letter A would also tie to another A further on in the diagram and there could be more point A’s also.

You should also purchase at least a test light probe to use so you can see where power is, or is not, getting to. To check the small fuses in the dash you can place the probe tip on the small contacts on top of the fuses, one for each side of the fuse element. A good fuse should power on both sides of the fuse if has power getting to it.

You may find just disconnecting and reconnecting connectors around the fuse panels may solve the trouble. Using a screwdriver handle to tap on suspected trouble spots can sometimes show up trouble like this.

Thanks everyone! was hoping someone has had this problem before but figured I’d get this sort of advice. Looks like it’s time to put on my Sherlock Holmes hat and start working my way through everything. I’ll look again at the wiring diagram and try and see if there are those places where it mentions connecting to other things (Like the letter A would also tie to another A further on). When I had to go trough the back seat to get into the trunk (another story) I kept my eye out for any signs of damage. I’ll start removing the linings in the trunk to see if there was any damage where I can’t see anything. Thanks again everyone and I’ll give an update once I figure anything out.

My daughter had a similar problem with a 94 Altima, Her dealer was also useless and charged her also. After talking to her, I told her to turn her key slightly to the left when it happened. That restored power to the circuits she had lost.

The spring in the ignition switch had gotten weak over the years and when she released the key after starting the spring didn’t return it fully to the on or run position.

Thanks everyone! was hoping someone has had this problem before but figured I'd get this sort of advice.

Where did you think my advice came from? It never ceases to amaze me. Someone will crawl through to the trunk looking for chewed wires but not try wiggling the ignition key…now there’s a second person suggesting the same thing. It’s actually a fairly common type of failure. It may not be your problem but couldn’t be easier to try and rule it out.

Gotta wonder why the dealer didn’t just suggest replacing the ignition switch?

I have seen more than one problem just by the steering wheel tilt being all the way up or down. Now my lucky guess, you got the car, changed the steering wheel tilt to all the way down, if right put it back in the middle and see what happens but agree with previous about ignition and key problems. Sometimes the tilt is enough to mess up connections.

Assuming this is not related to the ignition switch about all I can suggest (without having a wiring schematic available) is that you peruse your diagram to see if there is a common power source for the inoperative items.

You might also consider checking the inside of any fusible links that look like those in the link below. Sometimes with age and high current flow the solder can melt and create an on one minute/off the next situation. This may appear as a tiny ball of solder on one side or the other of the fusible wire inside the link.

I considered an ignition switch problem but those usually don’t cut in and out while driving.

This brings back memories of working on Chrysler products in the early 90’s. Instead of releasing the key when the engine started some people would rotate the ignition switch back from the crank position to a position between start and run. The engine will run but there is no power to the interior accessories and the airbag light remains on. Some claimed to have driven for up to an hour in 100 degree weather without air conditioning and inoperative power windows to get to the dealer due to this condition. To wiggle the ignition never occurs to some.

If you look for the trouble you are having in the trunk area you are going to waste your time there. The trouble is either in or near a fuse panel, or with the ignition switch. Wiring for the blower and other things like that don’t go to the trunk.