andy_s273

So you know when you turn the car on and all the lights illuminate then go away? Well the abs light and the green spinning wheel dont seem to come on. and my traction control doesn't engage. Now Ive read about problems related to mine but the difference is the abs light isnt on. I also suspect this to may be a possible tune done by the previous owner. its been a while but on start ups and random times, the traction control light would come on and disappear. the most recent time was when i replaced the intake manifold. I disconnected the battery so i assume that it reset the ecu for a moment then went back to tune settings. Is this a possible scenario?

I went ahead and checked the fuses with a circuit tester (test light) and the following dont seem to work.

4 RH Low Beam Headlamp
6 Starter Motor Relay
10 LH Low Beam Headlamp
35 Shift Lock Actuator, PCM, Speed
Control Servo, ABS Module
37 Adjustable Illumination
38 Highbeams
41 Brake Lamp

Im not concerned about the lighting, they work (but im also confused about the starter motor relay fuse). I also tryed to swap in a good 15A into slot 35 and nothing. Its like the actual fuse port isn't getting power but i suspect that it'll only test well once the abs is actually online. So i also suspect that With a failed abs module theres no way to tell. i havent checked any wheel sensors, or the actuall bulb in the cluster because i doubt both lights in the cluster and the tc switch are at fault. what are your thoughts?

thanks for any feedback and sorry if youve seen this question before its just annoying to know that my vehicle has a tiny flaw.

blu30val

I'm just kind of getting into electrical diag, and what I do know is all methodical. I suggest finding the appropriate wiring diagram for the abs/ Trac control circuit and take it from there. I suggest avoid using a power fed test light unless you know what your doing(power probe). Really depending on you technical skill level and tools available to you, you may benefit from taking it to a shop. Post vehicle details too, like yr and model( I'm assuming a gt). Maybe someone else has a quicker way to check for common problems, but overall I suggest breaking out a wiring diagram, multimeter, and maybe a factory level scan tool to get a diagnosis.

cliffyk

Disconnecting the battery will not "reset" the tune. The tune is stored in an EEPROM, (Electrically Erasable Read Only Memory) that can only be erased by applying +18 V to pin 13 of the OBD2 connector and then deliberately writing to the memory chip.

Fuses #8 (50 A) and #17 (20 A) in the Battery Junction Box are power to the ABS module motor and solenoids;

Fuse #29 15A in the Central Junction Box (CJB, under the dash) is the main power to the ABS module microcontroller;

Fuses #35 (15 A) in the CJB received power from the Brake Pedal Position switch, which is powered by fuse #33 (15 A) in the CJB. Fuse #35 only has power when the brake pedal is depressed. Fuse #33 also power the stop lights and front signal lamps in "hazard" mode.

First thing to do is check fuses 8 and 17 in the battery box, then fuses 29 and 33 in the CJB. If the brake or hazard lights works then fuse 35 in the CJB must be good.

After that if the ABS and t/c are still not behaving then it's time to suspect the ABS module. A common failure in the module is the MOSFET used to control the pump motor:



As you can see if it is burned out it will be obvious.

The original transistor is a Vishay SUB75N06-08, which has been superseded by part number SUM90N06-4M4P. DigiKey has these for $3.59 each.

To get at it you need to cut the plastic ABS module open along the bottom seam, a rotary wheel in a Dremel tool works great.


However if it was me I would view this as a great time to delete the ABS and traction control, and shed some weight. You can buy an ABS delete block from PRB Machining for $130:



And just get rid of the entire pile of unnecessary nonsense...

blu30val

^ I like this idea. Not to thread jack, but thanks again cliff. This part is essentially a bypass right?

cliffyk

Yes, a manifold block if you will. It is very nicely machined, fits with just very minor flexing of the OEM brake lines, and worth every penny...

andy_s273

I will get right on, now would there be any reason at all to check the resistance for every abs sensor

blu30val

I'm sure it comes with instructions, but will it keep the ABS light off and not set codes.

cliffyk

Yes.

The ABS module is a stand-alone unit that has no connection to the PCM (it communicates externally over the ISO 9141 bus, pin 7 of the DLC). It controls the ABS warning and t/c indicators in the instrument cluster--when the ABS module is removed they remain off.

Make sure you remove all ABS related fuses, 8 and 17 in the BJB and 29 in the CJB.

The best part about this is that it is reversible if you should sell the car and some jerk wants ABS and t/c. Just stick the pump assembly back in and plug in the fuses...

blu30val

Right on. I knew that some newer cars have all kinds of bcm's, wasn't sure about my 02, haven't messed around too much with it. Again, thank you.

andy_s273

Well all fuses related to abs check out ok. Its about 79-99 for repair. Go ahead and send it in?