suprathepeg

So the CEL came on and I get a code 52 - knock sensor.

Thing is its a new KS and wire about 10k miles ago when we put the engine in. The truck is a 3.0 so I don't really wanna go that deep if I don't have to. Is there anything else I should be checking before replacing the KS?

MudHippy

Could also be a faulty ECM, according to the FSM. You should also check the connections at the wiring harness to sensor wire, and the wiring harness to ECM for corrosion and looseness. And test the wiring harness itself for excessive resistance. There's really nothing more to it though I'm afraid. It's either the sensor, the sensor wire, the wiring harness, or the ECM(internal circuitry or corroded terminals/pins, E21 and/or KNK).
http://personal.utulsa.edu/~nathan-b...85diagnosi.pdf

ECM pinout, which should be the same as 89 AFAIK.


If not it's the one in the 93 FSM.
http://personal.utulsa.edu/~nathan-b...86troubles.pdf

More info on Toyota knock sensors: http://autoshop101.com/forms/h38.pdf

cracker_1

More likely than not, it will be the KS wire. Somewhere it has a break or has come unplugged. Had the same code, replaced the KS and the wire. No code now... Either way, I think you are gonna have to dig "deeper"....

suprathepeg

So refresh my memory does the KS wire attach to the harness under the intake?

MudHippy

Just under the throttle body.

Might have a rectangular plug like this one. They started changing from the round type in 89.

bob hennig

nice pics, very helpful good definition Thanks,

suprathepeg

So here's an odd thing.

Recently the temperature rose to close to freezing and the CEL went away, soon as it got really cold again it came back. I haven't been able to test the wiring etc yet but any thoughts?

bob hennig

Check connections, unplug, clean up sand slightly, wd40, and plug back in, sometimes contacts respond to hotter/colder, expansion, contraction issues, wiring breaks can also but try this 1st. If not, dig to sensor and rreplace pigtail. B

bob hennig

I am still having the same problem with a brand new KS and pigtail after engine overhaul, I rewired back to computer and still sets code, I can control set of code by timing at 20 degrees and heavy throttle, no code set, part throttle, bang, code set. Beginning to think aftermarket ks is the problem, looking for a good used one now and will try that approach. Bad location to have to experiment with!!!