Hi all,

I'm working on my girlfriend's daughter's car. It's a '98 2.3 cl, auto trans. The transmission was recently rebuilt, and I have the cylinder head off to get a probable leaking exhaust valve on #1 fixed. (a leakdown test had that one blowing air into the intake manifold.)

Anyway, the speedometer works intermittently. It does not default to 20 mph like I read about on the internet a lot, it simply drops to zero. I suspect that one of the speed sensors might be bad, but I don't want to go replacing sensors without checking to see that it's not a simple bad ground or something. The haynes manual I got on the same year accord shows a different sensor, one with a gear. The ones on this car are much smaller, and located more to the passenger side of the transmission. The test procedure it outlines also mentions checking for the 5v reference voltage on a wire of a color that does not go to the sensors on this car. So, I can only assume that an accord does not use exactly the same sensor as this acura.

If any of you have an appropriate procedure for testing the speed sensor(s) on this car I sure would appreciate it. I don't have an oscilloscope, but I do have a basic digital voltmeter and some electrical skills.

 

i've never heard of this problem on a cl? maybe i will talk with my mechanic freind to see if he can help you.

any else hear of this bad issues?

 

Ok folks, I have an update. Here's what I've done:

There are apparently two speed sensors on the transmission of this car. One is on top, towards the right, pretty much under the air duct from the filter box to the throttle body. It's a simple magnetic pickup that plugs into the transmission with an o-ring, and it's retained by a 10mm bolt. The other one is almost identical, the only difference I can see being that the place for the retainer bolt is on the opposite side of the sensor body from the top one. This one is located on the front of the transmission, toward the right, and it's kinda a bitch to get to.

I have access to scan tool. I hooked it up, and to my surprise I found that the computer is in fact getting a speed reading all the time the car is moving, even when the speedometer is resting on zero. So, I unplugged the sensor on the front. It continued to get a speed reading, and it set a code that says something about incorrect gear ratio. I plugged that one back in and cleared the code. I then unplugged the top sensor, which is the one I had suspected was the problem. The computer lost it's speed input, and set another code. I forget what this one said, but it was something typical for what I'd expect to see if you removed the speed input the computer needs to make shifting decisions. Sure enough, the D4 light began flashing too. So, I plugged that one back in and cleared the code. The computer is happy again, but the speedometer continues to read intermittently. I tried tapping on and around the instrument cluster with a flashlight. It does not seem to affect the behavior of the speedometer-it continues to jump around between whatever speed the axles are turning at and zero. I also carefully examined the wiring going to the top sensor, and I can see where one of the wires going to the sensor changes color before it gets there. I peeled back the protective sheath to see why, and it appears that the wire that changes color is shielded, and the shielding ends. As you come from the wire harness toward the sensor plug, the big part of the wire (I think that's pink) ends, and the little green part comes out of the center of that and keeps going to the sensor plug. At the part where the pink ends, you can see a layer of medal braid that obviously covers the small wire and it's insulation when the small wire is inside the big wire. Clear as mud?

I have had the car on jackstands with the front wheels removed to do these tests. I have left it that way so that if you guys can come up with anything, I can quickly run out there and try it. I'm game for almost anything at this point.

 

you have an appropriate procedure for testing the speed sensor(s) on this car I sure would appreciate it. I don't have an oscilloscope, but I do have a basic digital voltmeter and some electrical skills.





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