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2000 v70 ABS turns on without touching brake

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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dj_v70
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Year and Model: v70 2003
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2000 v70 ABS turns on without touching brake

Post by dj_v70 »

My v70's ABS has started coming on randomly while driving. I first noticed it when tapping on the brakes lightly, you could hear/feel the characteristic ABS pump action. But now, I can't drive a mile down the road without it happening several times and I am NOT even touching the brakes. It seems to be independent of speed and tapping the brakes seems to stop it, sometimes for a second and sometimes for several minutes. I am now concerned to drive the car.

Recently, I noticed that the passenger front has torn outer CV boot and the sway bar link has snapped. At the time, I figured I could drive it like that around town and replace those when it get warmer. Could those issues possibly be related to ABS? It is just too cold, so I am likely going to park the car for a few months unless anyone has any quick suggestions for ABS. I believe that I can't disconnect ABS without losing speedometer, odometer, etc. As such, I don't want to do that (but I would be thrilled to disconnect ABS otherwise if there was a way).

There are no error dash lights. I checked the axle nuts and was able to tighten a quarter turn on either side (~30 ft lbs), I thought I found the issue. Took a test drive and the issue still exists:(

scot850
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Post by scot850 »

Did you check the abs sensors on the front wheels? The cables run close to sway bar link so maybe it has damaged the wires. Also is the outer cv boot has split, grease may have got onto the reluctor ring blocking the sensor.

Neil.
2006 V70 2.5T AWD Polestar tune
2000 V70 R - still being an endless PITA
2006 XC70 - Our son now has this and still parked in our garage
2003 Toyota 4Runner V8 Limited
2015 Kia Sportage EX-L - Sold
1993 850 GLT -Sold
1998 V70 XC - Sold
1997 Volvo 850 SE NA - Went to niece in California - Sold
2000 V70 SE NA - Sold

dj_v70
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Post by dj_v70 »

scot850 wrote: 30 Jan 2022, 09:07 Did you check the abs sensors on the front wheels? The cables run close to sway bar link so maybe it has damaged the wires. Also is the outer cv boot has split, grease may have got onto the reluctor ring blocking the sensor.

Neil.
Thanks for the input, those are good ideas. I have snow on the ground at the moment so I can't jack it up, but will once weather gets better I'll look into that.

I have a VIDA/DICE laptop, however, the battery is shot on it. Does anyone know whether DICE will tell me which corner is the offender realtime? If so, I'll load another laptop and take it for a ride with laptop connected to determine that first (that might take awhile also as my other laptop is at a relatives out of state).

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FireFox31
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Post by FireFox31 »

I am having a more extreme version of this problem, documented in this thread. Carefully and completely clean each tooth of both reluctor rings and that should stop the ABS engagement while coasting. I bet there's grease in one so the car is getting a bad read on how fast that wheel is spinning. I haven't solve the ABS while braking yet.

You can disable ABS while maintaining your speedometer and odometer. Disconnect the black two-wire power connector on the ABS module. It's next to (and a little hidden by) the large data cable on the ABS module. Squeeze the clips on either end to release. The data cable is kind of in the way but you can squeeze in there if you're careful. The attached picture (not my own) shows the power cable.

If you choose to remove the data cable, know that the cover is connected to a pair of rails which diagonally release the connector from the harness. Open the cover carefully and firmly, gently pulling the cable away from the module at the same time. Simply yanking up on the cover can easily break those rails off. It's fine if that happens because you can manually slide them, but you have to move each one a tiny bit, switching back and forth. When they're connected to the cover, that moves both at once. And when reinstalling the data cable, gently press it onto the connector while lowering the cover, assisting those rails in doing their job of pushing the cable in to place.
Attachments
ABS power.jpg
FireFox31
Blue 2000 V70 NA manual, "the V70" - died, reborn, totaled, donated, stripped
Green 2000 V70 NA automatic, "the G70" - awaiting 2nd rehab
Black 2000 V70 NA automatic, "Geronimo" - rescued, rehabilitating
Blue 1998 V70 T5 manual, "the T5M" - awaiting rehab

dj_v70
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Post by dj_v70 »

FireFox31 wrote: 30 Jan 2022, 12:41 I am having a more extreme version of this problem, documented in this thread. Carefully and completely clean each tooth of both reluctor rings and that should stop the ABS engagement while coasting. I bet there's grease in one so the car is getting a bad read on how fast that wheel is spinning. I haven't solve the ABS while braking yet.

You can disable ABS while maintaining your speedometer and odometer. Disconnect the black two-wire power connector on the ABS module. It's next to (and a little hidden by) the large data cable on the ABS module. Squeeze the clips on either end to release. The data cable is kind of in the way but you can squeeze in there if you're careful. The attached picture (not my own) shows the power cable.

If you choose to remove the data cable, know that the cover is connected to a pair of rails which diagonally release the connector from the harness. Open the cover carefully and firmly, gently pulling the cable away from the module at the same time. Simply yanking up on the cover can easily break those rails off. It's fine if that happens because you can manually slide them, but you have to move each one a tiny bit, switching back and forth. When they're connected to the cover, that moves both at once. And when reinstalling the data cable, gently press it onto the connector while lowering the cover, assisting those rails in doing their job of pushing the cable in to place.
Thanks for having the same problem first:). That save me a lot of time. I am going to disconnect that ABS motor and drive it like that until spring thaw. Excellent directions!

454cid
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Post by 454cid »

dj_v70 wrote: 30 Jan 2022, 14:57 Thanks for having the same problem first:).
LOL, That's hilarious! :lol:
1996 850
1999 S70 GLT (sold after deer hit)

2010 Ford Focus SE
2006 Cadillac CTS
1996 Mercedes C220
1999 Chevrolet K3500
1969 Buick LeSabre Custom 400

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