Engine/Transmission (1998.5 - 2002) T/C unlock at 100 mph

[JohnBoy5]

Ok so i have a geroend fully built trans with trip disk converter. when i have my programer set to 10 or a high power level and getting on the interstate the t/c will stay locked up until about 90 or 100 mph, once i get to the high speed with will unlock for like 1/2 second the lock back, it does this about 2 or 3 times. if i engage my lock up switch it stays locked. so i am leaning towards some sort of electrical problem.



note1: i just replaced the apps sensor and it still does it

note2: when i have the david navone noise filter installed it does not do it. i just dont like that filter that much. i feel like it drops the voltage coming from the apps too much and is less responsive and the t/c will not unlock when you need it to with this filter.



thanks for the tips in advance!



johnny

 

[Mikey-KE7LBB]

Big ticket for going that fast here!!! The truck and tires are most likely not rated for those kinds of speed and 'should' only be seen on a drag strip!

 

[cerberusiam]

Big ticket for going that fast here!!! The truck and tires are most likely not rated for those kinds of speed and 'should' only be seen on a drag strip!

Sad, terribly sad. All I used to get was the old slow down signal from the super trropers as long as I wasn't being stupid.



There is nothing wrong with the truck at 110 pr even 120 mph, the weight and aero make it pretty stable. Most good E rated tires have a speed rating of 110-120 mph if they are aired correctly. Not much room for mistakes at those speeds though, definitely a wide open spaces no traffic or innocent bystander type scenario.





As for the unlocking, its the PCM doing for whatever reason. Could be APPS position and its programmed for that, or, its just noise in the circuit. If you want to eliminate the noise you have to eliminate the source. Otherwise, the mystery switch works great. Throw th efilter away and address the source to see if that changes the way it behaves.

 

[LSchulz]

Sad, terribly sad. All I used to get was the old slow down signal from the super trropers as long as I wasn't being stupid.

Sorry if you disagree, but going 100 mph on the highway IS stupid (and just plain irresponsible). Look at NHTSA statistics and you'll see how many accidents are the result of going too fast.

 

[Tractorat]

Got my 1961 pontiac ventura up to about 115 one night on the freeway when I was in high school. When the cop went by me like I was standing still, I slowed down quite a bit.



In 1974, I was driving my brand new datsun 260Z thru Nevada. Got that little sucker up to (I think it was) maybe about 115 or more (?). Scared the **** out of me. Never did it again.

 

[cerberusiam]

Sorry if you disagree, but going 100 mph on the highway IS stupid (and just plain irresponsible). Look at NHTSA statistics and you'll see how many accidents are the result of going too fast.

Hmmmm, don't remember stating speeding was the smartest or a responsible thing to do. In fact, I clearly stated just the opposite.



Ah yes, statistics. My absolute favorite discipline. Interpret to substantiate or refute, all depends on the subjective view and context. Oo.



Maybe its interpreting too many statistics that skews interpretation of more meaningful ideas?



Derail over.

 

[JohnBoy5]

lol while i love all the replies does anyone have an idea as to what the problem might be? i do plan to go to the drag strip with the truck and it sure would be nice to have this little thing fixed up... .

 

[cerberusiam]

Yeah, I told you where to start and the probable source(s) in my first post.



If your racing you will want to use the lockup switch anyway so the point is moot.



If you want to fix the TC lock\unlock problem due to noise in the system you need to remove the source, the alternator charge wire and passenger side ground from the harness.

 

[BGlidewell]

I'm glad we kept this out of the kindergarten play yard.
My truck is speed limited @ 250MPH.

 

[Wingate]

I'm glad we kept this out of the kindergarten play yard.

hahaha... thats funny. .



will be interesting to see what the outcome of the electrical issue is. .

 

[JohnBoy5]

ok so i replaced the alternator wire wire this morning. i ran it across the radiator like the wire that ties the 2 batteries to one another. when i went for my road test and was taking the truck to up to 120mph i found it was shifting just like it should.

so heres my question, i have not had a problem for 10 years or 160k on the truck why did it start now? its just confusing to me..... but i am sure some of you are confused about the 120mph also.....

 

[cerberusiam]

Age, alternator not working as cleanly as before, the PCM just not getting as clear a signal. Could be any\all contributing to the differences. Glad its working now.



My speed limiter is set to 150 mph so I am not tempted.

 

[JohnBoy5]

well folks bad news, i thought it was fixed drove it all over town this morning and drove perfect! well as it started getting hot today it started acting up. if anyone knows of anything that could be affect by the heat of the day please let me know. o and its doing it at all different speeds now... .

 

[cerberusiam]

Wonder if you have a bad transducer that is sending invalid temp data to the PCM. Possibly a bad connection on the harness could cause that also. Tough to check that out without a scanner or logger to validate what the PCM is seeing and causing it to unllock.



I assume if you engage the lockup switch it has no issues?

 

[JohnBoy5]

I have a snap on solus scanner, I will hook it up and watch for funky readings. It only does this when I am getting on it

 

[JohnBoy5]

ok folks so i finaly naild it down. i have the t/c lock up switch and od switched installed on my truck. i am not sure why it became a problem but the way i have had it installed for the past 5 years was i pulled the relay and installed the jumper wire. then for the switches they just went to ground. well in an attempt to fix the problem i put the relay back and put a 33 ohm resistor in on the computer side of the switch for both the t/c lock up and the od. i still am not sure WHY it was fine for 5+ years and then all of the suddon it was not but that sure did fix it. thanks for all the help and the many laughs about the 100 mph!



side note: its been working great for a about 2 weeks or so. i am pretty sure that was the problem.

 

[JohnBoy5]

Dang dang dang its back... ok so to refresh, truck is unlocking and locking in a fast motion, its going on at about 45 to 70 mph. i have re wired the signal wire form the apps and the ground on the apps, moved the alt charge wire to run across the radiator with the batter cable that ties the 2 batteries to one another, cleaned all computer cable connetions. i did watch the apps signals on a snap on solas scanner and the seem stable. speed does not seem to be the issue, i do know the computer is telling the tc to unlock and its not the trans it self. i also replaced the apps sensor. i have the speed sensor for the trans and the diff on the way from genos. does anyone have any more ideas for me to look at? the sensors should be here tomorrow. if no one has any more ideas i guess the next thing is a computer????

 

[JohnBoy5]

just to bump this to the top and update the folks folowing this post. it looks like injector #2 is sticking. when i get my injectors back and installed i will update this but i think this was the cause of my problems. has anyone had an issue of the t/c unlocking because of a bad injector?

 

[cerberusiam]

Interesting to see if a bad injector throws enough of a glitch the the PCM thinks it needs to unlock the TC. The PCM has to be reading something it doesn't like, maybe contribution percentage is off and it thinks its an error condition?

 

[JohnBoy5]

thats what i was wondering. the shop that built the injectors ot them back today and i hope to hear more from them. the true test will be when i get them back (i hope nest week soon) and drive it. the skip at lite thottle felt like i wsa running over a small board or something in te road. very small and almost unnoticable. but think about it 70 mph and an injector sticking intermiting might would cause this. the engine suddonly slows then picks back up. thats all i can come up with that could be going on.....