S13ORLANDO

Robert Fagan
‎91 s13 one side of 75 amp fusible link is shorted to ground. One side of fusible link has continuity to the positive terminal on the battery. The other side of the fusible link is shorted to ground. This wire goes to the positive lug on the alternator. Brand new lower harness, check good with FLUKE meter. The positive wire to the alternator is disconnected. It goes to ground as soon as I plug that rectangular plug (with the white grease). It looks like the cable goes over to that ACC RELAY on the drivers side. Yes I have the FSM. Am I wrong about one wire off the 75amp fusible going directly to the positive battery cable? The second wire on the 75 amp fusible going over to the drivers side relay box? DAMMIT MAN ..IF I HAD THE BUCKS..IT WOULD BE LS3 or BETTER !

S13ORLANDO

This was happening with the original lower harness too. Here is the original symptoms. Driving early morning second week of June. All gauge lights,radio,rear tail lights go out. Engine runs okay,headlights okay. Daylight later that day, the wires on the output of the alternator are burned up. I repaired them,discovered 75 amp fusible link blown. Long story short,blew same 75 amp fusible link. I got my trusty FLUKE and the FSM. I find a short to ground on the 75 amp. I begin to suspect my lower harness. I found a lower harness from FRSPORT. There is no way I 'm SMOKIN THAT LINK AGAIN!

I'm testing everything first. So before I plug in the alternator or anything else I am ohming out everything. I plug that one rectangular plug below the passenger side box for the fusible links.
. I am concentrating on that 75 amp fusible link. With the 75amp fuse out. One side ohms good to the positive side of the main battery. The other goes straight to ground once the cable is plugged. I looked at the bottom of the fusible link holder. I wanted to see if one of those two white wires was chaffing or broken insulation.

I followed the harness downstream..runs along the radiator and down into the drivers side box under the hood.

Help me with some LOGIC. They has to be a way to ISOLATE WHICH SEGMENT IS HOSED ? My worst fear is that this is a CHAFFED wire under a body panel or

REAR of the car. How do I BREAK this into SEGMENTS for TROUBLESHOOTING ? ?

S13ORLANDO

I went out and looked with my FLUKE again. With no lower harness connectors (no battery,no alternator). One side of the 75 amp fusible is shorted to chassis ground. I went over to the ACC RELAY on the drivers side. I pulled the Acc relay and no help.
I only wish I could SEGMENT this better logically. Does that SMJ JUNCTION under the dash have a disconnect ? Thanks Bob

godsmack

Just to sum it up. You're just going to have to pretty much trace everything. I know that ppl were having problems with just the altenator wire being the culprit and if that's where you had the burnt wires that's where your problem is. As far as it ohming out to chassis ground you're going to have that problem. In DC circuits current flows from a negative to a positive.

articwasteland

just a thought, but if your shorting where the wire leads into the fusebox, try removing individual fuses to track down where the short in the system is.
ie remove the headlight fuses and check if its still shorting, if it is, just replace and check another.
otherwise check the usual places for shorts like around the tires and the smj

S13ORLANDO

I LOVE MY FLUKE METER !With the "ROOM LAMP" FUSE IN and 75 AMP FUSEABLE LINK SHORTS straight to ground. With that fuse in place and no power we have a dead short.
I removed the ROOM LAMP FUSE and MR FLUKE says he is very HAPPY with
The 75 AMP FUSEABLE LINK circuit has INFINITE OHMS. I Know something is still HOSED ! That's where the FSM and my friend MR FLUKE will WIN !
thanks to FRSPORT for making the S13 KA24DE LOWER HARNESS available !
GRANDPA BOB

S13ORLANDO

No fuel. Engine turns over. I have lights on the exterior...back to checking fuses. Fluke and FSM . THANKS Bob

S13ORLANDO

OH YEAH.. I snipped the fuse wires on the FUEL PUMP RELAY..I was " grasping at straws " . FREE LANCING and disregarding the FSM. I PULLED THE FUEL PUMP RELAY. The contacts looked a little BURNT. SNIPPED one of the wires.

REPAIRED IT ! BACK ON TRACK ! .. PULLED MY HEAD OUTA MY BEHIND.
STICKING WITH FLUKE AND FSM.

WE are back to the original bug..."ROOM LAMP" FUSE OUT AND FUSABLE LINK 75 AMP FUSE IN....CAR STARTS..RUNS..OUTSIDE LIGHTS WORK. NO ALTERNATOR OUTPUT

PULL THE 75AMP FUSABLE LINK and INSERT the " ROOM LAMP " FUSE. THE POWER SIDE,OF THE FUSABLE LINK CIRCUIT IS SHORTED TO GROUND. I HAVE PULLED ANY AND ALL ACCESSORY ITEMS. RADIOS,AMPS,LED LIGHTS.

I WILL FIND OUT WHAT IS CAUSING THE "ROOM LAMP" circuit to short out !
NOW I'm down to checking all the interior lights and door switches.

I LOVE MY LITTLE 231,000 mile S13. I love being a '58 yr old 240sx driver !

S13ORLANDO

Hello,
With the 75 amp FUSABLE link pulled and the "ROOM LAMP" fuse installed DEAD SHORT to ground.

Tested everything with a FLUKE METER. The PLOT THICKENS ! This circuit goes DEAD SHORT ONLY WHEN THE HATCH DOOR IS OPENED.

Close the HATCH and INFINITE RESISTANCE !

Piece of CAKE...RIGHT.. I'll just look for the HATCH DOOR SWITCHS.

They probably look like the DRIVERS and PASSENGERS DOOR SWITCHES ?

I CAN'T FIND THEM PHYSICALLY IN THE HATCH DOOR OR CHASSIS. !

No problem, I will look in the FSM . NOPE CAN'T FIND THEM . PEARL HARBOURED AGAIN ! UGH ! HELP !

S13ORLANDO

I appreciate your input. The 75 AMP FUSIBLE link circuit is INFINITE OHMS when the hatch is closed. HATCH OPEN circuit goes straight to ground. If I have a bad alternator it's only BAD when the HATCH is opened . I am still looking for the HATCH LAMP ROOM SWITCH in the hatch. Thanks , Bob in Orlando.

racepar1

That switch is in the latch and I can absolutely assure you that it's not your problem. It would help out a LOT if you could be VERY clear on what your problem is. The problem you're describing above is not the same description as the problem you described in the OP.

S13ORLANDO

The problem is as I stated before . The 75 amp fusible link is dead shorted to ground when the 10 amp " ROOM LAMP" FUSE is inserted. I am using a FLUKE METER to the positive side of the fusible link. This is a NEW LOWER HARNESS from FRSPORT. It is installed properly so that the positive LUG on the alternator isn't shorted to the case.

The actual switch may not be the issue at all.I agree,but the short goes to INFINITE OHMS when the hatch is closed. The FUSIBLE LINK shorts to chassis ground with the hatch OPEN.

I don't want to ELIMINATE all of that wonderful wire near the HATCH ROOFLINE. I won't ELIMINATE any of the HATCH WIRING HARNESS either.

I WOULD CERTAINLY BE FOOLISH NOT TO INSPECT A MICRO SWITCH FIRST.

thank You,
Bob

racepar1

Have you inspected the wiring in the hatch/trunk area? It is much more likely that you've got a short in the wiring than the switch. Try removing fuses and un-plugging the suspected components, starting with the light. Your issue is nothing common and I can almost guarantee that the cause will be quite obvious once you find it. Honestly I HATE tracking down shorts, shit takes forever. Why don't you temporarily wire-in your own external switch in place of the OE one and see if it changes anything.

The 75a fuse is the main fuse for the alternator, which is why I suggested to try that. I've heard of that causing your problem before.

No worries man, it just seemed like you were rambling on a bit and it made it hard to really understand your problem.

S13ORLANDO

Thanks Racepar1...I read some of your posts. I see you meant no harm.
I replaced the 75 amp fusible link after it popped the one time. I have all the fuses out except the 10 amp “ROOM LAMP”.I suspect you are 100% right. The wiring in the "hatch harness" is my number one area of suspicion. That Hatch has opened and closed so many times. The car has spent every night in the garage since new.
I will fix this with my trusty JOHN FLUKE meter and the FSM. Thanks for your input.
Bob

racepar1

Check the wiring where it goes into the hatch through the rubber boots in the corners as well. Those wires ALWAYS break, I've seen it a million times. Usually the 3rd brake light and the rear defroster just stop working but it's completely possible, and probable, for there to be a short there. That would make sense since you say it doesn't short untill you open the hatch. Good luck man, it seems like you're on the right track.

PS: I get it, you've got a fluke DVOM. Jeez, take it easy! LOL!

S13ORLANDO

HELLO, RACEPAR1 and anybody else. FSM and FLUKE in hand. I just eliminated the HATCH LOCK INTERLOCK switch. I inserted a flat blade screwdriver into the HATCH LATCH MECHANISM. It's in my ROOM LAMP circuit and it varies 25 to 30 ohms open versus close.
The HATCH remained in the OPEN position. I tugged pretty hard on the HATCH WIRING HARNESS (left and right) and it didn't matter. When I moved or closed the HATCH we get INFINITE OHMS ! So Just looking at those HARNESSES at the ROOF LINE. Nothing jumps out right away. The obvious BUG would be a Chaffed wire up there. I have seen some photos where people tore the wires out. I saw pictures of a white electrical connector. It would be cool if I could unplug a cable in those HARNESSES ! We'll find this guys. I don't want to make a MESS out of these HATCH HARNESSES. They look pretty unforgiving . Thanks, Bob in Orlando.

S13ORLANDO

YES FAMILY and HOLIDAY PREPARATIONS FIRST. NISSAN REPAIR is way down there. LOoks like further inspection of HATCH SWITCH is needed. HATCH RAISED in air makes no difference on FLAKINESS of switch. THANKS.. 58 year old S13 DRIVER ! HAPPY THANKSGIVING ..GRANDPA BOB

S13ORLANDO

I hope to get on my GIANT ESCAPE II first to loose a fell pounds. Then off to fix the S13 ! I am so close. Happy Holidays Bob

S13ORLANDO

Hello, HAPPY HOLIDAYS...I have all the fuses (ROOM LAMP) and the 75 amp FUSABLE link all working. I drove it to ADVANCE AUTO PARTS. Their tester said my alternator /charging circuit has failed. The next step is to pull the alternator and let them "bench test" it. I have not removed the alternator from an s13. I can at least see it. Thanks. Bob

S13ORLANDO

I removed the OEM original alternator. I brought it to ADVANCE AUTO PARTS to test on their " BENCH". The DENSO unit passed all tests. The counter guy said the bearing were quieter than most new alternators. I will test the fuses and fuseable link again. Wow I can see 2013 on the horizon !

Darfin

We must have the conclusion. I'm having an eerily similar problem.

NukeKS14

dude hasn't been on the forums in 5 years. This thread is 8 years old....

Darfin

Yeah I was speaking ironically, was kinda sad to see an end to his detailed updates before a conclusion haha.