SleeperZ31 Posted April 12, 2008 Share Posted April 12, 2008 Okay i was driving home tonight and i noticed upon startup that the battery "idiot light" was dimly lit, but seeing that the car was running normal i started on my way, then to my suprise all of the dash warning lights except the "sensor" light came on! the lights slowly come on when im running above 2,100-2,300 rpms or when im at or above 55mph, below that they turn off...what could cause this? i didnt notice anything strange other than a slightly high idle at around 1,200rpms even with all accesories off and the headlamps off too... Is my cars ecu trying to warn me of some impending catastrophe or is this just a fluke? seriously, this is the only thing my '87zx has done wrong in almost a solid year of ownership. Help please! Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted April 12, 2008 Administrators Share Posted April 12, 2008 Okay i was driving home tonight and i noticed upon startup that the battery "idiot light" was dimly lit, Disclaimer- I've never touched wrench nor DVM to any Z31, but I'll take a stab... The battery idiot light has no likely connection to the ECU. It very well may be reflecting a charge problem. ...then to my suprise all of the dash warning lights except the "sensor" light came on! What is a "sensor light"? ...the lights slowly come on when im running above 2,100-2,300 rpms or when im at or above 55mph, below that they turn off...what could cause this? With the above info, the first thing I'd be looking into is the charging system. Do you have a voltmeter? What does it say? Quote Link to comment Share on other sites More sharing options...
DuoWing Posted April 12, 2008 Share Posted April 12, 2008 This is weird, because something very similar happened to me very recently. It could be a coincidence in the way that it went away. I have an 83' 280ZXT, but I'm running the ECU/MAF combination from an 84' Z31T, which would be wired up very similarly to your 87. Anyway for a while my idiot lights would all start lighting up, after a while it stopped. Then a month or two later it seemed like the issue came back with a vengeance. Anyway I would start the car and it would idle real low and my idiot lights would be off, the second I revved it, turned the headlights on or basically did anything the dash would light up with all the idiot lights coming on. I thought it was my charging system, but it didn't seem to have any problems running everything and my car would still continue to start up fine. I was clued in by a fellow Z driver that in the 280ZXT harness there was a crimp connector that Nissan had put in which had a tendency to go bad and cause grounding issues. I had driving issues where when I'd shake the wiring harness it would run better. Anyway I cut out the crimp, stripped the wires down, and made a newer, better connection for these grounds. After that my idiot lights stopped coming on. They haven't come on sense, it's been a few days now, but still. It could just be a weird coincidence though. Also before I fixed the connection I was driving the car around in the daytime with everything off to see if it was a charging issue or something and it was doing the same thing, idiot lights were off while idling, but once I got above 1000 or so RPM they all came on, then would go off while idling. This crimp if it exists on the Z31 Harness would be I'm guessing on your top ECU plug, as the way the Z31 ECU sits in my 280ZX is basically upside down, or the plug closest to the little hole on the side to see the red/green leds. There were two black wires coming out of my ECU that ran into a electrical taped part, then split out into 3 wires. Again this may just be a coincidence, but it seems weird that our problems are very similar and mine stopped right after I fixed this. Quote Link to comment Share on other sites More sharing options...
SleeperZ31 Posted April 13, 2008 Author Share Posted April 13, 2008 well i do know now that my electric cooling fans been running too much, wearing out the brand new alternator and then draining the battery, since it died on me as i pulled into my housing area, ill fix that tommorrow by raising the temp that the fan comes on and getting a better battery, but it still doesnt explain the idiot lights coming on.. oh and the "sensor light" is the idiot light furthest to the left in the 87' 300zx's guage cluster. Quote Link to comment Share on other sites More sharing options...
DuoWing Posted April 13, 2008 Share Posted April 13, 2008 Well apparently, it was just a coincidence as the issue came back today. Quote Link to comment Share on other sites More sharing options...
xenonxiii Posted April 13, 2008 Share Posted April 13, 2008 When the alternator goes out it can cause all kinds of strange things to happen on the Z31. The most common one being the dash lights coming on. Quote Link to comment Share on other sites More sharing options...
nick.mitchell69 Posted April 13, 2008 Share Posted April 13, 2008 Try replacing the regulator,its a little black box screwed onto the back of the alternator with 2 wires plugged into it.Mine wore out,idiot lights occasionally came on when turning sharply and when first started on idle.Actually started overcharging my battery to just over 14volts,changed the regulator and problem was solved.Give it a go,they dirt cheap so not much to loose...it might save having to replace alternator... Quote Link to comment Share on other sites More sharing options...
danny240zturbo Posted May 24, 2008 Share Posted May 24, 2008 hi , your problem is the alternator , when the alternator doesn't charge enough anymore all lights will start to glow slowly and later everything is going to shine bright because there isn't enough volts and the car starts to act very strange and finally it wil refuse to start. this is very normal , just change the alternator and all is ok again danny z club belgium Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted June 19, 2008 Share Posted June 19, 2008 Is this a symptom or the problem..........have they been separated? If not, check the ground between the negative battery terminal and the body. (it's right there next to the battery) Most likely an alternator but you might want to see if a lifted ground is causing your symptoms or whether it has caused the alternator to charge it's little heart out and killed itself. Quote Link to comment Share on other sites More sharing options...
Guest mwolvin Posted July 10, 2008 Share Posted July 10, 2008 FYI-- the "sensor" light you are describing is a mileage based light set to trigger at (if I remember correctly) 30,000 MI and 60,000 MI. If your car has more miles than that, then it is unplugged. It's a reminder light to change some emissions component. Quote Link to comment Share on other sites More sharing options...
D15T0RT10N Posted July 15, 2008 Share Posted July 15, 2008 FYI-- the "sensor" light you are describing is a mileage based light set to trigger at (if I remember correctly) 30,000 MI and 60,000 MI. If your car has more miles than that, then it is unplugged. It's a reminder light to change some emissions component. It's 90,000 that you unplug it for good. Hilariously enough, the PO of my 87 found it necessary to yank out the dash and remove the light bulb I can't believe he didn't see the "Sensor light, unplug after 90,000 miles" tag dangling after he removed the drivers knee panel. The actuator that controls the sensor light is stationed inside the dash, near the glove box. Resetting it is as easy as pushing a button, just in case you would like for the car to pester you every 30,000 miles to check the O2 sensor. (though I have no idea if it will still do it's thing beyond 90,000, I don't see why it wouldn't. ) I think the dash light bug has more to do with dirty A/C current leaking than it does low voltage. (save for the actual batt light, which I have NEVER seen when my batt was low) There are diodes in the circuit that decides to switch the lights on, and the A/C current can have a weird effect on diodes. When my alt went, the dash lights seemed to enjoy flickering when I first started the car, which was accompanied by VERY rough idle, which cleared as soon as the lights stopped flickering, as the alternator cleaned up it's act when warm. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted July 16, 2008 Share Posted July 16, 2008 First thing to check is if you have bad body ground. Quote Link to comment Share on other sites More sharing options...
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