you have to short the check connector and then it should be at 10*btdc at 800rpm.

 

Code 52 (no input from knock sensor) will severely retard timing and make your truck run poorly. Normally the ECU advances timing until it just starts getting a knock signal from the sensor, and then retards it slightly for optimum operation.

Code 52 does not mean that the engine is knocking. It means that the ECU is getting no signal from the knock sensor. The ECU relies on the knock sensor to prevent damaging detonation if the timing is advanced too far. If the knock sensor is inoperative, the ECU is flying blind and retards the timing to avoid engine damage, and throws code 52 to let you know.

Based on historical data from this forum, the problem is likely the wiring to the knock sensor, rather than the sensor itself. The sensor is under the plenum, so it's a pain to get at, but essential if you're going to fix this.