channoff

I have a 2002 Maxima with all three of these lights on. So, I did a thorough search here and ran the self diagnostic by grounding PIN 9, thinking I would get the code for a problematic wheel/ABS sensor. Instead, I received code 71 - Control Unit BR-72.

I have no idea which control unit that is. Can anyone assist me in troubleshooting???

EDIT: Couple other things to add about this issue:
1) This only happens when ambient air temperature is below 60 degrees and engine is cold. Once engine has warmed up, I can restart engine and all the lights go off

2) Speedometer doesn't work when lights are on and goes away when lights are all off

03VQMAX

iTrader: (46)

The control unit is possible the ABS unit, it's on the drivers side near the master cylinder.

foodmanry

iTrader: (15)

Wait a minute...isn't this also indicative of a bad or failing alternator?

channoff

I thought alternator failing was ER brake light not turning off due to it being wired directly to alternato

DjHackStyle

+1

channoff

So, I believe I located the ABS Control Unit under master cylinder and intake. Does that sound about right?

Anyone know how hard this is to replace?

DennisMik

iTrader: (2)

It sounds like you found the ABS control unit. But to back up to your original post, you had code 71. The BR-72 is the FSM section and page number to look at for troubleshooting. Section BR is Brakes. Page 72 has the diagnostics for code 71. Did you try this?

2damax

+2

DennisMik

iTrader: (2)

Bad alternator turns on the brake and battery light.

channoff

Thanks. I am looking at the FSM and BR-71 puts me in the middle of a procedure which seems odd. Any idea where the ABS actuator is located?

The thing I find most odd about this particular issue is that it only happens on a cold engine when the outside air temperature is below 60 degrees. Even on a frigid day, once the engine is warm, I can just restart the car and it goes away until I have a cold engine again.

I am considering selling this car as is without fixing this. After repairing MAF, replacing struts, brakes, alternator, etc all by myself, I am really tired of keeping up with this car.

DennisMik

iTrader: (2)

OK, I goofed a bit. I was looking at the 2001 FSM, so if you have any other year manual, you will not be looking at the same thing I was. Sorry. I wish all years of the FSM were paginated the same.

The reason I use the 2001 FSM for this is that it has the most information on ABS and even then it is kind of pathetic. Get the 2001 FSM BR section from here and you can follow it.

http://boredmder.com/FSMs/Nissan/Maxima/2001

Basically, the diagnostic procedure has you check that the ABS control unit is grounded via pin 16 of the connector. Then you check for 12 volts on pin 17 of the control unit when the ignition switch is on. If those 2 pins check OK, then the control unit is bad.

The control unit is on the top of the ABS assembly that is under the master cylinder. What I am not sure of is where the electrical connector is to do these tests. I can't see it from the top. It is kind of a big connector with 30 wires in it split into 2 rows.

channoff

Thanks for the info, DennisMik. I'll tinker around with the diagnostics and see what I can figure out. I still think it looks like a big procedure to replace the control unit if it is bad. Car has 142k miles on it, so I want to spend as little as possible on this repair.

channoff

UPDATE

So, something I forgot to mention was the laundry list of CELs at same time, U1001, P1574 x 2, and P1212. After combing this site, I finally found the thread I was looking for:
https://maxima.org/showthread.php?t=652640

Definitely a failed ABS control module.

Now off to the three other major problems - the ridiculously hard shift from 1st to 2nd, the world's periodically loudest heater A/C, and the no heat while idling issue.

Brudface

Yes that is definitely the issue... replace the module and you be set... its a big giant pain in the *** to get to though. Make sure you have the tools both I and paradiddle mention!!! Have fun and good luck

channoff

Brudface, Any pointers you can give to simplify? I would really appreciate any pointers you can give.

channoff