Hi,

Do you guys know if it is possible to replace ABS Control unit (or just 2 ABS relays) without disconnecting hydraulics from ABS actuator (i.e. without the need to bleed the brake fluid) ?

I have a 2002 Maxima SE 3.5L A/T. Recently I noticed occasional irregular ABS-like noises (not normal ABS sound) when braking. A few times ABS light came on. I also notice a fast relay clicking sound coming from the front of the car for a few seconds at a time, but I was not able to trace it to any specific relay yet. I suspect ABS relays.
It looks like 2 ABS relays are located in the black plastic box attached to ABS actuator assembly (actuator, control unit and relays are all together).
If I knew for sure that the problem is with the control unit or actuator, I would just do the replacement properly, but for now, maybe I can just clean/shake/re-solder the relays if they can be removed without the need to replace break fluid. Small garage in the complex, no lift. Management does not want anybody to work on cars there.

 

Instead of jumping in and replacing something based on guesswork, why don't you run the self diagnostic built into the ABS system and see what that says? The problem you describe could be a bad wheel sensor or (believe it or not) a bad wheel bearing.

The self diagnostic will make the ABS light in the instrument cluster blink out a code. You look up the code in the service manual and go from there.

Here is a link to the brake section of the 2000 manual. This information was not printed in the 2002 or 2003 manuals for some reason.

http://boredmder.com/FSMs/Nissan/Maxima/2000.5/BR.pdf

Instructions on how to run the test is on page 49 & 50. The decoder for the blinks is on page 62.

 

The entire module CAN be removed without taking the actual pump out of the car. It is a huge PAIN but WAY less than disconnecting the brake lines. I am going to be honest with you though I doubt that its anything inside the module, when they go, they go. You get nothing, nadda, not a thing. I've been through this on my own car. My dash was like a Christmas tree, my speedo wasn't working and I wasn't tracking mileage as well. You can't just open the module and replace a relay inside the module.
You'll have to search for a new module, whether or not it comes with the pump (which 10 times out of ten it does). I don't believe it to be the module though. I have to suggest driving it a bit more and understanding where the noise is actually coming from. IF it was then your ABS light would be illuminated at all times. as soon as it senses anything strange it shuts it off. I would run the diagnostics OR check all four speed sensors to make sure they are in the appropriate range with a multimeter.

 

Hi fellow Ontarian. When you say no tracking mileage, you mean the odometer stops rolling?

Did you end up replacing your module with a brand new one? I ask only because I asked the local dealer for a quote, and the module is a few thousand dollars.

 

Thank you for your responses guys! Very useful info.
That ABS-like noise and relay clicking sound are gone now (for 2 days). No ABS warning light either. I'll wait till it starts doing something again

 

When my module went it just gave me an ABS light and the ABS stopped working. No other drama. I drove it like that for about a year.

Yeah, Ni$$an wanted a lot for it. I got one from a salvage yard for $200 and it's been working fine. They made six different ones for my year and two were for 6-speed cars. Had do give the VIN to get the right part.

The install wasn't too bad. It's just a tight fit.

 

There is a difference between Auto and manuals. When the 6 speed ones go yes all you get is the ABS light, as the ECU does most of the calculations. For the automatic cars the calculations are all done via the module, OR TCM. I can't remember for the life of me, but when one goes so does the other. I can't remember if its the same for Auto's not equipped with TCS or not.

 

OK. I was thinking they might fail in different ways but this makes more sense.