Speedometer needle jumping around...

anbran · Post by **anbran** » 18 Jun 2011, 18:08

I've just noticed that the needle on the speedometer is, while I'm cruising at a constant speed, jumping back and forth about 10-15 km/h...

What's going on?

1999 XC70

Post by **jblackburn** » 18 Jun 2011, 18:10

Abs module or a conflicting signal from a wheel sensor

Post by **jblackburn** » 18 Jun 2011, 18:13

Whoops hit reply too soon. You can jack up your car and remove each front wheel. Behind each brake disc is a little sensor with a wire running to it. Unbolt it and clean the sensor and the reluctance ring on the axle with an old toothbrush and some kind of solvent. Check to make sure the connector has a good connection and the wires aren't frayed.

Are your ABS/TRACS lights on?

anbran · Post by **anbran** » 18 Jun 2011, 18:45

Well, heres the thing...I had the left wheel off to remove the hub...and I had to remove the sensor from the knuckle. When I installed it, the little screw broke, so the sensor is not secured very well at all. Just sitting in there. I was getting ABS activation without needing it, so I pulled the fuse for the ABS.

I guess thats it then?! I thought the sensor was only for the ABS and TRACS...not speedometer.

anbran · Post by **anbran** » 18 Jun 2011, 18:47

...and yes, the ABS/TRACS and "!" light is on

Post by **jblackburn** » 18 Jun 2011, 18:51

The speedo signal comes from the ABS wheel sensors and up through the ABS module. This is a part that would be great to get from a junkyard or someone parting out a car.

Im not 100% sure, but I think the sensors from all 1996-2000 models are the same. You can find out with a quick part number search through the online vendors at the top of the MVS page.

anbran · Post by **anbran** » 18 Jun 2011, 19:00

The sensor looked fine...The problem was securing it. The little bolt broke off and left half of itself in the knuckle. I guess the thing to do is get an extractor and then a new bolt and re-secure the sensor...?!

Post by **Ozark Lee** » 18 Jun 2011, 21:39

It will be a real PITA job but it is a heck of a lot cheaper than a new axle if you can repair it.

If it comes down to a point where you can't replace the screw I would even try to glue the ring back on with either epoxy or even silicone sealer. At that point you have little to lose and it might just work.

...Lee

Edit: I think I misread that - is it the sensor or the ring on the axle that is loose? The ring is a part of the axle assembly. If it is the sensor itself that should be fairly easy to repair properly, even if you need to double nut it to get the old bolt out.

Post by **FlyingVolvo** » 18 Jun 2011, 22:58

I'd just use silicone. If you let it dry, it will be strong enough to stay on through whatever conditions, but it can still be removed if necessary for other repairs.

anbran · Post by **anbran** » 19 Jun 2011, 05:55

How do you "double nut" it to get the old one out? This sensor is a black thing about 1.5 inches and about 1/2 in. thick. The wire is perm. part of the sensor. (I believe the sensor on my 98 had a disconnect at the sensor...?!)

Thanks for the ideas guys. Appreciated as always!

One other thing...Would PB Blaster cause some sensing problems? I recall that I soaked everything to loosen some of the bolts.

**Also, I didn't finish the hub removal job as I couldn't budge the lower control arm to knuckle bolt. Any suggestions??

Thanks