I'm having an issue with my 1994 Toyota Dlx pickup 4x4 v6. I have tried everything I can think of to try to fix it. I've paid two different mechanics one being Toyota Dealership and one being a mechanic that works exclusively on toyota trucks and 4runners for 35+ years. The issue is knock sensor code we have replaced the wiring harness, the knock sensor 3x, the pigtails twice, and replaced the ecu. The truck runs good for first gear most of the time and even high rpms usually but sometimes the CEL comes on at 2.5k rpm first gear, but every time you switch to 2nd gear the CEL comes on and stays on till you kill and crank it back up. I've spent about 2 grand replacing everything that I know of that has anything to do with knock sensor. Is there anyone that can help me with this problem and knows something that I haven't tried. We have tried OEM knock sensor and bosch.

 

You've done more than I ever have, so this is a shot in the dark. The knock sensor cables are shielded, because the sensor signal is very sensitive to electrical noise. You could check for continuity from the ground side of the pigtail connector (shield should be brown, signal wire black) to a good ground. Wiggle the wire while you're doing that. If you have a bad shield connection to ground, that could result in your problems.

 

Have you considered that the knock sensor might be acting as designed??
Possible that that one or more cylinders might be running lean and knocking??
Carbon deposits on pistons? Unbalanced compression between cylinders?
Valve adjustment, injector service and other fuel delivery maintenance may be in order.
Just spitballin....

 

I don't think that's how the knock sensor CEL works. You get code 53 when "With engine speed between 1,600 rpm – 5,200 rpm, signal from knock sensor is not input to ECM for 6 revolution. (KNK)" The code indicates that the ECM has not heard anything from the knock sensor. Just the opposite of, oh, a low-oil pressure light.

Huh? When you drive your Model T, there is a lever on the column that sets the ignition advance. As you go faster, you advance the timing until you just hear the engine knocking, then back off. Your Toyota (and all "modern" cars) does the same thing. If the ECM can no longer "hear" the knocking as it advances timing, it can't tell if it is advancing so far that you'll blow a hole in a piston. So it substantially retards timing, just to be safe, and throws code 53.

 

Is code 53 the only knock sensor related code??