I have a 1993 XJ6 ad the speedo stopped working, then it started when i hit a bump in the road and then stooped again. Someone told me there is a sensor in the left rear wheel, that might be the problem. Can anyone help me out here? It would be greatly appreciated.
Thank You

 

+1 I also have the same problem on my XJ6 1993

 

Hi Mike & Ignacio,

On the '93-'94 cars, all the wheel speed sensors connect to the Anti-Lock Brake System ECU, which is mounted on the left inner wheel well in the trunk. But the ABS ECU determines road speed based only on the signal from the front right wheel sensor. As far as I know, the only place this is stated is on page 28 of the 1993 XJ6 Sedan Range Model Year Update manual.

THE ABS ECU sends the road speed signal to the Instrument Pack on a Green wire with a Pink tracer line. The Instrument Pack forwards the signal on to the ECM on a Brown wire (this info comes from the 1993 XJ6 Electrical Guide).

You can check for debris or corrosion on the body of the right front wheel speed sensor and its toothed reluctor ring; clean the sensor's electrical connector with zero-residue electrical contact cleaner spray, allow it to dry, then carefully re-seat the two halves of the connector; and carefully inspect the sensor wiring harnesses for damage.

Also, check the VCM for the FF 68 Diagnostic Trouble Code, which indicates a problem with a road speed sensor circuit or the signal from the ABS ECU to the Instrument Pack. To check, turn the key to Position II (Ignition ON) but do not start the engine. Press the VCM (Vehicle Condition Monitor) button on the trip computer to the right of the steering wheel, and watch for a message in the small display below the speedometer.

Let us know what you find out.

Cheers,

Don

 

Hi Don
My 94 xj6 had the left rear wheel bearings go out and took out the abs sensor on that wheel. I replaced the bearings and races but wasn't able to repair abs sensor. in looking in my haynes manual it said speedo controlled from rear diff sensor. My speedo went out when bearings went out. Hoped you or someone else may have suggestion. I checked and cleaned rf connections to no avail. Wondered if left rear sensor out i know abs out but would that also stop speedo from working? When bearing was going bad the speedo was eratic on way home

 

Hi jimbo,

Haynes is correct about the earlier XJ40s, which had a speedometer sensor on the differential. But the later cars like our '93 and your '94 do not have that sensor. The speedometer receives its signal from the ABS ECU as described in my earlier post.

I honestly don't know if the ABS being out due to the failed LR sensor would cause the speedo to cease operating. Have you checked your VCM for any stored fault codes?

Another possibility that comes to mind is the fuse for the ABS system. Could it have blown when the LR sensor was having problems? Based on the '93/'94 Electrical Guide, it looks like the system is powered from Fuse B9 (30A) in the left hand fuse panel. Without power to the ABS ECU you would have no signal to the speedometer.

Let us know about any codes and the status of the fuse and we'll try to think of other possibilities.

Cheers,

Don

 

Thanks don for your suggestions. I checked fuse and it was good put a new one in anyway just to be sure. Then checked VCM only code was fail 1 fuse i believe but that is my door lock fuse which i pulled because don't want doors locked by accident since i have no key fob or a correct door key.Thanks again I'll keep trying to fix car. At least its driveable by the tach to guess my speed.

 

jimbo,

One other possibility occurs to me - could your front right wheel sensor itself have an issue? It does seem logical that the LR sensor would be the source of your problem since the speedo issues coincided with the wheel bearing failure. You mentioned that you cleaned the RF sensor connections, did you also clean the body of the sensor and the reluctor wheel? It might be worth buying both RL and FR sensors. You can probably find good salvaged ones on ebay.

Also, if you don't already have it, you can download the '93-'94 Electrical Guide here:

http://www.jagrepair.com/images/Auto...ec%20Guide.pdf

If your car is a late '94 there may be a few differences from the manual schematics, but most of it will be correct for your car. You might study the schematics for the ABS system and the Instrument Cluster to see if you find any possible clues to your issues.

Cheers,

Don