ABS Light On

Has anyone experienced no 12 volt power at right rear ABS sensor.
Wiring Diagram and notes stipulate that one of the 2 wires should have battery power.

Left rear does have 12 volt at connector!

Have checked for power in Pin connector on ABS Module and it reads 12 volts so I am suspecting a broken wire between connector under back seat and ABS Pin Connector at Module.

Does anyone have knowledge of any other connectors and or locations?

 

There are no other connectors between the ABS module connector and the ABS sensor connectors under the rear seat.

You may not have a broken wire! The ABS controller continuously range-checks the ABS sensor output signals. If a sensor signal does not fall within the expected range, the ABS controller will automatically turn off the +12V drive signal to that sensor after about 2 seconds. I chased the exact same gremlin in my car! The Jaguar service manual is silent on this tid-bit of very important information. I happened to read about it on some other forum for another car that also uses Bosch ABS.

I would suggest hooking up your voltmeter to measure the voltage between the sensor drive signal wire and chassis ground at the connector under the rear seat while the ignition key is off. After turning the key on, immediately check for voltage (about 11 VDC, if I recall correctly). If the voltage appears for a few seconds then goes away, you may have a bad wheel speed sensor (like me).

I bought a new wheel speed sensor from Auto-Zone for about $62, if I recall, and installed it in 10 minutes. Problem solved!

 

Thank you so much Mark.
I did replace the Sensor initially and the light went out, then came on again a short time later. Maybe the new Sensor is defective or the tone ring is rusted and not generating the pulse properly. I will do some more exploring and let you know!

 

So if I had the right rear connector disconnected under the seat would this simulate a faulty sensor and give me that momentary reading on my voltmeter at this connector? I did the voltage check with this connector uncoupled from the actual Sensor!

Is it possible to test the new Sensor for continuity or is it a Hall Effect item?

 

If the ABS sensor was disconnected, your ABS controller should have flagged this as a bad sensor and turned off the drive voltage. You didn't say if you saw the voltage appear then disappear. What happened?

A continuity test of these ABS sensors isn't helpful; a good sensor will look like an open circuit (it is a Hall-effect device).

 

Mark

There was a momentary flash on the screen, no actual voltage numbers showed. When I first installed the new Sensor the light went out for a short time but returned.

I also was having trouble with the MIL light being on but that related to me changing the battery. This light is still on giving Code P1000 as all monitors have not reset yet.

I assume this would not prevent the ABS from resetting and has no relevance|

 

P1000 will not set a MIL. There's some other problem lurking! Changing the battery should not cause a MIL either. Time to get the codes read again, I would say.

 

My ABS light was usually accompanied with a MIL light. Also, engine RPMs would drop more quickly when getting off the throttle, which sometimes caused stalling when the clutch pedal was depressed - really annoying. When the ABS light cleared (my sensor had intermittent problems), the MIL light would clear shortly thereafter and the engine would then run fine. Not sure why drivability is affected, but it certainly was. The bottom line is fix the ABS issue and the MIL light problem will likely go away too.

It sounds like you may have not had good contact with your meter when you made the voltage measurement. I would suggest measuring the drive voltage on the other (working) rear ABS sensor to verify what you need to do to make good connection to the connector terminal and chassis ground and to determine the drive voltage to a good sensor. Then do the same on the suspected bad sensor.

-Mark