Got a confusing situation with some error messages this morning on my 07 V50 B5254T3 M66 AWD. Got 90% of the way to work no issues; 40mph back roads, 60mph highway, stop lights, traffic. Had to stop a little harder than usual and suddenly the dash lit up.
- ABS light,
- traction control/anti-skid light,
- “red triangle” warning light
- Chassis info light with top message “BRAKE FAILURE STOP SAFELY”
- Parking brake info light (right side of cluster)
And immediately after those lights came up the speedo dropped to zero and the trip clock blanked out. Brakes were still functional and power wasn’t limited as far as I could tell. I was able to accelerate through gears 1-2-3 to keep with the 30mph traffic. Pretty sure it wasn’t limp mode.
Got to work and tried to put it into reverse to park; the reverse lock out solenoid wouldn’t let me. I turned the car off and plugged in my cheap OBD tool, came up with P0503 “Vehicle Speed Sensor” which Alldata translates to ECM-A12B or TCM-0082. It wouldn’t start so I cleared the code and was able to start it no issues. If I hadn’t had to get to work I would’ve tried to look into the DTCs more. I don’t have DICE or VIDA but I do have access to a Snapon scan tool that’s pretty versatile.
I’m not seeing many posts at all on here about this issue. Speed sensor certainly explains the no speedometer/reverse lockout and ABS getting confused and sending errors.
Anyone have any ideas on what to look at? I’m going to check the battery health first. Low voltage to that speed sensor on the transmission would cause an unknown readout from the sensor. My next guess is there’s a connector somewhere that’s corroded/loose. I’ll be under the car tomorrow to redo my coolant system (all new do88 hoses) so that’ll be a good time to check that speed sensor.
For context, here’s a list of possible correlations from the past few weeks:
- ~2 weeks ago I left the city lights on overnight and killed the battery. Jump started and no issues starting over the past few weeks. Immobilizer activated but no issues after cycling the key if I recall correctly.
- I recently put the car up on the lift to rinse off road salt. I made sure to keep the hose on a gentle spray as to not damage anything but it was definitely a thorough rinse. Afterwards I did get a ‘service anti-skid’ message like the DEM had lost connection, but it went away and didn’t come back after one stop-start cycle.
- Last night I took the rear wheels off to check rotor sizes. I could have bumped an ABS sensor out of position but I don’t see how that would cause the speed sensor issues from this morning.
- My brother was in the car this morning and it’s possible he could have kicked a connector underneath the glove box where the CEM is.