Alright lets get one thing out of the way...I'm a mechanic and work in a shop with a bunch of other smart gearheads but simply can't figure this problem out. My ABS light, brake light, and battery light have been on for about 2 months. The car runs and drives great with no symptoms of a charging problem, etc... I tested my charging system at work and determined the alternator was bad (excessive ripple and charging at nearly 16 volts). I changed the alternator but all the lights on the dash still remain, and what is odd is if you unplug the wiring harness from the alternator the brake and battery lights turn off (but they should still stay on to indicate a charging problem) and they only come back on when you plug the harness back in. The ABS, however, still stays on in either case. I drew the code for the ABS and it came up as a code #61 (actuator motor). I know the motor itself is fine because I have felt it kick in a few times during our new england storms while the light has been on, and all fuses for the ABS are fine. I haven't had the chance to check any relays and additional harnesses yet for the ABS, but wanted to see if anybody had any thoughts as to what could be causing these very odd symptoms. When I turn the car on all 3 lights come on at the same exact time, which tells me that all 3 are likely caused by the same problem. But having the brake and battery light go out when I unplug the alternator is really bothering me. Me and all the other mechanics in my shop are completely baffled and I have gone from loving my car to absolutely hating it. Any thoughts/suggestions for further troubleshooting this problem would be greatly appreciated. Thanks!

 

sounds like a frustrating problem. I've never heard of this happening but I'd start off by unplugging the battery for a little while. If that doesnt work and since you're a mechanic you can try hooking up a replacement ECU- like from one of your customer's cars.

Whats the voltage with the motor on and your new alternator?

 

Where did you get the replacement alternator?


Have you tried to reset the ABS light to see if that stays off.. i.e maybe it was a one-time failure with the actuator...

Typically your symptoms indicate a bad alternator... perhaps you got a bad reman?

 

What's odd is it's not a remanufactured alternator. It's a brand new alternator (NSA)...you can get them from rockauto.com, etc... Charging voltage is dead on right at 14 volts and the whole charging system tests fine. Battery is good, starter is good, alternator is good. What confuses me is that if it's just a problem with the ABS the battery and brake light shouldn't be on. However all 3 lights come on at the same exact time upon starting the car which tells me that they all must be related to one single problem. I'm going to fool around with it more tomorrow (hopefully it's a slow day). I think I'm going to concentrate more on the ABS issue for now since the charging system is good, then if fixing the ABS problem happens to get rid of the brake light and battery light too then great, if not then I'll have more homework to do. In the meantime if anybody thinks of anything else pleeeeeeease let me know. Thanks

 

There is a diode (E121) between the ABS warning light and the ABS Solenoid Valve Relay (E79, engine bay right side fuse box). It is located on the driver side underdash close to the door. Check and make sure this diode is ok. If this diode is shorted, the warning light will be always on.

 

He says when he disconnects the alternator the lights go away. I really think its a bad alternator. Even if it charges it's giving off some kinda voodoo signal.

Try another alternator and I think your problem will go away. They just dont make them like they used to

 

This Gen Maxima's are known to have wire shorts/cracks in the harness right by the sharp bend correct?

Maybe this is your issue...when you disconnect the harness from the altenator side the lights go away....just makes me think. A look into the condition of the wires in the harness might be worth a try. Maybe there is a short some where which is causing this but when you disconnect the harness from the alternator side the power to the shorted wire is interupted and the lights go away....just a educated guess.

-Ken

 

I agree with kenju4u it sounds like it could be a short in that wire harness/wires. If you can try see what the signal response is right before the wires connect to the ECU (I'm assuming they would I could be wrong). It's probably giving the ECU a reading 0 volts instead of 14 volts. Being your a mechanic I'll assume you have some type of FSM for the car and look up the wiring diagram (cuz I don't feel like it right now)

 

Thanks guys, I'm going to address all these issues tomorrow. First starting with the ABS diode per SVI30s suggestion. I should have thought of that before because we replace them in Escorts ALL the time, plus it is linked to both the ABS and charging system which would cause all 3 lights to come on at the same time because if it's not supressing the voltage fully, or not even allowing any current through the circuit, it would not only trip the ABS but the battery and brake light as well. I was going over the schematic today and it seemed like it was the only thing that would cause the symptoms I'm having. I'll be sure to post my findings tomorrow. Thanks for all the help

 

That light is normally turned on by the ABS controller which pulls the light wire to ground. The diode connects this wire to the normally closed relay but in reverse bias (open). If the relay opened for some reason, then the diode turns on the light as a warning that the ABS actuator is no longer working.

If the diode is shorted (like by high voltage), then the light have a ground path thru the relay and will be always on.

May be some other problem but this is worth a look. Just disconnecting it will show if it is shorted.

 

i had this problem the otehr day, i had a lot of corrosion on my battery terminals n all 3 light came on. I claened it off n the alternator re-charged teh abttery n then it was fine afterwards. Did you try to put a new battery in?? since hte alternator was going bad, it prob drained alot of juice from the battery itself. i would change the battery n see if it helps. it should fix the problem, and also, when the three lights came on, my audio system did not work. if your audio doesn't work, i would chagne the battery. somehow nissan has a safety feature for turning off the radio to try to save some battery life. i have an i30, but it should be the same thing

 

That's a fine lookin I30 you have there. Thanks for the suggestion as well. My battery terminals are fine though and even though my battery was drained completely I threw the battery charger on it and it's holding it's charge and cranking at 630CCA, so the battery is good. These lights came on when my old alternator was actually overcharging (which is why I changed the alternator in the first place). It was charging at nearly 16 volts! Whatever it is it has to be a wiring problem. I brought my test light and multimeter and a few other items home this weekend from work so I'm going to toy with it tomorrow. If I don't find anything else that makes me suspicious then I'm going to order the E121 diode and replace that to see if it fixes the problem. Thanks!

 

Don't buy the diode yet. Just disconnect it to see it the light goes out. If it does, then change the diode.

 

thanks I will do that. Also...if the ABS is throwing a code for the actuator motor (code #61) can it still be the diode? I believe it can be and just be causing it to throw a false code because the actuator motor works since I have felt the ABS kick in. I guess you never know til you try at least. Tomorrow im not doing anything before 1:00pm then I have a brake job ona big GMC pickup i'm doing on the side so I will tacke this in the morning. Thanks

 

There is a code 61 diag procedure in the FSM BR section around BR-50. Since you know it is working, look for low 12V and/or poor ground. You are in an area of potential corrosion damage.

 

Thanks I'm aware of that. I have been checking out relays, fuses, harnesses and wiring for corrosion, etc... So far haven't found anything. I did find a blown ABS fuse in the fuse box on the driver's side of the engine bay. Replaced that but all lights still remain on. All fuses elsewhere including the 30A fusible link for the ABS are good. So far all the harnesses I have checked out appear to be fine, no corrosion or anything. What is also odd is my car normally isn't garaged but it was garaged roughly 2 months ago so this happened while it was protected from the elements. This leads me to believe that it likely isn't corrosion, but it still never hurts to check. I'm placing my money on the diode since it appears to be the only thing that can cause the ABS plus the brake and battery lights to be on. Hopefully I'll have everything figured out tomorrow or early into the week. I'll post back my findings once I do some more tinkering with it

 

youre the machanic my man,, lauch the computer to ur max, reset codes, reset ecu... actually my abs light was on. i reset the comp, was off right away.

 

well to test the diode isn't hard. Take it out, with ur multimeter, since it is operated by a lil battery, you should nly be able to read a voltage one way. Since the diode is forward biased, when reversing it, no voltage should be detected. I'm sure you know that already. Otherwise i got nothing else really....sorry dude!

 

Well I already pulled codes and such. Like I said before I pulled a code 61 for the actuator motor for the ABS. Therefore something is wrong, and resetting the ECU is only going to temporarily mask the problem. The codes are more than likely going to come back, though if all else fails and I can't find anything wrong I will clear everything just to see if for some reason the lights don't come back on (which would be nice, lol).

ImmaSquash - Thanks I know how to test the diode. It's just a matter of finding time to pull the gauge cluster out to get to it. Probably tomorrow...I just did brakes on a friend's truck and now it's raining outside and I'm not working in the nasty weather. The Max is running mint, and that's my main concern But those lights definetely **** me off, haha

 

From the looks of it, this diode is mounted just off the main vertical wire bundle above the left side kick panel. It is on the Engine Room "E" bundle and not on the interior wiring Main Harness "M" bundle. Should be not that far from the firewall rubber gromet.

 

Didn't have a chance to check the diode yet. But what do you know today it was snowing/sleeting so I purposely locked the wheels up to see of ABS would kick in. NOTHING...therefore it's definitely the actuator motor prob (just like the code...61). I'm hoping it's just the relay and not the motor itself because that thing is crazy expensive. Still doesn't explain the brake and battery lights though...so maybe it's the motor/relay AND the diode. Time will tell...looks like it's going to be a very slow day at work tomorrow

 

Dont be so quick to blame the motor. It could be something as little as one sensor being disconnected. There is a procedure to read codes from the ABS system. If you have someone with a CONSULT computer get it scanned. If not, it might be worth the 50 bucks at the dealer to find the correct cause.

 

Sorry if you misunderstood, I'm a mechanic myself and I'm not blaming the motor right away. The code, however, is for the motor or the relay, so I know it's going to be something preventing the motor from getting power (that is if the motor isn't shot). First thing is to make sure no salt/sand has made its way into any of the harnesses, though I have checked most at this point. I'm going to test the relays and such tomorrow then take things from there. We don't have a CONSULT computer where I work but we have high-end Snap-on diagnostic equipment which are more than sufficient. This is one of those issues that's going to take time and patience to pinpoint though.

 

This relay switches GND. So if the relay is bad, the light will be on also.

 

The other day I drew power right from the battery to the motor (bypassing the relay) and the motor turns so at least I now know the motor is good. I'm going to pickup a relay from Nissan probably on Monday and pop it in since it seems that's the only thing at this point that could be preventing the motor from receiving power. However I'm still puzzled by the brake and battery lights being on unless they're on as well since the relay is part of the electrical system and therefore will trigger those lights plus the ABS. Relay is cheap though so I'm just going to get one and see how things go

 

Did the relay helped?

 

Dealer didn't have the relay in stock so I won't have it for a few days. Can't believe that little bugger cost me $29 and that's wholesale pricing since I bought it through the shop. I'm hoping for that kind of cash that it fixes the problem. I'll let you know