Diesel Place banner

1 - 20 of 22 Posts

·
Registered
Joined
·
119 Posts
Discussion Starter #1
i have been asking allot about this trans. and as a last resort, before taking it to AAMCO to verify that it is toast, can the tps have anything to do with it not shifting out of second gear, what does the tps control on a 6.2? thanks
 

·
Registered
Joined
·
195 Posts
sirk798;1594599; said:
i have been asking allot about this trans. and as a last resort, before taking it to AAMCO to verify that it is toast, can the tps have anything to do with it not shifting out of second gear, what does the tps control on a 6.2? thanks
I had a failed TPS and it was not allowing the torq converter to lockup.

It does control shift points to some degree and it can be checked. do a search on tps and you will find how to check it.

make sure it is a TPSensor not a TPswitch.

The TPSensor it a variable resistor and the TPSwitch is not more than a switch.
 

·
Registered
Joined
·
119 Posts
Discussion Starter #3
lol, lucky for me, i manage a sutozone, so i ordered one in, and am going to hang it tonight, in the 7 degree temps, and see if it fixes it, if not, just return it :D, i suspected it did have some, but limited control in shifting and lock up... jsut didnt want waste time outside freezing for nothing.....
 

·
Registered
Joined
·
6,412 Posts
There is no TPS on a 6.2 with a 700R4... There is one on a 6.2 with a 4L60E. Basically, it is a substitute for the TV cable on the 700R4. It shouldn't prevent the transmission from shifting out of 2nd although it can change the shift points quite a bit.

Have you tried trying to get it to shift at different throttle positions?

Does it stay solidly in second or does it go into third but slip and race and just sound like it is in second? That's what happened to my second 700... I stepped on the gas pulling out of the driveway one day and it wouldn't upshift (or so I thought)... After carefully looking it over I figured out it was, in fact, shifting, but there was no third gear there to go into so the engine was just racing like it was still in second... :eek:
 

·
Registered
Joined
·
119 Posts
Discussion Starter #5
well i can tell you, there IS a tps, AND I BELIEVE a tv cable, on the oposite side, and i know it is a 700r4, and it does shift from 1-2 and in 2, the engine just races all to hell, and tops out at 30 mph or so
 

·
Registered
Joined
·
6,412 Posts
All right then, I suppose there is a TPS... Sorry about that. I was thinking of the Throttle Position Sensor, not the Throttle Position Switch.

In that case, all it does is disengage the torque converter lockup when you let off the gas. The TV cable varies the shift points with throttle position.
 

·
Registered
Joined
·
6,412 Posts
By the way, it sounds like your tranny is doing exactly what mine did when it cooked...
 

·
Registered
Joined
·
6,412 Posts
Hmmm. Not really, actually... The tranny will actually function just fine without a TPS, but it will "jerk" when you let off the gas at speed...
 

·
Registered
Joined
·
119 Posts
Discussion Starter #10
High Sierra 2500;1594639; said:
By the way, it sounds like your tranny is doing exactly what mine did when it cooked...

ya, i am pretty sure it is toast, part that makes me think it might not be, is that just one day, it wouldn't shift, no slipping prior, no anything,, ya i know that can happen, but it isn't the norm.... and if it is toast, am getting a built bullet proof trans for 1,000.00 with a 3 year, unlimited war. so won't be all that bad...
 

·
Registered
Joined
·
6,412 Posts
No, it isn't exactly normal, but it does happen.

There are a couple of other things that could cause the problem... For example, if there was something wrong with the governor (although I think that would affect the 1-2 shift as well) or if there was a problem with the valve body (stuck valve)...

That does sound like a good deal for a rebuilt tranny, though... :cool:
 

·
Registered
Joined
·
195 Posts
High Sierra 2500;1594622; said:
There is no TPS on a 6.2 with a 700R4... There is one on a 6.2 with a 4L60E. Basically, it is a substitute for the TV cable on the 700R4. It shouldn't prevent the transmission from shifting out of 2nd although it can change the shift points quite a bit.
HS2500,

I have a 700R4 transmission and a Throttle Position Sensor as well as a TV cable. I do not disagree with you that the older ones have just a switch but my 91 has a sensor and a transmission control module. I know it is a 700r4 because I just replaced it last summer. I know mine is a Sensor because I had to replace it. $200 :eek: You can access my computer to get a throttle % open. Mine was reading 70% at idle and no adjustment made any difference. I have seen the Switch and it is completely different than what I have.

Just thought you should know.
 

·
Registered
Joined
·
6,412 Posts
HS2500,

I have a 700R4 transmission and a Throttle Position Sensor as well as a TV cable. I do not disagree with you that the older ones have just a switch but my 91 has a sensor and a transmission control module. I know it is a 700r4 because I just replaced it last summer. I know mine is a Sensor because I had to replace it. $200 You can access my computer to get a throttle % open. Mine was reading 70% at idle and no adjustment made any difference. I have seen the Switch and it is completely different than what I have.

Just thought you should know.
As I recall any 700R4 with a true sensor should technically be a 4L60E (which is the tranny a '91 should have anyway) and shouldn't have a TV cable unless it was replaced with a true 700R4 from an earlier truck at some point (this might be the case with yours)... Are you sure it's the original tranny?

EDIT: I'm not saying it can't be, it's just that the setup on your truck doesn't sound 100% original (although it could be, I don't know)...
 

·
Registered
Joined
·
130 Posts
sirk798;1594652; said:
ya, i am pretty sure it is toast, part that makes me think it might not be, is that just one day, it wouldn't shift, no slipping prior, no anything,, ya i know that can happen, but it isn't the norm.... and if it is toast, am getting a built bullet proof trans for 1,000.00 with a 3 year, unlimited war. so won't be all that bad...
its cooked. it was probably something stupid like a TV out of adjustment or disconnected...but the wacky shifts have burnt up 3rd.

i had the same thing happen to me in a borrowed trans-am...90 miles to home at 30mph to keep it in 2nd...that was a hoot! i got him a new 700r4 but he is responsible for installing it :p:
 

·
Registered
Joined
·
119 Posts
Discussion Starter #15
so then, heres the question of the day, how do you properly install the tv cable and adjust it... man i wish i had taken a trans class in tech school, lol
 

·
Registered
Joined
·
6,412 Posts
It's pretty simple. If you want you can even do it without dropping the pan.

On the transmission end of things, it goes into the transmission from the above on the passenger side. There is a hook on the end of the linkage. That hooks up to the TV cable. The cable housing is held down to the transmission by a small bolt.

The cable housing snaps into a bracket behind the injection pump. The cable connects to the injection pump throttle shaft.

It's pretty simple to adjust as well. On the bracket where the cable housing snaps in there is an adjustment. It is sort of a self adjuster... Once the cable is installed you push the little plastic button on the adjuster down and hold it and, at the same time, slide the cable housing toward the back of the truck. Release the button and manually open the throttle all the way (grab the injection pump throttle shaft and turn it until it stops). You should hear a "click" from the adjuster, which means you're done with the cable adjustment... :)

EDIT: By the way, there's nothing about fixing one of these transmissions that a person with average mechanical abilities couldn't handle if they are willing to work carefully and buy plenty of parts...
 

·
Registered
Joined
·
195 Posts
High Sierra 2500;1594722; said:
As I recall any 700R4 with a true sensor should technically be a 4L60E (which is the tranny a '91 should have anyway) and shouldn't have a TV cable unless it was replaced with a true 700R4 from an earlier truck at some point (this might be the case with yours)... Are you sure it's the original tranny?

EDIT: I'm not saying it can't be, it's just that the setup on your truck doesn't sound 100% original (although it could be, I don't know)...
You could be right. I do not know the transmission history of this truck before 75000 miles. The last tranny lasted from then till 300000 miles.
 

·
Registered
Joined
·
877 Posts
High Sierra 2500;1594722; said:
As I recall any 700R4 with a true sensor should technically be a 4L60E (which is the tranny a '91 should have anyway) and shouldn't have a TV cable unless it was replaced with a true 700R4 from an earlier truck at some point (this might be the case with yours)... Are you sure it's the original tranny?

EDIT: I'm not saying it can't be, it's just that the setup on your truck doesn't sound 100% original (although it could be, I don't know)...
Technically, the other fella is right, his truck IS equipped with a TPSensor.

The later 88+ 700R4's have the TC lockup controlled by the TPS but not entirely, it works hand-in-hand with the PCM that's onboard.

Yeah computers on a 6.2, it did happen, but only for the 700R4 6.2's and 4L80E 6.2's, and mostly seen on Vin-C engines with EGR.

The TPSwitch was used up to '87, and does exactly what it sounds like, switches the ability to lock the TC on and off, as well as EGR runction on EGR equipped engines (extra wires). For TC lockup, the two-prong connector is the only one used. With the TPSwitch dis-connected or malfunctioning, you just don't get lockup (open connection), stuck switch, jerky at stop, may kill engine, but only if the brake switch module has ALSO failed (two switches on truck).

The 4L60E was first used in '92 and only has the TPSensor and has no TV cable.

So...

TV Cable and 88+, it's a 700R4.

No TV cable = 4L60E, or... 4L80E (starting in '91 3/4 ton up).

:)
 

·
Registered
Joined
·
6,412 Posts
Learn something every day... I never knew that. Thanks for the info! :)
 
1 - 20 of 22 Posts
Top