700R4 Lockup working?

[6.2man]

The lockup feature on my 93 Chevy 1/2T 6.2 4x4 does not seem to be working properly. When I go down the road at a steady 60mph and then gently tap the brake pedal, there is no change in RPM. Any help to diagnose or correct would be appreciated. The cruise control also has quit working. Any connection? TIA

[rhill2901]

The 700r4 relies on the tps on the injection pump for torque converter lockup. You will need an ohmmeter/voltmeter to monitor its operation. With the vehicle in park, and the engine running, check the voltage at the tps. One leg is tied to ground via the transmission so it will read 0 volts. The other leg will read alternator voltage 12+ volts (from the brake switch). Have someone step on the brake pedal and this voltage should go away. If it doesn't, (or the voltage isn't even there) you have a bad stop switch. If it does, then while monitoring the same point, move the accelerator at the pump and see if it drops to 0 volts. If it doesn't, try adjusting your tps. My manual says to set for 8 degrees of throttle movement. My guess is you don't want to have lockup at idle. My tps was acting flaky and I took it apart and cleaned it up with some contact cleaner and it has been working fine ever since. Its only a cam wheel and two tiny springs and some flimsy metal. Be careful if you decide to take it apart.

[rhill2901]

Then of course, all bets all off if your tps is vacuum operated... Your cruise control needs vacuum to operate.