ABS Light on, speedometer malfunctioning, OD light flashing, AND harsh or no downshifting - All-in-one!!!

[glacierlily]

So, my 1999 Ford Ranger has the ABS light on constantly. Today, the speedometer would drop to zero every now and then. Then while that was happening, it revved to 5K on a downshift! And then right during all that, the overdrive light started flashing. I stopped the truck, turned it off. Things were better, but the shifting was harsh and the speedometer kept dropping to zero now and then. No check engine was on. After getting back home, using a crude scan tool, code P0500 shows up, and still no check engine light on. The code reader manual says "Veh. Speed Sensor A Malfunction". Where exactly is this sensor and can I change it myself? Automatic transmission, 133,000 miles, 6 cylinder, 3.0 liter, 2-wheel drive. Any advise or help would be appreciated - thank you!

 

[19Walt93]

Pull the codes, I suspect you have a wheel speed sensor having spasms.

 

[glacierlily]

Pull the codes, I suspect you have a wheel speed sensor having spasms.

Thank you for your quick response!

The only code I get on my scan tool is P0500. Would a better scan tool show more/different codes to help pinpoint the problem? I searched some other threads and they indicate the speed sensor in the rear differential is connected to the ABS light/speed & odometer and possibly cruise control. The ABS light had been coming on intermittently before this all occurred. The two times with the problem of the speedometer dropping to zero have occurred on long trips over 30 miles at highway speeds. Short trips, the speedometer is normal but the ABS light stays on continuously now, when it use to be intermittent.

I had thought the cruise control was not working because when you push the cruise on, no light appears on the dash. Recently I found out that the cruise does work even though the "on" light does not illuminate. When you press the speed "set" button, there is a green light on the dash which reads "speed set".

 

[Dirtman]

If you don't have 4 wheel ABS the only sensor is on the rear differential, the VSS doubles as the ABS sensor. Takes 5 minutes to replace.

Though it could also be a wiring issue, it's common for the VSS wire to get damaged. Worst case scenario the tone ring on the ring gear is fubar. But the VSS is not expensive so I wouldn't hesitate to just replace it after inspecting the wire.

 

[glacierlily]

If you don't have 4 wheel ABS the only sensor is on the rear differential, the VSS doubles as the ABS sensor. Takes 5 minutes to replace.

Though it could also be a wiring issue, it's common for the VSS wire to get damaged. Worst case scenario the tone ring on the ring gear is fubar. But the VSS is not expensive so I wouldn't hesitate to just replace it after inspecting the wire.

Super - thanks - that's the plan starting tomorrow. Starting with the sensor. Appreciate your input!

 

[Uncle Gump]

Just an FYI...

I moved this post over to the brake forum... just trying to keep information where it should be.

 

[scotts90ranger]

The VSS is used for all of the above, so I would put my money on that too... It's a VR sensor, only 2 wires and has a magnet on the tip so if there's any metal shavings in the diff they can accumulate there.

 

[glacierlily]

I just wanted to thank everyone for their help with this matter. Replaced the rear differential speed sensor! The ABS light is off. Now it's time for a road test (once the smoke clears). Thanks again - appreciate it!!! Be safe out there!!!

 

[Dirtman]

I just wanted to thank everyone for their help with this matter. Replaced the rear differential speed sensor! The ABS light is off. Now it's time for a road test (once the smoke clears). Thanks again - appreciate it!!! Be safe out there!!!

Let us know if the transmission issue is also gone...