Allright y'all...
I recently refreshed a 3VZE engine back to it's glory days. The engine is a good engine giving me about 170psi per cylinder when I test compression. Good engine.

When I purchased the truck there had been a fire in the engine bay and the wiring harness was charred. Luckily I was able to drive it home but I knew I would have to replace the harness. Before removing the harness I checked error codes and was only getting code 52 with the damaged harness. When I tore in to it, I replaced the harness with a good harness that I pulled from the salvage yard. To me it was a good harness because it was not spliced, was not brittle, and all the connectors were there. While I had the engine open, I bought 2 knock sensors and 2 pigtails by accident. I meant to order only 1 set. While there I did the timing belt, water pump, tensioner, distributor, spark plugs and spark plug cables. After I put it back together and fired it up I got the dreaded code 52 again. Having and extra set of k ock sensor and pigtail, I tried the other method common in these forums of installing on the hook attached to the head of the engine. After completing this mod, I am still getting code 52. I have purchased the ATS Racing adaptor for the MR2 as noted in another thread here. I will let you know how it goes. Before I do the GM knock sensor mod though, I am going to run some tests on the pinouts to the ecu, for the knock sensor. If the pinouts test good, I will consider replacing the ecu before I do the ATS gm adaptor. I read on another post that someone resolved code 52 by making repairs to the ECU. I don't know what to test and how to test it, but I can rule out a bad ECU by doing a final test on the new wiring harness.

​​​​​​MY theory is that when the old harness burned and the wires became exposed, they shorted and caused damage to the ecu. I will keep you all updated on this post incase any of you also face this issue. I will include a more cohesive write up with pics.



Her name is Eleanor, my 89 Toyota Pickup dually with free floating axle, 6lugs and utility bed. This truck is so damn awesome can't wait to get it on the road again. Will post pics of Eleanor.

 

I'd think if you shorted the ecu and damaged it you'd be throwing a lot more codes, not just a 52.
Where did you get the knock sensor and wire from?