TCC Lockup

The lockup on my 1988 K-5 Blazer with the 700-R4 transmission locks up between 50-55mph. My 87 K-10 with the same transmission locks up at 45mph and most of my other trucks that I have had locked up at that speed also. Is there an adjustment to make the lockup come on at 45mph or so? Any info would be appreciated. Thanks in advance, JB

 

Check and Readjust the TV Cable. Its the only adjustment I know of.

 

I'll adjust the TV cable tommorow and hope I can get it to go into OD at around 45. Thanks, JB

 

Lockup is electronicly controlled on the TBI models.I have slightly altered the lockup points by adjusting the TPS on these trucks,as well as TV cable.You might have to live with it or change the computer chip.Lockup is affected by TPS,coolant temp,road speed(VSS)and MAP sensor readings.A couple of springs in the valve body to. If your computer wont allow lockup until 53 mph,adjusting the TV cable or TPS is useless.Most people would be happy to have TCC lockup at 55mph,most chug to much at 40mph in lockup in OD.under light throttle my 89 GMC 2500 will lockup at 31mph in 3rd,shift to OD at 35 mph and stay locked up chugging along at idle speed.<p>----------<br>John D<br>

 

John, Thanks for the info. It seems everything is so complex these days. I was thinking of buying a Sensor Tester to check various sensors. Have you or anyone else had any experience with one? I've heard that you can also use a voltage testor also for the same use as long as it is 10 megaohms. JB

 

I use a Fluke DVOM of all my testing, But what makes you think that you have a sensor going bad? I think that sensor testers are a lot overrated. You can test just about anything with a DVOM.

 

What is a DVOM? JB

 

Digital Volt Ohm Meter. I do a lot of electrical diagnostic work. so I bought a Fluke. which is one of the best brands, But there are some good ones out there for a lot less money.

 

I have one, a SUNPRO. I did nt know you could use it for a sensor tester. I mainly use to test volts, ohms and as a tach. JB