ABS unexpected activation

QuirkyAero

Registered Member
Original poster
Jun 22, 2020
18
Seattle, WA
I have a 2006 9-7x 4.2 that activates the ABS just before it comes to a stop on medium braking. Doesn't do it on soft braking, doesn't do it on hard braking. I realize these are relative, the point being it does not happen all the time, but can be made to happen consistently under some conditions.

There are several recent threads covering this. Common feedback suggests ABS sensor bad. I am on board with that, but...

I replaced the whole front end suspension, including the bearing hubs that came with ABS sensors and cables pre-installed. These are new as of July , for 4-5 months of service. Here is what the Tech2 data gathering shows:
Tech2 9-7x 2006 4.2 braking.JPEG

The right front wheel sensor has a definite drop off at low speed. It appears to be a consistent drop off over many stops, and sometimes the ABS kicks in, sometimes not.

Would this kind of drop off suggest ABS Sensor issue, or perhaps cable issue, or bad connector, or...?

These are the hubs I put in in July:

Thanks,
Bernard
 

TJBaker57

Guru
Aug 16, 2015
2,000
Colorado
I have a 2006 9-7x 4.2 that activates the ABS just before it comes to a stop on medium braking. Doesn't do it on soft braking, doesn't do it on hard braking. I realize these are relative, the point being it does not happen all the time, but can be made to happen consistently under some conditions.

There are several recent threads covering this. Common feedback suggests ABS sensor bad. I am on board with that, but...

I replaced the whole front end suspension, including the bearing hubs that came with ABS sensors and cables pre-installed. These are new as of July , for 4-5 months of service. Here is what the Tech2 data gathering shows:
View attachment 98786

The right front wheel sensor has a definite drop off at low speed. It appears to be a consistent drop off over many stops, and sometimes the ABS kicks in, sometimes not.

Would this kind of drop off suggest ABS Sensor issue, or perhaps cable issue, or bad connector, or...?

These are the hubs I put in in July:

Thanks,
Bernard

By any chance was this issue ever seen before the hub changeout? That could point towards a wiring issue between the sensor connector and the EBCM.
 
OP
Q

QuirkyAero

Registered Member
Original poster
Jun 22, 2020
18
Seattle, WA
Yes and No :smile: The system under the old hubs would sporadically activate the Traction Control: The TC light would come on and throttle was reduced during those episodes.

The old left front hub had rusty water in it when I pulled the ABS sensor. Amazed it was working at all. The TC issues went away with the new hubs/sensors. Life was good.

Some weeks ago the ABS activation started to occur. So there was a period of several months when everything was working correctly.
 

TollKeeper

Platinum Donor
Dec 3, 2011
6,401
Brighton, CO
Sounds like you got a defective hub, or fragments that are stuck on the tip of the sensor.
 

MRRSM

Lifetime VIP Donor
Oct 22, 2015
5,714
Tampa Bay Area
@QuirkyAero ... When time permits, would you contribute your information about your ABS Test Procedures and Screen Print Images of your Tech 2 Use to the Thread titled?

"Additional Tech2 Resources"


And Check Out and Download the PDF for the A-Z "Step By Steps" in support of the Best Ways to Key through the various choices to Make the Most of ALL the Utilities offered by the "GYMKO" Tech 2 Hand-Held Scanner in Post # 15 in that Thread ...courtesy @GENMOTMAN.

When you make the exchange for the Replacement Wheel Hub-Sensor Combo... It won't hurt to pull out the A/C Sensor Probe and check the end for anything like left-over factory 'detritus'...AND...Put some Brake Lube around the Cleansed Sensor Mount position and then tighten-snug things back up. Its Prep that perhaps should be part of the R&R routine for anyone doing this job ...Just to be Sure of the matter before you have to Torque Down the Huge Bolts holding on the Brake Caliper Bracket(s). :>)

For those of us who do NOT own a Tech 2 ...another approach to determining the performance of the ABS Wheel Sensor is with a decent DMM or DVOM. This is my favorite "How To Video" using that same equipment:

 
Last edited:
OP
Q

QuirkyAero

Registered Member
Original poster
Jun 22, 2020
18
Seattle, WA
I can do that. I'll need to get a few more pictures of the steps to select the items to snapshot, etc.

At the time I installed the hubs, I debated pulling the sensors, but did not. Perhaps not a wise choice. Buggering up the stupid 5 sided "hex" bolts did factor into that decision. I pulled the sensor out of the old hub using a 5 sided Torx lightly pounded into the bolt -- from Internet suggestion :smile: Is there a better way?
 

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