Toyota Repair: ECU, knock sensor, toyota dealer

Question
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Followup To
Question -
Ted,
I recently had my "check engine" light go on, in my 91 V6 4runner. I scanned the ECU and discovered that the knock sensor/circuitry was acting up (code 52). I took it to a shop where they confirmed the knock sensor was, indeed, the problem and I told them to go ahead and replace it. After they replaced the sensor, I got a call from the shop and they told me my ECU is now bad. They said they could replace it for $400.00. I told them to replace it, and they called me the next day telling me the new ECU is also acting up. I doubted the ECU was bad initially, but now I'm convinced that the ECU was not the problem. Would you know what could be causing the ECU to malfunction ?

Thanks,
Answer -
If the ecu was replaced and the problem is still there it's pretty obvious it was not the problem.
When the knock sensor was replaced was the connecting wire also replaced? Something doesn't sound right.
I would refuse to pay for the ECU because it was a misdiagnosis, tell them to remove it and install your original ecu, then I would advise you to contact a toyota dealer and have the problem diagnosed.

Ted,

Thank you for your quick response. In answer to your question, yes the wiring from the ECU to the knock sensor was replaced. Could this be what's causing the problem ?

Thanks again,

Answer
Make sure that the knock sensor wire was replaced, it connects the sensor to the wiring harness near the intake manifold, make sure it is connected, I have seen this connector not plugged in causing the check engine light. If this wire was not replaced it should be replaced at this time.