Greeting gents, I have a question. Hoping to get some assistance.

I have a 92 Prelude, OBD1, running S300 and looking at a problem. I have a fault code 10, which is an IAT error. I have swapped out the sensor with another that was functional so it's not the sensor. Have a connected Rywire harness and SManager is getting a reading of 123.4 (after doing some driving). No matter how many times I blow out the code, it immediately returns. I am wondering how I can troubleshoot this issue before altering the settings. I am on a basetune from J. Waters and it was fine up until recently. Can someone give me some starting advice on how to blow the code?

Thanks in advance.

 

If the code comes back immediately after clearing it, and you have a "known good" IAT sensor... you have one of three possible issues: 1) The IAT sensor is unplugged or not making contact with the pins at the plug; 2) You have a break/short in one of the two wires between the sensor and the ECU; and 3) You have a bad IAT circuit in the ECU (the ECU is damaged).

 

this!!! To add to that, would be a good practice to voltage drop check the wiring at the sensor. The power and the signal by back probing the terminals. This would also tell you if youre not getting full readings. A continuity test is not enough in this case. As you could have one strand of wire connecting and pass that test. But not enough wires to carry the full amperage giving the full voltage reading

Also try to source down another s300. Load your map onto it. This will rule out the hondata circuitry

 

How can I test for a bad IAT circuit?

 

 

I have never performed a drop voltage test, but looking into it. Is there a video or resource you can recommend. I can do some basic electronic testing but feel like I'm in dark waters now.

 

No voltage test is necessary. If you confirm that the green/white (or green/black) wire is a ground, and then you check continuity between the IAT plug and the ECU plug of the red/yellow wire and it is good... then your wiring is OK.

 

On a broken wire, you can have can continuity through a wire end to end with only having one strand still connected. But not enough strands to carry full voltage

 

Limited stranding, in my experience, typically shows some (if not significant) resistance in the continuity test. If you are just using tone to detect continuity, you would be absolutely correct... you would still get tone even if only ONE strand is connected.

 

Here's a question, could I ground separately from the engine harness? Say if I do have continuity issues, could I just ground it in the bay?

 

Unfortunately not... it is a control ground. There are certainly other grounds that it could be tied into (the ECT sensor as an example) and it would work just fine. You cannot just ground it anywhere.