No power to interior/dash

[tristan582]

So my problem is that my power windows, tachometer, speedometer, odometer temperature gauge and blower motor all stopped working when i started my car Saturday night. Checked all fuses even the ones in engine bay and they were all clean and not popped. I checked to see if car was charging which it was. 14.2V when car is running. Battery is less than a year old. (Optima Red top). Not sure what else I should be checking. If a relay related to this were to go is there anyway of checking it? I assume with a voltmeter and checking for resistance. But not sure on this process. Car worked on a 750 mile road trip just last week and then this Saturday it just decides to stop. Car runs and drives just fine. Another note the gas gauge is working. Car is a 92 240sx. Almost completely stock other than an intake. Thank you everyone. Any more question please let me know and il try to answer as quick as possible.

[Rayne]

The factory service manual has the processes you need to diagnose most of the common 240sx problems.

[pacotaco345]

My car did that and it was the little ground wire on the alternator was loose causing me to blow the 75A fuseable link in the engine bay...

[tristan582]

so i checked the fusuable link in engine bay and all of them are good even the alternator one. I have been looking in the manufacturer book and can't seem to find a fuse or relay that would control all of these units

[Vegass13]

Is your car lowered at all? Maybe rubbed through some wires on the harness

[Vegass13]

And I don't think there are relays for the cluster

[Smallblock]

Going through this right now. Googled and it looks like there are 3 common reasons this could occur.

1. The TCU is fried, little white box next to the interior fuse block. Here is the write-up.

http://www.nicoclub.com/archives/fix-for-240sx-instrument-paneldash-lights.html

^This one seems pretty common^

2. There is a wiring problem somewhere such as an internal problem with the headlight switch (corrosion, loose connections), the stereo wiring is also common especially if you've had an aftermarket deck installed and the harness has been cut/spliced, which could both potentially cause the TCU to blow as well.

^This is probably least common^

3. The 3rd is the worst as it seems its fairly common for wiring to fray or break which causes lots of problems. Most common on lowered cars is the harness that runs under the drivers front fender makes contact and the insulation is rubbed through causing grounding and contact between wires. Another problematic area is behind the interior fuse block.

^This is what I am dealing with at the moment. After testing and tracing, found out the TCU is shorted, so jumpered the circuit as the fix on NICO talks about, now there is proper power there but still nothing works. Pulled all fuses(they tested fine with a multimeter) and discovered that someone tried to ghetto fix as every single fuse in the interior block had been jumpered with a strand of copper wire wrapped around the legs, fixed that nonsense and immediately 3 fuses blew, can't remember right now which ones. After more tracing came to the conclusion that the Red with Blue stripe wire (FSM lists as R/L or red and lavender), which is a power wire for quite a few items mainly interior and lighting related, is grounding out somewhere between the TCU and the headlight switch. The reason this could be the cause of all the problems is because that wire is connected in one way or another with pretty much all of those circuits(running lights, dash lights, interior lighting, wiper motor etc even if just through the TCU), so if its grounding in one spot its pretty much grounding power for everyone of those circuits simultaneously. I haven't confirmed or fixed yet because as far as I can tell I need to pull the dash to access the entirety of that section of harness (but from testing and tracing wiring I am pretty confident this is where the problem is) but as soon as I do I'll post pictures of where its broken and if the repair fixed the problem.

There's a lot of info on other forums as well, so in this case Google is very much your friend and is a good place to get ideas on where to start looking and what to do

Good Luck

[tristan582]

Going through this right now. Googled and it looks like there are 3 common reasons this could occur.

1. The TCU is fried, little white box next to the interior fuse block. Here is the write-up.

http://www.nicoclub.com/archives/fix-for-240sx-instrument-paneldash-lights.html

^This one seems pretty common^

2. There is a wiring problem somewhere such as an internal problem with the headlight switch (corrosion, loose connections), the stereo wiring is also common especially if you've had an aftermarket deck installed and the harness has been cut/spliced, which could both potentially cause the TCU to blow as well.

^This is probably least common^

3. The 3rd is the worst as it seems its fairly common for wiring to fray or break which causes lots of problems. Most common on lowered cars is the harness that runs under the drivers front fender makes contact and the insulation is rubbed through causing grounding and contact between wires. Another problematic area is behind the interior fuse block.

^This is what I am dealing with at the moment. After testing and tracing, found out the TCU is shorted, so jumpered the circuit as the fix on NICO talks about, now there is proper power there but still nothing works. Pulled all fuses(they tested fine with a multimeter) and discovered that someone tried to ghetto fix as every single fuse in the interior block had been jumpered with a strand of copper wire wrapped around the legs, fixed that nonsense and immediately 3 fuses blew, can't remember right now which ones. After more tracing came to the conclusion that the Red with Blue stripe wire (FSM lists as R/L or red and lavender), which is a power wire for quite a few items mainly interior and lighting related, is grounding out somewhere between the TCU and the headlight switch. The reason this could be the cause of all the problems is because that wire is connected in one way or another with pretty much all of those circuits(running lights, dash lights, interior lighting, wiper motor etc even if just through the TCU), so if its grounding in one spot its pretty much grounding power for everyone of those circuits simultaneously. I haven't confirmed or fixed yet because as far as I can tell I need to pull the dash to access the entirety of that section of harness (but from testing and tracing wiring I am pretty confident this is where the problem is) but as soon as I do I'll post pictures of where its broken and if the repair fixed the problem.

There's a lot of info on other forums as well, so in this case Google is very much your friend and is a good place to get ideas on where to start looking and what to do

Good Luck

Cool man thank you for the reply. I went through my stereo wiring and made sure it was good. Remade a ground as it was grounding through the antenna. I guess next is to check those other things. Yes my car is lowered. Quite low. I will go look at the driver fender and then dig behind fuse box. Man car goes fine for a 800 mile road trip no problems then this lol. Thanks guys and i'l update when i can.

[ZX88]

tcu is probably the culprate. you could also check the acc relay behind the fuse pannel just to be safe.

[tristan582]

Even if I have a normal dash and not a hud there will be a tcu?

[ZX88]

Even if I have a normal dash and not a hud there will be a tcu?

yes i think its the same.