Famous DSC/ABS/BRAKE Trifecta problem

[GunnyGlow]

I had a similar problem an indy couldn't diagnose.

Took it to Dealer and they found a blown fuse in panel under glove box. #9 or #10 I think.

[white46]

Originally Posted by Doru

I asked if it was intermittent, because "usually" when it's intermittent, it's the ABS module. If it's solid, then it's a sensor. But I can be wrong.
However, if you removed the ABS, you need to do the following steps:

-removal and install should be done with the battery unhooked, as it can damage the ABS module. Reconnect battery.
-if it's a new ABS module, it should be coded to the car (I used SSS Progman)
-if it's a new or remanufactured ABS, the next step (for both cases) is to re-cablirate the following sensors (I used GT1/DIS 5.7):
Steering angle sensor
Rate of rotation sensor
Lateral acceleration sensor

When calibrating these 3 sensors, the front wheels & steering should be pointed in a as much as possible straight position. The car has to be on a level surface. Battery 100% & battery charger hooked to it.

Once you have done these steps, erase ALL codes, then go for a test drive and see if any errors return.

If you have a solid "trifecta" and your scanner tells you it's a wheel speed sensor, you need to test all 4 of them. The best way, is to take the ABS plug off, then test at the connectors (it's easier than to take the wheels off). The speed sensor readings should be around 7.5 ohm (+/- 0.2) one way & 4.5(+/- 0.2) ohm with reverse polarity. If one reads different by big amount (or "0"/ infinity) that sensor is toast. if you don't know the ABS pins layout, I can provide them to you.

If the wheel speed sensors test good, the next step is to check the pressure sensor (goes at the back of the whole ABS module - where the brake pipes are). You need a helper here. Ignition on, and the helper presses the brake pedal. With the pedal off, it should read "0"V or close. With brake pedal pressure applied, it should start reading between 0-5 volt. the "5" volt is at max brake pedal pressure - around 250 bar? So your voltmeter should not exceed that value.

if this test is a pass, then you are left with the rotation rate sensors, acceleration sensors and steering wheel sensor. These sensors I am not 100% sure how to test, but they should give you some error readings when you try to calibrate them, I would believe. Also the GT1 might point you in that direction - I am not sure, because I haven't encountered that issue on any of my cars.

Hi Doru,
Remanufactured ABS meaning repaired ABS module? If so, I need to calibrate those 3 sensors?
Also, aren't Rate of rotation sensor and Lateral acceleration sensor the same part?

Thanks.

Originally Posted by GunnyGlow

I had a similar problem an indy couldn't diagnose.

Took it to Dealer and they found a blown fuse in panel under glove box. #9 or #10 I think.

I checked all fuses but none of them are blown.

[Doru]

Originally Posted by white46

Hi Doru,
Remanufactured ABS meaning repaired ABS module? If so, I need to calibrate those 3 sensors?
Also, aren't Rate of rotation sensor and Lateral acceleration sensor the same part?

Thanks.



I checked all fuses but none of them are blown.

Yes, the repaired module does not need to be coded, but the sensors need re-calibration. The 2 sensors I believe are different - I had to perform one test for each of those sensors.

[Helihover]

The sensor is the same. Meaning only one sensor (with three different names).

If you read the first page of the link I posted it list all related sensors, modules, switches, and buttons.

[Helihover]

[white46]

Thanks for help guys.

Here is update.
So last night, I drove the car around crescent only without re-calibration (don't have plate nor insurance for this car yet), and DCS/ABS/BRAKE lights were still on.
Parked the car in garage, removed all relating fuses (about 5 total) and nothing was burnt, so installed them back, then went to bed.

This morning, started the car just to move couple ft, (to clean up garage little bit) then realized DCS/ABS/BRAKE lights were OFF.
I couldn't believe my eyes... Those damn lights were OFF!
Drove around crescent again, restarted the car few times, and those lights remained OFF.

Hopefully it stays this way............

[Ricky Bobby]

update has your trifecta remained off?

My ABS module was rebuilt but still throwing an intermittent trifecta on the highway. I am going to recalibrate the sensors but I it is pointing to the brake pressure sensor or the brake light switch.

[white46]

Mine remains off ever since then.

Since yours is intermittent, I don't think recalibrating sensors will do trick.
Must be some sensor malfunctioning.

[Ricky Bobby]

Originally Posted by white46

Mine remains off ever since then.

Since yours is intermittent, I don't think recalibrating sensors will do trick.
Must be some sensor malfunctioning.

Yes it literally comes on during highway drive. Shuts off at next drive cycle with a left to right steering angle reset (resets all sensors). Will scan with DIS later

[Riggodeaux]

After turning the actuator gear as a temporary fix about 10k miles ago, I pulled the transfer case actuator motor and replace the nylon/plastic gear. PITY to get the cover plate off, otherwise, pretty easy; access on the E53 is pretty clear, though I did mine with the front end up on rhino ramps, making for a tight fit from behind the front wheels for a 220+ lb. guy. The old gear was worn to down in two different places. Trifecta now gone .... the problem seems to be the 'worm' gear intersecting with the plastic/nylon gets off wack and chews up the plastic nylon. multiple plastic shavings in the old grease.