So- I'm driving down I95 in my little old truck and it keeps doing more and more strange things... So, I'm hoping you all can help me diagnose the problem.

A/S/L: 94/4 banger Nissan Pickup/about 1.5 hrs away on I95

Symptoms:
-constant high pitched whine
- whine being amplified through speakers (relative to rpms and shifting) when radio will remain powered
- radio cutting on and off frequently
-no longer reading rpms above 1.75
-keeps dying in bumper to bumper traffic
- clock keeps resetting itself
- ac keeps kicking in and out

I'm thinking bad/loose connection somewhere, alternator going bad, something along those lines...

Temp seems ok, and it seems like it'll be fine if I ever get out of this traffic... The first time it happened a few hours ago I checked the connections and it went away for just over an hour but when I rechecked and made sure everything was ok it had no affect.

7/28/2008 4:28:36 PM

Very first thing I would look at would be the battery terminals, specifically the positive cable and all the power taps coming off of it. Make sure all the connections are clean and good.

Next, check your alternator charging voltage. Should remain between 13.2 and 14 volts, maybe 14.5 TOPS. If you have an internal regulator failure or a bad diode, then you might get the same symptoms.

7/28/2008 4:41:49 PM

i agree, but check the big fuses under the hood too.

7/28/2008 4:51:20 PM

main power supply wire(s) that feeds the fusebox(es) or one of its connections.

could possibly be a common ground area also depending on how it's wired, i haven't messed with those years much, just a handful of the older 720's and hardbodys.

i'm guessing your home by now or close to it, but if you need anything just holler and i'll come with the trailer.

[Edited on July 28, 2008 at 7:33 PM. Reason : .]

7/28/2008 7:30:44 PM

sounds like your ground between the engine block and the frame, due to the radio noise, gauge problems, etc, try running a ground from your battery directly to the engine block, otherwise, check all your power distribution wires, ie battery to starter, grounds, and battery or starter to fuse block

it may be the alternator, but usually when one shorts that bad, it either locks up or melts the fusible link

[Edited on July 28, 2008 at 8:38 PM. Reason : gimme a holler if you need diagrams, i still have alldata]

7/28/2008 8:37:41 PM

^You get a lot of radio feedback when a diode shorts. It will also drain the battery when it's shut off and voltage spikes can cause funky gage behavior or intermittent operation of accessories.

The nissans are bad for developing this kinda problem when the power taps on the positive battery terminal degrade from corrosion...especially the hardbodys. But the alternator can and will develop that kinda noise when it shits the bed. It's a Hitachi alternator, or should be. I've had 4 Nissans that have had numerous issues similar to these. on my '84 Sentra, it was as simple as a loose positive battery cable. On my Maxima, it was the power taps coming off the positive cable. My '86 Trooper had similar problems (yes I know it's an Isuzu). When the alternator on the Sentra shit the bed, it behaved similarly, and killed the battery when I shut it off (diode breakdown). My ACK! Integra just killed the battery when there was a short in the armature windings...cause by my washing the engine and alternator, which were covered with lots of clayey soil (the variety of which contained lots of 2-1 expansive clay minerology which has a very high cation exchange capacity).

An alternator is a beautiful thing when it functions correctly. But when they don't...

7/28/2008 10:19:29 PM

alright Dr. Dirt

Quote :

"the variety of which contained lots of 2-1 expansive clay minerology which has a very high cation exchange capacity"

7/28/2008 10:24:28 PM

Why do you think they call me Dirty Dan?

7/28/2008 11:05:27 PM

Thanks guys-- I really appreciate all the ideas. I stopped and did a bit more fiddling and made it home without too many more problems. Unfortunately, I got caught up in some time sensitive stuff, so I'll have to do my real investigation in the AM. I guess the truck's finally gotten ticked at me for driving it >500 miles per weekend for the last 1.5 months

7/28/2008 11:39:16 PM

^^it sure as hell doesn't have anything to do with dirt.

7/29/2008 1:40:42 AM

Quote :

"Why do you think they call me Dirty Dan?"

because it sounds better than dookie dan?

7/29/2008 8:05:15 AM