Code E024 popped up again

[Ronnie]

I had the Reatta out for a long drive today. After going about two miles down the road, while sitting still waiting for a red light to change, I got a warning message on the Dash and CRT saying Electrical Problem Detected. Engine was running fine.  As soon as the car started moving again the warning message disappeared and everything seemed to be working properly

 

I drove another mile or so and pulled over to check diagnostics for trouble codes.  The only code was a E024 - "Speed Sensor Circuit (TCC)".  I got the code one other time today while sitting still at a red light.  I had driven about 50 miles between the times it happened.   Both times I had been sitting at a red lights longer than usual due to heavy traffic.  It's odd that a speed sensor code would occur when sitting still.

 

I got this same code earlier in the year and I though I had it cured by cleaning the speed sensor connector but I checked it again today and it looks clean as a whistle.  I don't see how a bad speed sensor would cause the problem because it shouldn't be reading anything when the car is sitting still.  Any ideas?

[DAVES89]

Sorry Ronnie no ideas from me.

 However just to show how goofy these cars can be, about a month ago I thought I would try the headlight switch out of my parts car. Worked great and backights are real bright, thought I had a winner. About 2 weeks ago I started getting E026 codes, with B122 ans B123 going to history. I thought it was the light sensor under the dash, but yet the dash lights would dim on the dash. I decided to replace the switch with one from the Reatta I just picked up. 50 mile drive and no codes. Must be the switch.

 Sometimes things trip and you just don't know why. For me it was easy, just swap out the last thing you put in.

[Ronnie]

I'm just glad the code 24 isn't causing any problems with the way the car runs or drives. It's just a random annoyance when the warning pops up on the screen and goes away as soon as the car starts moving. 

 

I've been doing some checking this morning and I think I might have stumbled across the problem. Even though the code is for the speed sensor I don't think that is what is causing the code or the warning that pops up.

 

Before I ever started the car this morning, I was going through the codes in diagnostics to clear them and I noticed the gear indicators on the diagnostics screen were showing that the transmission was in 4th gear. I started the engine and then went back into diagnostics. Still showing 4th gear but when I started driving the 4th gear indicator was gone until the transmission was actually in 4th gear going down the highway as it should be.

 

I believe the the ECM (or BCM?) is seeing the transmission in 4th gear and the speedometer showing 0 MPH when sitting at a red light and knows that's not possible. There must be a delay built into the ECM programming that gives a little time for that condition to change before it throws the code 24 and displays the warning on the CRT. That would account for me only having this problem when sitting still for extended periods of time with the transmission in gear.

 

I think the root of the problem is the 4th gear indicator switch inside the transmission is sticking and giving a signal to the ECM that the transmission is in 4th when it's not.  I don't think I will be taking the side pan off the transmission to change the switch unless it gets to the point where I can't put up with the warning anymore.  It happening randomly doesn't bother me and it's not preventing me from driving the car.  I will add some Seafoam Transtune and see if that helps like someone suggested before.   If the problem gets too bad I will pull the pan on the transmission this winter and install new gear indicator switches. ?

[2seater]

I just got back but I was thinking the same as you; something else was telling the ECM it was in an impossible situation. So glad you sleuthed it out and passed it on.

[Frogware]

Ronnie, just a curious thought - I think I remember you once posting that you wired your TCC plug to a switch so that you could turn it on or off depending on your driving conditions. I am not sure if it would be related but since the code 024 is part of that do you think the ecm is detecting that also? Maybe I am out in left field like I say it was just a thought.

[Ronnie]

Welcome back Scott!

 

As you say, I do have a switch that can be turned off to keep the torque converter from locking. I think the switch was in the normal position when the code 024 occurred.  It still could be related to the switch someway but usually if the switch is in the off position to prevent the converter from locking a code E031 will be set in diagnostics but no warning will appear on the CRT.  I didn't have a code 031 when the code 024 was present.  The next time I get a code 024 I will check to see what position the switch is in. Thanks for the tip!