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1996 850R intermittent brake pulsation over bumps

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

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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wackenhut
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Year and Model: 850R 1996
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1996 850R intermittent brake pulsation over bumps

Post by wackenhut »

I have noticed in the last few days that at least one time per driving, the brake pulsates (seems like abs is kicking in) when going over bumps. This has never occurred before. Does anyone have any idea what could be causing this. There are no codes coming up. Any help is much appreciated.

Thank you.
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bmdubya1198
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Re: 1996 850R intermittent brake pulsation over bumps

Post by bmdubya1198 »

My '98 has done that too. How do your brakes perform otherwise? I always associated it with pads that are too hard, and don't seem to grab very well.
Otherwise, it would be a good idea to check your brake fluid to make sure it's at the proper level.
00 V70R Venetian Red/Charcoal M56 Swapped 200k
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00 S70 GLT Mystic Silver/Taupe 253k
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Re: 1996 850R intermittent brake pulsation over bumps

Post by abscate »

If the wheels are losing traction on a bump, the traction controls (TRACS or STC) uses ABS to control wheel spin - that might be it.
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wackenhut
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Joined: Tue Jul 07, 2015 9:32 pm
Year and Model: 850R 1996
Location: FLORIDA

Re: 1996 850R intermittent brake pulsation over bumps

Post by wackenhut »

Just strange that all the sudden this started happening
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WhatAmIDoing
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Re: 1996 850R intermittent brake pulsation over bumps

Post by WhatAmIDoing »

It is more likely for your wheels to lock up when braking on a rough surface, because there is more rolling resistance. I know on my last trip through PA, every braking event set off ABS because the roads are nothing but potholes.
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Re: 1996 850R intermittent brake pulsation over bumps

Post by tardcart »

start by turning tracks off, also may be the insulation is gone on the pump wires and they are arcing.
wackenhut
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Joined: Tue Jul 07, 2015 9:32 pm
Year and Model: 850R 1996
Location: FLORIDA

Re: 1996 850R intermittent brake pulsation over bumps

Post by wackenhut »

I just noticed now, that the TRACS OFF Light is permanently illuminated. Does this help any in the diagnosis of the issue?

Thank you
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bmdubya1198
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Re: 1996 850R intermittent brake pulsation over bumps

Post by bmdubya1198 »

Nothing changes when you hit the TRACS button? That could be indicative of a failing ABS module, or other ABS/TRACS issues. You can't get flash codes on a '96, right? You probably need Vol-FCR or 850-OBD2 on Android to read ABS codes.
00 V70R Venetian Red/Charcoal M56 Swapped 200k
03 S60 2.4T Silver/Black 118k
07 XC90 V8 AWD Sport Titanium Grey/Black 174k
92 245 Base White/Beige 249k
98 V70 GLT Black/Beige 205k
99 BMW 528i
84 BMW 318i
01 Mountaineer 5.0
Sold-
00 S70 GLT Mystic Silver/Taupe 253k
91 944 Turbo Dark Green/Beige 175k
93 944 Base Beige/Beige 221k
98 S90- Silver/Gray 207k
95 850 GLT Tropic Green... crushed
01 S60 2.4T Black/Black 230k
88 744 Turbo M46 Beige Metallic/Beige 188k
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