94 Transmission Diagnostics

[momses300]

Does anyone out there have recommendations, proceedures, etc for diagnosing slipping and o/d problems on the early (94) es300 ? I've been to the dealer, gotten the "lets replace the whole thing for $3800", have installed a used (60K miles) transmission, and still have the same no overdrive symptoms. Codes I've gotten are P1600-computer battery backup, P0720-output speed sensor, P0500-vehicle speed sonsor, P0100-airflow circuit, P0110-intake air temp. I've been working out of a Haynes manual (97 and later toyota), gotten myself pretty confused, and would like more accurate diagnostic procedures. Does anyone out there have a factory manual that could help ? Mayday...Mayday....any station come in please!!

Bill

[SKperformance]

You have a few problems if you get that many different codes.

I would start by checking the wiring for animals chewing through wires.

[mztrmarcus]

My 1995 ES300 is displaying similar symptoms (no speedometer/odometer reading, O/D lights blinking when O/D should be on, CEL on). OBD test results in codes P0500 and P0720 both of which lead me to suspect the Speed Sensor on the transmission is bad. However, I am having some doubts because I am getting 2 codes instead of just 1. Do these 2 indicate an electrical problem from the sensor the the computer box?

Is there a way to test the Speed Sensor? Can I attach it to a drill and spin the gear to check if it's working? The sensor costs somewhere in the neihborhood of $170 off the www and off course they will not accept returns if I find that changing the sensors doesn't fix the problem.

Thanks in advance.

[mztrmarcus]

My 1995 ES300 is displaying similar symptoms (no speedometer/odometer reading, O/D lights blinking when O/D should be on, CEL on). OBD test results in codes P0500 and P0720 both of which lead me to suspect the Speed Sensor on the transmission is bad. However, I am having some doubts because I am getting 2 codes instead of just 1. Do these 2 indicate an electrical problem from the sensor the the computer box?

Is there a way to test the Speed Sensor? Can I attach it to a drill and spin the gear to check if it's working? The sensor costs somewhere in the neihborhood of $170 off the www and off course they will not accept returns if I find that changing the sensors doesn't fix the problem.

Thanks in advance.

I found a way to test the speed sensor by back probing the connectors and turning the wheel which should result in a change of voltage between 0 to 11 volts. I found that my sensor is in fact busted so I called Lexus for a replacement part. Glendale Lexus said they had it in stock so I went there to pick it up. When I got there, the part that they were giving me was totally different. They had part number 89413 which was a black plastic sensor which had a diameter smaller than mine (physically not substitutable from the original). So I showed them a picture of my speed sensor (taken from the part manufacturer's website: http://www.smpcorp.com/web_app/catalog/smp_bgbulk.aspx) part number SC149. They said this part is superceded with the new one. Duh?

Anyone have information on the part number I am looking for?

Thanks in advance.

[cldriscoll]

i have error codes p0500 and p0720. I work at a major motor parts warehouse and the guys in the showroom narrowed it down to needing a standard sc149 or sc153, but im stuck with a 50/50 chance of wasting $100 or $200.