Converter Locking/Unlocking at Speed

[BButkus51]

Yesterday I took my car for a cruise for the first time this year. For the first 10 miles it ran and shifted great. On my way back home when in 4th gear after the converter would lock it would sporadically unlock then lock back up. It would do it 4 or 5 times then stay locked up. The 5 mins later would do the same thing again and so on. Wondering if someone could help me on what to look for? I attached a short video of what it was doing.

Thanks,
Bob

 

[TurboDave]

One possibility could be the brake switch down under the dash could be mis-adjusted. Might need to be adjusted just a little closer to the brake pedal.

 

[GSP]

Yeah what Dave said... or it could be the TCC.. the solenoid that makes the converter lock... it was a little of both on my car at 120k.. easy to do, cheap and it gives ya an excuse to change the fluid and filter..

 

[TurboBob]

I had a bad gear switch in the trans do that as well.

Bob

 

[jpratt]

Had a similar thing happen to mine and it wound up being a bad TPS connector at the switch. Power logger showed idle the 1.47 then idle again real fast like the go pedal was being drummed on.

 

[TurboDave]

Had a similar thing happen to mine and it wound up being a bad TPS connector at the switch. Power logger showed idle the 1.47 then idle again real fast like the go pedal was being drummed on.

Hmmm you just reminded me of a similar problem I had about 8 or so years ago. Mine was doing the same thing, and never had any luck catching it on Scanmaster back then. So I hooked up my Direct Scan back then and it was finally able to capture the problem thanks to it's 20 second buffer (like what Powerlogger now has). It caught my TPS dropping out for short milisecond intervals.

 

[BButkus51]

Thanks for the answers everyone. After reading the possible causes I think I will go take the car for a drive again with Direct Scan running and see what it is saying. If it is something with the switch the TCC should show the computer calling for it to lock and unlock. It it just says locked in DS I should look to the solenoid. Does that sound like I am on the right track?

 

[Thumper]

What is your coolant tempertures when this is happening?

 

[haywire4130]

What is your coolant tempertures when this is happening?

hahaha beat me to it... if your thermostat is sticking or you're not running one it will do this. i forget the exact temp (i believe 150) but it will lock when it hits this temp, then if it cools below that it will unlock, then back and forth. happened on my old s-10 blazer years ago.

 

[BButkus51]

hahaha beat me to it... if your thermostat is sticking or you're not running one it will do this. i forget the exact temp (i believe 150) but it will lock when it hits this temp, then if it cools below that it will unlock, then back and forth. happened on my old s-10 blazer years ago.

I thought it was around 170 but not 100% positive. I need to get the laptop out and take a drive and get some data. Thanks for the heads up as I had no idea that that could cause that. Really appreciate it.

I will get the car out soon and post any results I get. Thanks again to everyone for the help!

Bob

 

[TurboBuRick]

Sounds like o.d. solenoid is on the fritz. Not a hard job to replace though you do have to drop the pan and that can be messy.

RL

 

[haywire4130]

I thought it was around 170 but not 100% positive. I need to get the laptop out and take a drive and get some data. Thanks for the heads up as I had no idea that that could cause that. Really appreciate it.

I will get the car out soon and post any results I get. Thanks again to everyone for the help!

Bob

Definately below 170, as most are running 160 t-stats. I could look it up in alldata if youd like but it could vary depending on whose chip youre running and how they programmed it. Im not certain it's your problem, but its worth looking into the brake light switch is another definate possibility as mentioned above, as well as a chafed/loose wire.

 

[trbojo]

i'd have to go with tps dropout.....

 

[NarcGN]

I just unplugged the cable going to the TCC. Trans shifted great. I dont need to worry about fixing it now since i went with a full billet CK.

 

[we4Mateo]

I just unplugged the cable going to the TCC. Trans shifted great. I dont need to worry about fixing it now since i went with a full billet CK.

I thought it was a bad idea to run a LU TC unlocked all the time?

 

[NarcGN]

I have no idea, seemed to work ok.. I only did it cause i was changing my stock trans with a CK one and PTC 3400 non lock up.. and didnt feel like changing the TCC valve

 

[BButkus51]

I finally had time to get the car out for a cruise. I loaded to Direct Scan and went for a 30-35 min drive and could not get it to unlock one time. It drove perfectly. Now I really have no idea...