Funkdoobiest

iTrader: (1)

I did a little homework here but only found a few topics with these codes. I'm going to be very specific.

My mom's 94 automatic ES was hard shifting. The dogbone was bad, but I replaced it only for it to get ripped apart again by the hard shifting. So I replaced her transmission with a used one because I got a really good deal on one. Now it's worse. The trans shifts very hard in every gear and it has NO O/D. The O/D light flashes. The kickdown cable is adjusted correctly and I put a new filter and fluid. But I DO NOT have an erratic speedometer.

So I pulled codes yesterday and got codes PO500 and PO720. My scanner said PO500 - Speed Sensor A and PO720 - Output Shaft Speed Sensor Circuit.

Now, is each code for each speed sensor? Is there a way to test them individually? Does the letter A represent which speed sensor I need to replace?

Gerson

iTrader: (1)

The main speed sensor is behind the cluster I think. When u replaced the dogbone mount u should of replaced the front engine mount as well to eliminate hard shifts and engine movement. Make sure your connections are not loose or broken.

Funkdoobiest

iTrader: (1)

I read everywhere that there are two speed sensors on the trans itself. A 2-wire and a 3-wire. When you say the front mount, do you mean that front trans strut mount? I have another new dog bone, but I'm not putting it on till the problem is fixed. I replaced 2 mounts when I replaced the trans. The driver side trans mount and that front strut mount. They were both shot. But this is not the problem. I have 2 trans codes, it's very hard shifting, and I'm missing O/D.

llcoolpass

how is the fluid?

Funkdoobiest

iTrader: (1)

Great, brand new fluid, new filter.

llcoolpass

how is the sensor?

Funkdoobiest

iTrader: (1)

I gotta ask. Did you read my post? I stated in it that it has new fluid and I ask how to test the sensors. Yet you asked 2 questions already answered.

GEORGE_JET

Now, is each code for each speed sensor? Is there a way to test them individually? Does the letter A represent which speed sensor I need to replace?[/QUOTE]

Attached is doc to explain these codes. follow their steps and you should get a better idea what is really going on. Do not consider replacing the sensor before you do some tests to isolate the problems.

p720.doc

Funkdoobiest

iTrader: (1)

That's great, exactly what I need. Yeah, I want to diagnose before I start spending more cash. Thanks.

GEORGE_JET

I looked at little at the diagrams for this. You state that the speedometer is working. Is the cruise control working? From what I see, the speed sensor sends the signal to the combination meter (gauges), then to both the ECM and CC. If the CC is working I would start looking at the wiring between the combo meter and ECM

Funkdoobiest

iTrader: (1)

I'll try the CC tomorrow. I hear about the combination meter, but where is it located and what's it look like?

GEORGE_JET

Combination meter, instrument panel, same thing. The manuals lose a little in translation from Japaness

Funkdoobiest

iTrader: (1)

Ok, I checked it all out last night. Things have changed, here's what's going on now. My mom said the Lex has been shifting better so I cleared the codes and took it out for a 20 mile spin. The shifting had improved tremendously, so I installed the dogbone and all is good now as far as hard shifts. The speedo does in fact work fine and so does the CC.

Here are the problems. There is still no overdrive. The O/D light switches on/off but the trans doesn't do anything. The ECT Power light stays on all the time, the switch only slightly dims the light when switched to off. It did this before the trans was replaced too. But the shifting points are high like it's on all the time. No more codes popped up after driving it 20 miles.

llcoolpass

is the overdrive [enable/disable] switch operating properly?

Funkdoobiest

iTrader: (1)

Yes. Also stated above.