Hello all, so my Lexus RX300 1999 speed gauge stopped reading out of nowhere with no reason I could figure out. I looked into it and found that my car has 2 identical engine speed sensors on the transmission. My error code “PO500” said that it was “speed sensor A” that was not working. Ok so I get the new sensor and replace what I believe is sensor A since I could not find anywhere online which was which. So one sensor is replaced and I take the car for a drive and speedometer still doesn’t work and the error code was the same. This made me think it was the other speed sensor of the 2 so I swapped the pieces putting a working sensor into the second hole. Tried the car again and still no speed read out and same error code. What do I do, does the car mesure speed elsewhere like near my wheels? I have found out that my ABS might be related but my ABS system hasn’t work since I’ve had the car, I don’t believe the sensors or wires are even there. Any help with this is greatly appreciated.
Perhaps there is a problem in wiring.
@g-t
Multimeter read outs on both ports are normal as well
I'm assuming you tried every possible combination of switching around the new sensors and still did not help. Then it's most likely a wiring/electrical issue. Be sure to check the connection pins and look for any frayed wiring.
The problem is not necessarily in the transmission sensors. The problem could be one of the wheel sensors. Because you are not getting an error code for a specific wheel sensor, hook up a scanner that can read live data. Compare the reported speeds from all the wheel sensors. If one reported speed is different that would be the location of your problem.
I had your symptoms. For my car, the problem was a tone ring separated from a hub. Therefor the wheel sensor was reporting bogus speeds. Solution: replace hub.
Wheel speed sensing requires two parts:
- the magnetic pickup (the part you replaced)
- a reluctor ring (inside the transmission)
The sensor is using a magnetic field to pick up bumps on the reluctor ring.
Because these parts are magnetic, they like to pick up bits of metal, which interfere with the speed signal. High mileage transmissions have plenty of those inside. So you sensors might have been fine, but there was too much metal floating around on the ring, and in the gap. Or sometimes the sensors can shift and the gap space is very important.
Another possibility is a fault in the wiring harness.
