Hey gang been a while .... so busy lately....

Started today .... I've had ABS light for a while .... finally got around to changing both wheel hubs out a few weeks back .... no difference. Rear sensor seems clean.

today speedo stopped ......

How to track down ;)

If the speedometer quit then your rear sensor quit.

 

Rear sensor seems clean.

 

Appearance is meaningless. What matters that the sensor can produce a proper AC sine wave that ABS computer can use also that the 3 sensors all have the same frequency. If on is different that means that one is tripping the light and needs replacing. ABS system requires all sensors to match in frequency.

So any way to track down if it is rear ?

I believe that the DRB tool at the dealer can look at the individual sensors.  This is recalled from other posts, as I haven't tried diagnosing this problem myself as of yet.

I know it can on newer trucks ..... wasn't sure about older

Like down at work we've got a Innova handheld code reader that can read ABS errors and tell you which sensor is screwed up. Like this is a bit newer version than ours...

http://www.innova.com/en-US/Product/Detail/3120d

 

So I had it on a high dollar scanner - not a DRB but a full suite scanner.

No codes for ABS - only boost to high, injection pump (ppump) and TPS and grid heater.

 

Q) - The front two sensors on the wheels only control ABS right ? So even if there was a damaged circuit - that wouldnt impact speedo and odometer.

 

So basically the only fault for speedo/odometer could be the transmission sensor (auto) or the rear sensor ?

Ohm out the rear wires  from under the hood. 

 

On my truck the junction above the drivers front was really beatup due to salt etc.  I had to redo pretty much all wires in the loom.

Wires and sensor both ohm ok from the rear .... literally get a reading by closing circuit on sensor ... or on sensor harness

Sensor looked fine ... no shavings ... teeth looked ok from what I could see

New sensor on order here in a couple days

Anything else to check ?

Maybe a new mechanic

Ha ha .... where's the butt kick icon .... drive over and fixit for me then.

Starting to wonder if ABS module is dead. Cluster is fine.

Seems like I remember people having abs light after p-pump swap, maybe just now catching up with you. Pull the bulb and keep on truckin!

Haven't heard that one. Not worried so much about ABS .... but speedo and odo

Rear diff sensor got my speedo back. Oem only, oriellys one failed. abs light is most likely the control module. Have a mechanic check it with the snap on reader and if it cycles on and off then it's bad

Typically if the ABS light is on then there is a problem within the ABS system be it sensors or ABS controller.

So theres no interaction between sensors at front and speedo/odo ?

 

Basically sensors at front for ABS only.

 

Sensor at rear diff for speedo/abs ?

So theres no interaction between sensors at front and speedo/odo ?

 

Basically sensors at front for ABS only.

 

Sensor at rear diff for speedo/abs ?

 

Correct. The front two sensor have zero bearing on the speedometer only the rear sensor takes care of the speedometer and odometer.

Mine have ABS light comes on and off. Speedo is good. Had it check by mechanik  drb tool and rear sensor area trouble.   We found twisted wire connection with tape and some corrotion.  I repair the wire that looks like burn and changed othing the sensor but  nothing changed!!   Maybe bad wiring all the way  .   Maybe your trouble???

On some of the Volvos that I work on the Speedo get it's signal from the ABS control module. When the speedo goes out and the ABS light is on I open the module and solder the main power wire coming into the circuit board. You find that the solder joint is bad from the hot/cold cycling.    

New sensor ... no difference

But... Did you ohm the wiring out from ABS unit to the rear sensor?