ABS kicks in at low speeds...Driving me insane.

[Tom P]

Good information regarding the abs issues so far. As someone else posted, those "rounded off head" sockets usually save the day.

Also, last I checked amazon had the precision bearings with sensor for about $100.

I know, they aren't horribly expensive, but my wheel bearings are in really good shape as of right now. No play or noise of any kind, so spending $200 to replace them takes a pretty good bite out of the budget. Especially since I'll have to cherry pick my projects for the next 6 months or so and go with whats absolutely necessary vs. whats an annoyance I want fixed. And I pretty much have to sell the wife on my endeavors too

 

[Christian Steffen]

I know, they aren't horribly expensive, but my wheel bearings are in really good shape as of right now. No play or noise of any kind, so spending $200 to replace them takes a pretty good bite out of the budget. Especially since I'll have to cherry pick my projects for the next 6 months or so and go with whats absolutely necessary vs. whats an annoyance I want fixed. And I pretty much have to sell the wife on my endeavors too

I hear ya, if they're in good shape I'd just kill the abs then.

When I was in college I had one of the abs sensors go, and didn't want to spend my beer money on a new one (I was close to the end), so I ran without abs for the majority of a winter. As long as you're aware that it isn't working, it's not a huge deal. Just have to be more cautious. Unless you let other people drive your truck.

 

[Tom P]

I don't think Ill be letting anyone drive my truck, especially not if the roads are crap.

 

[east302]

Here's the TSB on it that someone referenced earlier...

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[Tom P]

I found that info while researching the issue. Its good to know, but unfortunately it was never a recall and my truck of course no longer has warranty.

 

[EppNation]

Had similar issue on my burb, after replacing fluid out of reservoir with a turkey baster and refilling twice along with adjustment of rear drums that was needed the symptom has subsided.

And talk about bearings... FYI I opted for these raybestos hub bearings and 2 years/ 30K miles later one of them is already bad.

Raybestos 715041 Professional Grade Wheel Hub and Bearing Assembly https://www.amazon.com/dp/B001DAGEIS/ref=cm_sw_r_cp_apa_tninAbPVQZGJC

[emoji121]️NOT recommended [emoji121]️

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[Ken K]

I look at Rock Auto parts since I don't work on these every day. If one of the front ABS sensor's air gap has increased due to rust under it bolt flange, pushing the sensor up, will cause this exact issue every time. I have seen TSB's on this issue for years due to the signal drops bellows the ABS modules low signal threshold. Now, the target wheel or reluctor is enclosed inside the wheel brg/hub assembly. The sensor has one bolt (probably allen head) and sit on top of the 4 bolts flange that holds the hub onto the steering knuckle. You may remove the dust shield to remove it. But first, check it. With a DMM set on A/C voltage, carefully rotate the wheel(s) and watch the reading. It should remain steady but changes with wheel speed and does so smoothly. Many use a dual signal lab scope also. Check terminals in the connectors as the use an extension harness to get from the far wheel, back to the ABS module. The harness can be bad with high resistance. The wires inside the sensors leads, are twisted 9 times per foot and not to be repaired. Twisting help reduce high voltage induction signals. I would use dielectric grease in all connectors. With a factory supported scan-tool, like the TECH2, the signal and wheel speed will be shown helping you to which sensor is the problem. If this system is 3-channel, using one sensor in the differential, steel dust from worn bearings will collect on the end of the sensor because it use a magnet with a wrap of wire around it. We call these types, PMG's or permanent magnet generators. You can test resistance in ohms and compare each sensors readings is one way if you can't find the TECH2, because you neighbor didn't return it. Best of luck / Happy Holidays. Retired ASE Master Tech.

 

[Tom P]

I look at Rock Auto parts since I don't work on these every day. If one of the front ABS sensor's air gap has increased due to rust under it bolt flange, pushing the sensor up, will cause this exact issue every time. I have seen TSB's on this issue for years due to the signal drops bellows the ABS modules low signal threshold. Now, the target wheel or reluctor is enclosed inside the wheel brg/hub assembly. The sensor has one bolt (probably allen head) and sit on top of the 4 bolts flange that holds the hub onto the steering knuckle. You may remove the dust shield to remove it. But first, check it. With a DMM set on A/C voltage, carefully rotate the wheel(s) and watch the reading. It should remain steady but changes with wheel speed and does so smoothly. Many use a dual signal lab scope also. Check terminals in the connectors as the use an extension harness to get from the far wheel, back to the ABS module. The harness can be bad with high resistance. The wires inside the sensors leads, are twisted 9 times per foot and not to be repaired. Twisting help reduce high voltage induction signals. I would use dielectric grease in all connectors. With a factory supported scan-tool, like the TECH2, the signal and wheel speed will be shown helping you to which sensor is the problem. If this system is 3-channel, using one sensor in the differential, steel dust from worn bearings will collect on the end of the sensor because it use a magnet with a wrap of wire around it. We call these types, PMG's or permanent magnet generators. You can test resistance in ohms and compare each sensors readings is one way if you can't find the TECH2, because you neighbor didn't return it. Best of luck / Happy Holidays. Retired ASE Master Tech.

Thanks for the detailed info! When I get ready to do the job I'll unplug the two sensors independently to try and get a feel for which one is the culprit. IF I do replace them it will be both at the same time and most likely with new bearings.

Had similar issue on my burb, after replacing fluid out of reservoir with a turkey baster and refilling twice along with adjustment of rear drums that was needed the symptom has subsided.

And talk about bearings... FYI I opted for these raybestos hub bearings and 2 years/ 30K miles later one of them is already bad.

Raybestos 715041 Professional Grade Wheel Hub and Bearing Assembly https://www.amazon.com/dp/B001DAGEIS/ref=cm_sw_r_cp_apa_tninAbPVQZGJC

[emoji121]️NOT recommended [emoji121]️

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Thanks for the info. Raybestos has never been a brand I've looked at. The brake pads I pulled out of my truck recently were raybestos and did not appear to be of decent quality. I know they used to be a decent brand but I'm guessing like most other brands, outsourcing has ruined their quality control to a degree.

My one gripe about Rock Auto is that they don't allow customer reviews of the individual product. That's one thing I do like about amazon when it comes to buying stuff. A thousand other people tried it before you so you can cherry pick whats good. I know with RA, you can usually get the AC Delco OEM parts for as little or nearly as little as the aftermarket stuff so that's what I'm trying to do, but it would still be nice to get some feedback on the quality of the part before you spend your money on it.

 

[Tachyon]

I did some digging and this is covered by TSB #020525006A and may have been covered by an eventual recall here:
https://www.consumeraffairs.com/recalls04/2005/gm_abs.html

I had the procedure sheet somewhere, I'm trying to find it. Meanwhile, I found this....

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[Beeffajitas]

I've pulled the fuses on both my GMT400 trucks. I had the same low speed activation. I even had to replace hubs and had fresh sensors, still did it. I'm in NE and drive in snow and I never felt like I was missing ABS. Get good tires.