CarShowz

car- nissan 240sx (single cam)
problem- all interior electronics not responding

I've recently changed my alternator and when I started the car again nothing inside came on. No speedo, rpm, temp, signal lights, radio, the auto seatbelts and the headlights work but they don't popup or return. All the fuses I've checked are not blown...radio, room lamp, electronics, headlight return etc...

What have I likely fried or shorted?
Thnx

CarShowz

Reading what I've found on da internetz so far this will be a long winded process It sux that it takes 2secs to ruin something then hours, days, weeks to fix it.

Please close thread if necessary unless anyone's interested in finding out what the prob was when I locate it

Computer_Nerd

100amp big ass fuse in fuse box located in engine bay.

CarShowz

hmm unless ur talkn bout one of the big ones without the clear top the largest fuse I see is the 75amp one for the alternator. I have followed the wiring harness from the POS battery terminal to the firewall n didnt' notice anything crispy or disconnected. The only electrical thing that's working is the ignition and the headlights. Everything in the fuse box by the driver kick panel is unresponsive but not one of those fuses are visibly blown.

I swapped out the alternator that was on for my old one from my blown motor hoping something would change and nothing. I pulled up the fuse box in the engine bay to see the bottom and nothing looks crispy there either. I have not pulled the one in the kick panel yet though. Am I just looking for the wrong things? I don't even hear my fuel pump priming or my antenna attempting to raise n I've been pickn at what I know n can think of for the last 6hours...no change

CarShowz

Is it possible that my ECU itself has shorted? Literally the only things electrical that are working are the headlights n starter. Everything on the list for the fuse box in the kick panel is "dead"..Though I figure if the ECU where completely gone the car wouldn't even start. This looks to be beyond what I can fix n it's time to turn her over to Nissan.

Fabrik8

If the ECU didn't have power, the engine would still crank without any issues. The ECU doesn't have anything to do with cranking, only running the engine. If everything in the kick panel fuse block is not working, I would assume that something between the battery/alternator and the kick panel fuse block is blown. I should be easy to find with a multimeter, because at each circuit in the (higher power) underhood fuse block will either work on not. So all you need to do is find out what has power and what doesn't, and track back from there. The electrical system is mostly like a tree, where the base is the battery (and/or alternator) and all of the other circuits branch out and then branch out from those branches. So if the branches don't have power, keep going down the trunk until you find power again.

250

Disclaimer: I've not messed with too many Nissans

Are there any fusible links in this vehicle? Most of the cars i've worked on have used a fusible link to isolate the primary Positive to each distribution panel. Unfortunately, these can be a pain to diagnose, because for the most part, the OUTSIDE of the wire looks okay, but the wire is burnt out inside. The only way to test one is to check for continuity, or to see if the link is "stretchy", indicating the wire is broken.

HTH

CarShowz

Thank you all for the input. I'll have a multimeter when my roomate gets home from work...I've gone through more shit with this car in the last 3months than I have in the 4years I've had it but I'd hate to give up now.

Fabrik8

Or, you could actually do troubleshooting instead of trying to diagnose electrical problems with your eyes.

CarShowz

Thanks everyone...I actually overlooked a fuse. The same 75AMP alternator fuse that I thought was good was actually blown. I replaced it and everything is back to normal.

Thanks again