So I took the quarantine time to do a bunch of things my disco desperately needed, which was a new steering box, new track and drag links, new ball joints, and new fluid in the transfer case and diffs. This morning I went to start it and it did not turn over, so I had to jump start it. The first trip was to get the alignment done, and I noticed that the speedometer was not working. I had no lights on the dash, I just could not tell how fast I was going. I have googled and I am confused, what controls the speedometer?? Is it the sensor in the transmission or one of the wheel speed sensors (which I did have to remove from the hub to do the ball joints)?? Or could it be that I fried something when I jumped started it?

It is a 2004 Disco SE7.

Any help is appreciated.

 

The speed sensor is mounted to the valve block inside the trans, so it's doubtful that you damaged it doing those maintenance items. If the battery was dead this morning, check the batt and the output from the alternator. Low voltage causes all sorts of electrical troubles.

 

Two new pieces of information. I forgot one of the things I did do was pull the dash apart to fix a the light bulb behind the lcd. Could it be that something is unplugged back there?

Today I got a code for P0501 which I know does have something to do with the VSS, but could it because something is unplugged in the dash it triggered the code? Do the ECU reading come from the speedometer to trigger the code for a difference between ABS and the VSS?

Thanks

 

I am still working on this. I now have worked on it and realized that the odometer is not working. I also hooded up my phone OBD reader and while driving it show "0" for speed.

I am thinking of hooking my Foxwell tool up to see if all wheel speed sensors are sending information (is this a dumb idea?). Maybe I broke one during ball joints.

I am also wondering if I fried a fuse on my ECM when I was jump starting it, is this possible? (Is this located behind the glove box?)

Also wondering if maybe when I disconnected my cluster to replace a bulb it lost connection with the ECU, but my research says my odometer would be flashing, and it is not.

Anybody have any idea where to look next? or any insight?

 

Hmm, it doesn't seem your odometer would work if your cluster were not hooked up... Do the warning indicators light up in ignition position number 1? Is the whole cluster dead or just the odo/speedo?

 

Hi Dave thanks for the help,

The cluster is working. I do have a SES light and the tachometer is working. It displays the milage but is not adding milage as I drive. When I put the key in the other lights do light up.

 

So I checked the fuses in my fuse box under the hood and the fuse box by the pedals and all looked good, but today when I started the car up the speedometer worked for a few seconds and then the trip logged .01 miles. This makes me think somewhere I have a fuse issue and it is not the VSS or SLABS unit. Anyone have an idea of which fuse might work this the Speedometer and odometer? The odometer is lit (not blinking) but not adding miles or calculating the trip miles.

Any help is appreciated.

 

Pretty sure there is not a fuse dedicated to just the speedo. If it was working fine before you had the cluster apart, that’s where I would focus. Maybe a damaged wire, or a pin on the terminal. Check all of the traces on the PCB too. I don’t have any first hand experience, but my money’s on the gauge cluster itself.

 

I checked the cluster connections and all look snug and tight. I also scanned the abs unit and am getting codes for all four wheels:

DTC-Front Right Sensor output too low
DTC-Rear left sensor output too low
DTC-Rear Left sensor electrical failure
DTC Rear Left sensor signal erratic
DTC-Front Left sensor signal erratic
DTC-Rear Right sensor signal erratic

This makes me believe I somehow screwed up something with the ABS sensor. My understanding is that the speedometer uses Wheel speed and the VCC from the transmission to indicate speed. So my next question is where is the ABS module? Is this the SLABS unit in the glove box area?? I have heard someway it is in the engine bay? CouldI have blown the unit when I jump started the vehicle?

Thanks for any help

 

Make sure the SLABS unit behind the glove compartment has all the connections fully inserted especially connector C0505 which all the ABS sensors connect to.