I have an 87 Max that lost electrical power to all systems in the car. This happened right after I was trying to jump the battery. Before that there was some power to all the systems - accessories, engine, lights etc. The fusible links, battery and batt terminals check out OK. Any ideas?

TIA

 

is the battry dead??? i dont understand what u mean

 

Before the jump the battery was at 9v - enough to power to turn on the radio, interior lights and gauges, but not enough to turn the motor over. After the jump the battery was at 11.5V, but everything is dead - no radio, gauges, lights or starter.

 

hope you didnt jump it backwards...

11.5V isnt enough either you need to get a new battery soon, undervolting everything can cause electrical damage, especially the computer

 

11.5 volts is enough to start. If I run my stereo for a while with the motor off I've dropped it down to 11 flat and still have been able to start the car. Keep in mind when car starts, volts should immediately jump to 13-14volts.

S

 

speaking of that, when i start my car there is no voltage increase till i hit 3000 rpm after that at idle its 13 14, im going to run 4ga strait from alt to +

 

Probably a sticking gauge.

S

 

na, (my remote start thinks the engine isent running if its not 13-14 volts) also i put the reverse gauges in, and now its stuck (something to fix) it hasent moved in a while.

 

The jump polarity was OK and the battery is brand new. Although there might have been some voltage spikes from a loose jumper cable. The car was not driven in about a 3 weeks, so there is a small current drain that kills the battery in that time. Is there a main circuit breaker, fuse or relay somewhere that could have blown? Is there a diagnosic I can run to test the computer ?

 

okay, a few things...

1. battery voltage doesn't determine if an engine will start, it's the actual amount of amps (CCAs) it can deliver. a battery can actually read 13 volts but not be able to supply the 400 CCAs it takes to start these engines. a voltmeter can read a state of charge on a battery with 12.2 being dead (0% charge) and 12.6 being full (100% charge) with every .2 volt step adding 25% charge to the battery. defined by BCI.

2. if the voltage was only 11.5 volts after you got the engine started, you've got a charging system problem.

3. "speaking of that, when i start my car there is no voltage increase till i hit 3000 rpm after that at idle its 13 14, im going to run 4ga strait from alt to +"

if the voltage suddenly jumps up to 13-14 volts when you rev it to 3000 RPMs, this is a specific problem with the alternator's field connector. it sounds like someone on this thread has this very problem. (quoted above.) there's a two-wire connector on the alternator. one is a thin wire that goes to the warning light on the dash, the other is the field wire. in order for an alternator to MAKE electricity, it needs to have some battery power coming IN initially to energize the electromagnetic field coil. that's what this wire is for. once the engine starts, the alternator makes electricity, and part of the electricity generated by the alternator gets recycled back to the field coil, and that initial input voltage isn't needed anymore. the voltage regulator now uses it to determine how much electricity it now needs to produce depending on battery voltage, etc. if this wire isn't connected, the alternator won't generate electricity on its own because there isn't any power coming in -- the power coming in is used to provide the electricity for the coils, and it's used by the voltage regulator to determine the electrical system's voltage, so that it can vary the output accordingly. with this power not coming in, the alternator doesn't make its own power until it hits a high RPM, where it "self excites" and will put out voltages in the high 14s as a voltage regulator default. this isn't fatally bad, but it shouldn't be allowed to continue.

it's fairly simple to diagnose a charging system problem. FIRST and FOREMOST, you need to start with a fully charged battery. don't try to jump-start the car. leave the battery on a plug-in slow charger overnight to charge it up full. once you've done that, it would help to get a digital multimeter that can be set to 20 VDC. get in the car, turn the ignition switch to ON, but don't turn it to start. all the red warning lights come on. MAKE SURE the red charge indicator light (first one on the strip, looks like a battery) is ON. if this light is not on, check that two-wire connector at the alternator. make sure the prongs are clean and not corroded. if that isn't the case, you probably need an alternator.

now start the engine. that charge indicator should shut OFF and the voltmeter on the dash should read at least 14 volts on a fully charged battery at idle. you shouldn't have to rev the engine first to bring the voltage up. if you have a digital voltmeter, read the voltage directly at the battery terminals. if it's any less than 13.2 or 13.3, you probably need an alternator. make sure the thick battery wire at the alternator is bolted tight, and the thin ground wires are good too. that alternator needs a good clean ground. make sure the belt is tight. make sure there isn't any oil or anything inside the alternator, since that isn't good for the brushes or commutator.

let us know how you make out.

Dan

 

YO thanks man, good write up, it makes sence now, im going to check this out, and def ground it better. im 50% sure its lear wire, but i dont recall any lights on when im driving, (i think the lights are mesed up anyway, when the washer fluid is low, the brake, gas and like 4 other lights come on)


ill tell ya how it goes

 

there is a funny thing about nissan and the way they wire their warning lights, and even on nissanforums.com, there's always confusion about alternators going bad and why the BRAKE light comes on when that happens. and they still wire them like this. anyway, in a nutshell, nissan has a bulb check feature that allows you to check the BRAKE warning light. it's wired using a relay into the charge indicator light. so that when you turn your ignition on and the charge indicator comes on, the brake light does too. just to let you know it works. nobody thinks anything of it. well then if there's an alternator problem, the charge indicator (battery) light comes on, and it kicks the BRAKE light on too. so I've read at least 12 or 15 posts about why both the alternator and brake warning lights come on at the same time with the engine running.

they do the same thing with the other warning lights that you don't normally see, just to have a bulb check. in my 88 sentra, there's a stop/tail lamp warning light. some of the 2nd gen maximas have it too. it comes on if you have a burned out light in back. that's wired the same way, into the alternator light, so that if there's an alternator problem, I'd be looking at 3 warning lights -- the alternator, brake, and stop/tail light. and just to confirm my theory, I disconnected the warning light harness at the alternator, grounded the wire, and I was right. it's the same thing with the SENSOR light a lot of nissans from the 80s had. I'm sure it's the same thing with the fuel, washer fluid, and other array of warning lights these maximas have. it's a good idea to have a bulb check, but it wasn't too smart to have them come on with the alternator warning light.

it isn't just nissan, cos toyota did it too. most other cars have a set of contacts in the ignition switch that are connected when you crank the engine. these contacts send power to the BRAKE light when you turn the key to start, so the light comes on for the few seconds you're starting the engine. GM and ford did that with the brake and temperature warning lights.

any nissan employees out there... can you explain this to me?

 

Looks like we are a bit OT with charging problems, although a good write up on this. I my case I would expect a 11.5 V charge to have more power than the 9 V, so I wouldn't expect everything to be dead at 11.5V when it wasn't at 9V. Any other info on dead electricals like a location of main relay or fuse?

 

werid, i have had 2 bad alternators and i havent ever haed the brake light come on except when one died completely while i was driving, but at the same time every light on the dash came on but my head lights and tail lights went out...it was at night...

the voltage regulator in the alternator was toast both times...one was defective from the remanufacturer but i have a life time warranty and got the 3rd for free and when it goes bad in about 20,000 miles (since they only seem to last about 30,000 miles) i'll get another free one...

if you havent figured it out....if you buy a new alternator GET THE LIFE TIME WARRANTY its usually worth the $15 or $20 more

 

most of the alternators are remanufactured. I don't know if "new" is actually any better.

I've seen some of the "reman" alternators and disassembled one for a GM. it came right off the shelf. sure, the regulator was new, but the brushes were worn down, never replaced, and the brush holder was cracked.

I guess it's pot luck though. one of my regular customers at auto zone had a '94 sentra limited edition. our first alternator lasted a little over a year. then I saw his sentra sitting in our parking lot for a few days cos it went bad. everyone thought the car was mine cos it's exactly like mine. well I warrantied it and helped him replace the alternator in the parking lot. two weeks later, he came back to get it tested cos the battery went dead on his wife while she was driving. I was getting weird readings from the battery, so I warrantied it and got him a new one. it was cold out, the battery wasn't fully charged, and I wanted to be sure it wasn't gonna leave anyone stranded again. that was the day before christmas eve. two weeks later, that alternator went bad and left his wife stranded again. he was so fed up he offered to sell the car to me for $600. I replaced the alternator and <knock on wood> haven't had any problems with it.

nice car, too. and now, the car is mine.