2004 AT (110,000 miles) w/ DSC

The ABS and TCS lights both started coming on a while back. They will both come on and stay on once the brake pedal has been firmly depressed for the first time. There's a direct correlation to the brake pedal, as I can drive around without problem when using just the parking brake.

Just to be sure, I thoroughly checked out all the wheel sensors. No shorts were detected and the sensor resistivities were all within range.

I took the vehicle in for an ABS scan and a code C1290 (brake fluid pressure sensor) was read. The tech went through the recommended electrical trouble-shooting per the service manual but found no issues with the pressure sensor. I also tested the sensor myself and even replaced it without success. I too concluded that the ABS control module (CU) needs to be replaced.

From researching the subject, you supposedly have to recode the new ABS CU in order for it to communicate properly with the vehicle's PCM. You can't just simply swap the part out with a new/used one. I checked around my area (Houston), and was stunned to learn that none of the local Mazda dealer techs had ever replaced this part before. I don't know about you, but I'm not real keen about paying someone for on-the-job training when its on my dime (que the old Aamco transmission commercial).

I'm in need of some guidance at this point. Has anyone here had this recode procedure performed? As I'm obviously out of the warranty period, cost is a concern. How long did it take them to do the recoding and what did they charge?

Thanks to all!

 

I skimmed through the service manual for removing and installing the ABS Control Unit and I couldn't find any references to needed something programed.
Even if the unit does need "recoded", you'll likely need a WDS which only the dealers have.

 

NinjaJon:

I tried swapping the module out with a "used" one that I had purchased. Both lights would then came on and stay on immediately upon starting the vehicle. The resulting ABS code was C1805 (mismatched PCM and/or ABS/TCS module).

These modules are programmable and contain data that is unique to each vehicle. Hence the need to "recode" or reconfigure them with the WDS. From what I understand, there is a similar process that must be followed when replacing the airbag control module.

 

yep, when my alternator overcharged it fried my ABS (along with many other things) and the shop I had my car towed to could not replace the unit under my extended warranty because the unit can only be reprogrammed by the dealer. It was very expensive, I was very glad I got the extended warranty.

 

The ABS unit consists of two parts, the hydraulics (pump) and the electronics control module (ECM). Most of the time, it's the ECM that goes bad on the unit. Replacing just the ECM is relatively straightforward as it only requires the removal of six T-20 screws. And there's no to bleed in this case.

As 9krpmrx8 pointed out, replacing the unit outright can be an expensive proposition. I did a little shopping around online, and you can purchase a new unit complete for ~$1200 (www.trademotion.com). The shop (non-Mazda) that read my ABS codes quoted me ~$1800 (new unit + labor). I would then still have to take it down to a Mazda dealer to have it "re-configured".

I chose to install another unit (used) myself, but the used unit can't communicate at all with the car now. I need to take it down to a Mazda dealer for them to re-configure it...problem is none of their service techs down here are familiar with the procedure. What would an experienced tech typically charge to perform this procedure?

Thanks again to all.

 

did you sort out this programming issu?. I may need a new ABS control module and want to know what my options are because you are right its expensive as hell to do.
Same code, hoping its just wiring or something

 

You better off try to get one used from a wrecked car and start from there.

it should work, try your local junk yard as most of the people don't know how much these things cost and will just sell it to you for cheap.

 

do you know how hard it is to reprogram?

 

Hi, I'm new to the forum and I just started having the same ABS/Traction Control problem on my 2004 when stepping down hard on the brakes. If I ease to a stop, I can keep the lights from coming on. Once they're on, shutting the car off and restarting clears them until I brake hard again. I had the code dumped at the auto hobby shop at Ft Carson, and it was C-1290, brake fluid pressure sensor. I took the car into Mazda last week to have a clutch issue checked (some kind of crack in a unit that's covered by a maintenance bulletin) and I had them check the ABS light also. They found a blown fuse and replaced it, and said that if it blew again, the next step (according to their diagnostic manual) was to replace the control module - $2000. What worries me is that if they're just following a step-by-step maintenance guide from Mazda, and if they can't tell for sure the modules bad, there's no guarentee that this will fix it.

The engine was replaced about 10,000 miles ago (under warrentee, thankfully), and I replaced the back brakes within the last 1000 miles. The lights were coming on before I did the brakes though.

I'm going to try going through checking the wire connections to make sure they're tight. Any other suggestions are greatly appreciated.

 

I would say its much easier to check the sensors and wiring before you start replacing expensive parts.

You just need a multi-meter and some patience to do it.

and yes, sadly, MOST OF THE DEALERSHIP (not just Mazda, talking about ALL companies) are loaded with step by step monkey who can't fix **** without manual. So when something tricky comes up, they will be like oh we are out of ideas, good luck.

 

I think you need WDS to make the module "talk" to each other.

the system cost I think 1.7 K ?

the FM saids u need to use WDS to initialize the newly installed module. but do you really need to ? cuz I don't think the ECU or anywhere store those info. I could be wrong tho.

only way to find out is try it.

but I mean, even it doesn't work. bring the thing to dealership they should have no problem setting it up for you, for maybe an hour of labor charge. better than paying 2K for a brand new pump.

 

Do you know which fuse it was that they replaced?

 

If i call the dealer do you think they would know if they can do this or not? because i have heard that many of them dont know how to do the reprogram and i dont want to swap the part to find out they cant do it.

 

They replaced (supposedly) the brake light fuse. When i got the car back, the brake lights were not working and when I checked the fuse was blown again. I don't know if they replaced the fuse for the ABS and I haven't checked that one to see if it blew again.

 

The wiring harness for the middle taillight is shorting out. It's a common problem. There is a long thread with DIY instruction on how to disconnect the harness.