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Discussion Starter · #1 ·
Hey all. Car is a 99 V70 AWD, been having a recurring fault code on the left front speed sensor, intermittently causing ABS and cruise control to drop out. I've tried changing about everything, no luck, fault coce remains. A few weeks ago I had to change rear bearings, since they are pressed in I had to take the whole spindle to my buddys shop to get new ones pressed in, and the Volvo manual specifically said NOT to unplug the ABS sensors, but to remove them from the spindle. Plastic tab that the bolt goes through broke off immediately, so I had to knock them out from inside the spindle, as carefully as possible. No visible damage to the sensors.

Anyway, job well done and bearings are working fine, then suddently the speedometer goes out, as does the odometer and trip counter, and the brake warning light pops up. I presume the ABS light as well, however the bulb is broken since it was on all the time. I pulled over immediately, checked brake fluid, heat off brake pads anf discs (nothing special or out of the ordinary) , no visible fault. Car slowed down like it always does, so I'm guessing there's no mechanical error here. Speedo was out for a 300km drive today, only coming back on now and then for short periods.

I'm stuck. It seems odd the rear ABS sensors should affect speed signal, I've come to understand only the front sensors contribute to speed signals. I'd like to think the ABS module is good, previous owner, which is my uncle, said he swapped it for a factory new one about four years and 80k kms ago.

I haven't been able to read out any codes yet, anyone seen these symptoms before? Appreciate any input.

Sent from my D6603 using Tapatalk
 

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How are the wheel speed sensor rings on your front axles? My buddy's 98 S70 was having some weird abs issues that resulted from a corroded sensor ring on the front axle. I've also seen this happen on a first gen S40 after a bad wheel bearing damaged the teeth on the sensor ring.

ME7 can do some very strange things if the abs module isn't reading or outputting vehicle speed signal to the ECU properly. This is independent of the speedometer functioning or not. If the ECU isn't reading vehicle speed, it can go as far as to set a hard rev-limiter.

The ABS rev limiter was something we discovered while tuning my car after the M66 swap - I had a front wheel speed sensor that intermittently cut out. My tuner was able to disable the abs limiter for tuning purposes until I could repair the sensor.

Do yourself a favor. Go get the abs codes read and quit shooting in the dark.
 

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Discussion Starter · #4 ·
All four rings are crackless, seems even and in good shape. I'll have a buddy drive it afterwards while I hook up VIDA to the car for reading real time ABS pulses - the DiCE is what I've been waiting for.

Just wondering if speedo loss is a normal error on ABS module fault.

Hawtdayum
 

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Discussion Starter · #6 ·
Nope, I've made sure they are all tight and without play.

Had the car out for a drive yesterday, ofcourse the DiCE unit wouldn't communicate with the car. VIDA and DiCE are so full of bugs, I'll revisit the issue when I get the time, probably next week.

Hawtdayum
 

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98 v70 r abs

I have a 98 V70R and I am not getting intermittent ABS warning lights (when this happens I believe the TRACS OFF light is mandatory, and comes on also). I can tell you that the ABS/Tracs warning light trips do not automatically disable the speedometer.

I have not yet checked all the rings and senders, nor axle bearings, etc but will shortly. The warning light comes on from the start, or comes on during a drive, and sometimes goes off during a drive, or fails to come back on after the car is turned off and on again. Makes it harder to diagnose when it is intermittent like this.

Anyone have any good ideas on an intermittent problem like this ?

Thanks!
 

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^my father who has the car (was his, then mine, now his again while i'm overseas, he claims it's always been his!). Anywho already told him about midwest ABS and getting the unit redone. It's never been done on it so almost surely the issue. Sorry for the threadjack.
 

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^my father who has the car (was his, then mine, now his again while i'm overseas, he claims it's always been his!). Anywho already told him about midwest ABS and getting the unit redone. It's never been done on it so almost surely the issue. Sorry for the threadjack.
Damn kids !
 

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Discussion Starter · #10 ·
I got the DiCE hooked up last night and read the ABS sensord while my buddy drove the car... right rear sensor can't be read. Also, after a while, the DiCE lost comms with the ABS module, at the same time as the speedometer died, this tells me the main fault is in the module. I'll get that resoldered before I start swapping sensors. Anyone have a good writeup on the module repair?
 

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Discussion Starter · #11 ·
Just to finish this one off (sorry for bumping), the module was at fault. Or rather, the dude who repaired it. PO apparently lied, since he said it was swapped for a factory new one, it had clear toolmarks on the sides, and had been sealed with a thin stripe of silicone, not suitable for the environment. It was hardened, brittle and I could crack the module up with my fingers.

I resoldered all of the external connector points, stuck it back together with a generous amount of glue called Tec7 (dunno if you guys have it, but it's a wonderful thing, sits like hell and stays flexible in aggressive environments), and plugged it back in. ABS, Speedo, CC, and Tracs are all back up, been so for a week. All sensors read fine.

Thanks again for all your replies.
 

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Glad you got it fixed, and thanks for reporting back with results. Too often threads like this end without a solution.
 

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McShake,
Did you ever get any codes during this? I am having almost the same issues: My speedometer is intermittent, the abs and traction control lights are on constantly and the check engine comes on sporadically. After reading a couple threads (to include this one) it looks as though the leaning is toward the module. I have checked the sensors and other related parts and they all seem to be in good condition/working order. I do not however have access to vida/dice so I haven't run and the dealer wants way to much to just perform a scan. On a side note, during inspection I found a torn axle boot (address this once I receive the kit).

Any help would be appreciated.
 

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Received module, very quick and helpful company. Matt even helped me with ordering. Installed during lunch and other than the tab breaking when removing it solved all issues, even the speedometer.

Definitely a company I would suggest/endorse to others:partywave:
 
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