You can run a 700R4 without lockup, although without the lockup, the 700R4 transmission will run and the life of the fluid will also be shortened as well as the transmission life will be shortened.
The 700R4 transmission an be run without the lockup function connected, although it's not recommended, especially for extended highway driving as without the lockup, the 700R4 transmission will create excessive heat and suffer from reduced fuel economy and will also be more prone to burning the fluid or internal components.
When you run the 700R4 in overdrive without the torque converter locking up, it causes your torque converter to constantly slip, which generates severe heat and the excessive heat will cook the transmission fluid and eventually lead to burnt clutches or complete transmission failure.
The lockup also provide a direct mechanical link between your engine and your transmission, which also lowers your RPMs at highway speeds and saves fuel as well.
The unlocked operation of the 700R4 transmission means that you lose this efficiency as well as risk damaging your transmission.
If you do run your 700R4 transmission without lockup, you should stay in 3rd gear and avoid using overdrive (4th gear) on the highway and most people suggest you leave the transmission in 3rd gear for in town driving to prevent the continuous slipping that is associated with unlocked OD.
And install a high quality aftermarket transmission fluid cooler as the heat is the number 1 killer of automatic transmissions and a dedicated cooler is crucial if you're not engaging lockup.
A 700R4 transmission will also not shift properly without the TV cable and will burn up the very quickly.
Driving without the TV cable on the 700R4 transmission will cause the transmission to have early and weak shifts and severe slipping, which will quickly destroy the 700R4 transmission in a matter of a few miles or less.
The TV cable is required for the 700R4 transmission to shift properly as the TV cable mechanically regulates the internal hydraulic line pressure that is based on the throttle position.
Unlike older transmissions that use engine vacuum, the 700R4 transmission relies on the TV cable to determine how much line pressure is needed and more throttle = more pressure and less throttle = less pressure.
Without the TV cable indicating throttle position, the 700R4 transmission will not known when to command the shifts and result in erratic and extremely early shifts and no passing gear.
And low line pressure that is caused by a disconnected or loose cable allows the internal clutches and bands in the 700R4 transmission to slip, which creates immense heat and rapidly burns the transmission up.
The only way that you can operate a 700R4 transmission without a standard TV cable is if you install a specialized Constant Pressure Valve Body or a Constant Pressure System such as those from TCI, which are aftermarket modifications that allow your transmission to maintain adequate line pressure without a cable, although the shift timing might still require being managed manually.
The common problems that the 700R4 transmission have are delayed shifting or hard shifting as well as slipping gears and sometimes total transmission failure.
These common issues with the 700R4 transmission, which was later known as the 4L60 transmission are often caused by fluid loss, inadequate cooling and even a misadjusted Throttle valve cable also known as the TV cable.
The 700R4 transmissions TV cable or throttle valve cable is what determines the transmission line pressure that is based on the engine load.
If the transmission TV cable is stretched or misadjusted or is installed with the wrong geometry on aftermarket carburetors, the 700R4 transmission will burn up the internal clutches very quickly and so it's important to make sure the TV cable for the 700R4 transmission is adjusted correctly and installed correctly.
Ensure that the TV or transmission valve cable is properly calibrated using the manufacturer's specified procedure to align the throttle position with the transmission line pressure.
The slipping gears and momentary surging that can occur with the 700R4 transmission is a common issue with the 700R4 transmission and includes, slipping, especially when the transmission is cold, or a failure to shift into 2nd or 3rd gear and often points to low transmission fluid or a clogged filter.
The fluid loss with the 700R4 transmission often occurs at the torque converter seal or tailshaft seal.
You should check the transmission fluid on level ground while the engine is running and warm and top it off and replace any leaking seals.
Loss of reverse gear and overheating are also common with the 700R4 transmission, especially when not maintained properly or when you do a lot of towing.
Losing reverse or having difficulty in engaging into neutral is a widespread issue with the 700R4 transmission that stems from internal wear, worn reverse clutches or low fluid pressure due to case leaks.
You should inspect the tailshaft for leaks and verify fluid levels, if the fluid is full, the transmission may require a teardown to inspect and replace the worn reverse bands or clutches.
And operating a 700R4 transmission without an adequate transmission cooler frequently leads to burnt fluid and warped internal components.
And so you should ensure your factory transmission cooler is fully functional and consider installing an auxiliary transmission cooler if you use the vehicle for towing or heavy duty hauling.
However, while there are some common issues with the 700R4 transmission, it can be a very reliable transmission if maintained properly and you change the fluid and filter often enough as well as ensure the fluid level doesn't stay low and you don't overheat the transmission or overload it.