Hi All,
I'm having trouble with the left rear wheel sensor in a 95 X300. I had the rear hub assy replaced with a rebuilt unit because the bearings were seized and destroyed the hub. With the rebuilt hub installed, I get a ABS-Traction-Engine light fail indicator. And the Speedo does not work. I checked the sensor (at the connector under the rear seat) and it reads 1.1K per the JAG troubleshoot guide. I remove it from the hub, cleaned, installed, still no luck. I purchased another one just to make sure...same reading. I plugged it in just to make sure (but not mounted in hub) and still no luck. Not sure where to go from here. Hard to believe a the fault is up front in the control box, when all that was done is remove and replace at the hub. HELP.

 

So this is what I found. No problem with connector. I then removed the multi connector at the ABS/Trac control box. All 4 sensors measure the same 1.1K. I cleaned contacts on both the box and multi connector and reattached. Still no Speedo, abs fail...etc. So I thought I would verify that the LHR sensor was any good. I attached the RHR sensor to the LHR connector. Now the speedo works. So if I'm thinking correctly, that tells me the wiring from under the seat connector to the control box is good, and the control box itself is good (or I would not have SPEEDO). Does that sound correct? Is it still possible that even though the LHR sensor measures OK-at the under seat connector-it must be bad? Still could be the sensor wheel, but that was cleaned as part of the hub/bearing rebuilt assembly. HELP STILL REQUIRED!!!

 

Try looking under the rear seat cushion. The connector from the LHS wheel sensor to the loom sits EXACTLY under part of the seat spring. I had the fault every time a passenger sat in the back seat, and the seat spring pushed against the connector, just breaking the connection. Must have been a design fluke that they matched up like this, and you can see from the area around the connection that Jaguar tried to protect/ cushion the connector.

 

It did not work with or without seat installed. I cut off the connector, plugged in the RHR sensor, soldered wires from the connector to the bare wires for the LHR, and that was how I got the Speedo to work. Still looks like the LHR sensor that measured OK at the connector (under the seat)and up at the multi-connector at the ABS box is at fault. I was asking if my troubleshooting makes sense (abs box, wiring to it, and connector are ok)? As stated- I have not yet cleaned the sensor wheel, but it is part of a new rebuilt hub assy and sure looked clean to me when it was installed. How clean do they need to be?

 

Update...cleaned sensor wheel, no change. PLEASE MORE HELP NEEDED. Please read above posts. I want to verify if the wiring from the rear seat to the ABS/TRAC box is good (speedo works when attached to right wheel sensor, but not when attached to left wheel senor, which is the stock set up). If it works THIS WAY (attached to right wheel sensor)THE WIRING HAS TO BE GOOD?

 

I became confused while reading your posts, not your fault, I'm sure. If the cable connected to the LHR sensor has a break, it may make contact when stationary, but open intermittently when the car is moving. Did the various swaps you made cover that possibility?

 

Yes, I would say based on your testing that the wiring from the seat to the control unit is good and the control unit is good.

It all points to a bad sensor to me. A bad resistance reading means a bad sensor but a good resistance reading doesn't mean a good sensor. Ideally you need some live data from the sensor in operation from a diagnostic tool or from a scope to confirm good or bad.

I don't know if it is possible to swap the sensors left and right for testing? They should fit but the cable will point the wrong way. Should be able to get them connected on a temporary basis for testing but the ECU may think you are going backwards.

 

I'm so confused at this point I don't blame you. Not intermittent-totally bad. NO ABS, TRAC, SPEEDO, ENGINE LIGHT ON. NO CRUISE CONTROL.

The only way I could get the speedo to work and to verify if the LH wiring from under the rear seat to the ABS/TRAC box is ok, was to cut the connector off of the LH wire (which was connected to the LH sensor) and connect it to the RH sensor with long jumper wires. SPEEDO WORKS.

I just wanted someone to verify my logic...if the LH wiring going to the ABS/TRAC box was NO GOOD, I would NOT GET the speedo to work at all. It does work when connected to the RH sensor.

The ABS/TRAC still shows a failure because all 4 sensors are not connected (the LHR).

The LHR sensor checks good with a meter at the under seat connector, and when connected, checks good at the ABS/TRAC box connector. Sensor wheel was just cleaned (not easy-tooth by tooth). All connectors and pins cleaned.

I purchased a second sensor and it measures the same as the one installed (but have not installed it)? So??? Can the installed one measure good and still be bad???

This all started when the LHR hub-bearing assembly was replaced.

 

The fact that it happened after the bearing job is what made me wonder about the cable in the wheel well. I do know from checking my own cars that if you turn the wheel slowly by hand you can see the change in resistance in the meter. Not an oscilloscope, but still a good check. Also have some one flex the wire in the wheel well while you watch the resistance.

 

I think the reluctor (toothed wheel) in the hub assy is not turning or MISSING??????
You need to verify that the part is not broken or separated. It is part of the hub seal flange.

Sometimes the collar and toothed assy come apart!!!!!

I have several BROKEN ones in my pile-o-parts. (I'll sell them CHEAP)

bob gauff

 

Bob,
I cleaned the sensor wheel tooth by tooth (see above), and it rotated as I turned the wheel. So I know it's there and rotates. The hub/bearing/seals assembly was purchased from a gentleman in England who rebuilds these, so it was as new and working. I inspected it before it was installed (by a shop I totally trust and they told me I needed a sensor).
Last night I switched out the sensor with a used one (from eBay) and still not working. I do not have a scope and my meter did not show any change when wheel was rotated? Could not turn well? Maybe my meter is to cheap? I have no idea if the used one was any good, (been burnt on eBay before) but it measures 1.1K ohm-like the one I removed?
So I need to either pay $$$ for a new one from JAG or find someone who I can trust to sell me a known good sensor. ANY IDEAS?

 

Hi All
Another question. Looking at the parts list diagram, it looks like the sensor wheel (reluctor) gets installed on the hub assembly. Bob says it is part of the hub seal flange (inner seal?). Does it get pressed on? Is it possible it would turn with the wheel hub at slow speed (by hand) but not when driving? I'm beginning to wonder if it was rebuilt correctly. I can't say I inspected it to see if it was loose. Also the shop did not catch it?
Also here's a electrical question. Are the wheel (hall) sensors polarized? If so why would the speedo work, if I connected the LH wiring to the RH wheel sensor? Wouldn't it be running backwards (unless the SPEEDO circuit does not care). The reason I ask, is I might try to put the RH sensor in the LH wheel and see if it works. IF it doesn't then I know for sure I have a bad/loose sensor wheel.

 

The sensors COUNT TEETH!!!! Number and RATE!!!! That is all. The sensors and reluctors don't care about direction.

The inner seal flange/reluctor wheel unit is TRAPPED between the inner bearing and axle shaft. It rotates at the same rate as the axle. It is part of the spacer arrangement.

bob gauff

 

Bob,
Thanks for the info. Verifies what I thought. Did not know how the sensor wheel attached. The rebuilder said this hub would fit X300, X305, X308. Is there a difference in sensors (depth length) between all these models? I know some are metal, some plastic and some with removable cables? Hope to give it another go this weekend. Thanks

 

Well, I finally fixed it. After talking with the gentleman I got the rebuilt hub assy from, the sensor was mounted 90 degrees out. I had to drill and tap a new center hole (hub only had L and R hole). Wished I had seen the stock positioning, but a local shop did all the original hub/bearings/sensor replacement. The only ting left is how do I get the check engine light to go off?